diff mbox

[v5,1/5] xen, gfx passthrough: basic graphics passthrough support

Message ID 1403662641-28526-2-git-send-email-tiejun.chen@intel.com
State New
Headers show

Commit Message

Tiejun Chen June 25, 2014, 2:17 a.m. UTC 
basic gfx passthrough support:
- add a vga type for gfx passthrough
- retrieve VGA bios from sysfs, then load it to guest at 0xC0000
- register/unregister legacy VGA I/O ports and MMIOs for passthrough GFX

The original patch is from Weidong Han <weidong.han@intel.com>

Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
Cc: Weidong Han <weidong.han@intel.com>
---
v5:

* Just rebase.

v4:

* Fix some typos in the patch head description.
* Improve some comments.
* Given that xen_pt_register_vga_regions()/xen_pt_unregister_vga_regions()
  are called unconditionally, so we just return 0 there.
* Remove one spurious change.

v3:

* Fix some typos.
* Add more comments to make that readable.
* Improve some return paths.

v2:

* retrieve VGA bios from sysfs properly.
* redefine some function name.

 hw/xen/Makefile.objs         |   2 +-
 hw/xen/xen-host-pci-device.c |   5 +
 hw/xen/xen-host-pci-device.h |   1 +
 hw/xen/xen_pt.c              |  10 ++
 hw/xen/xen_pt.h              |   4 +
 hw/xen/xen_pt_graphics.c     | 232 +++++++++++++++++++++++++++++++++++++++++++
 qemu-options.hx              |   9 ++
 vl.c                         |  10 ++
 8 files changed, 272 insertions(+), 1 deletion(-)
 create mode 100644 hw/xen/xen_pt_graphics.c

Comments

Paolo Bonzini June 25, 2014, 6:21 a.m. UTC | #1 
Il 25/06/2014 04:17, Tiejun Chen ha scritto:
> +static int get_vgabios(unsigned char *buf, XenHostPCIDevice *dev)
> +{
> +    char rom_file[64];
> +    FILE *fp;
> +    uint8_t val;
> +    struct stat st;
> +    uint16_t magic = 0;
> +    int ret = 0;
> +
> +    snprintf(rom_file, sizeof(rom_file),
> +             "/sys/bus/pci/devices/%04x:%02x:%02x.%d/rom",
> +             dev->domain, dev->bus, dev->dev,
> +             dev->func);
> +
> +    if (stat(rom_file, &st)) {
> +        return -ENODEV;
> +    }
> +
> +    if (access(rom_file, F_OK)) {
> +        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
> +                    rom_file);
> +        return -ENODEV;
> +    }

These two checks (stat and access) are useless.

> +    /* Write "1" to the ROM file to enable it */
> +    fp = fopen(rom_file, "r+");
> +    if (fp == NULL) {
> +        return -EACCES;
> +    }
> +    val = 1;
> +    if (fwrite(&val, 1, 1, fp) != 1) {
> +        XEN_PT_LOG("%s\n", "Failed to enable pci-sysfs rom file");
> +        ret = -EIO;
> +        goto close_rom;
> +    }
> +    fseek(fp, 0, SEEK_SET);
> +
> +    /*
> +     * Check if it a real bios extension.
> +     * The magic number is 0xAA55.
> +     */
> +    if (!fread(&magic, sizeof(magic), 1, fp)) {
> +        XEN_PT_ERR(NULL, "VGA: can't get magic.\n");
> +        ret = -ENODEV;
> +        goto close_rom;
> +    }
> +    if (magic != 0xAA55) {
> +        XEN_PT_ERR(NULL, "VGA: wrong magic %x.\n", magic);
> +        ret = -ENODEV;
> +        goto close_rom;
> +    }
> +    fseek(fp, 0, SEEK_SET);
> +
> +    if (!fread(buf, 1, st.st_size, fp)) {
> +        XEN_PT_ERR(NULL, "VGA: pci-assign: Cannot read from host %s", rom_file);
> +        XEN_PT_LOG(NULL, "VGA: Device option ROM contents are probably invalid "
> +                     "(check dmesg).\nSkip option ROM probe with rombar=0, "
> +                     "or load from file with romfile=\n");
> +    }
> +

Why is this graphics passthrough specific?  Should QEMU's Xen PCI 
passthrough read ROM BAR contents from network cards too, for example?

Paolo
Michael S. Tsirkin June 25, 2014, 6:35 a.m. UTC | #2 
On Wed, Jun 25, 2014 at 10:17:17AM +0800, Tiejun Chen wrote:
> basic gfx passthrough support:
> - add a vga type for gfx passthrough
> - retrieve VGA bios from sysfs, then load it to guest at 0xC0000
> - register/unregister legacy VGA I/O ports and MMIOs for passthrough GFX
> 
> The original patch is from Weidong Han <weidong.han@intel.com>
> 
> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> Cc: Weidong Han <weidong.han@intel.com>

ROM loading code is duplicated from assigned_dev_load_option_rom.
Would it be a problem for you to create a memory region holding
the ROM?
You won't need cpu_physical_memory_rw then, either, or need
the VGA_BIOS_DEFAULT_SIZE hack.




> ---
> v5:
> 
> * Just rebase.
> 
> v4:
> 
> * Fix some typos in the patch head description.
> * Improve some comments.
> * Given that xen_pt_register_vga_regions()/xen_pt_unregister_vga_regions()
>   are called unconditionally, so we just return 0 there.
> * Remove one spurious change.
> 
> v3:
> 
> * Fix some typos.
> * Add more comments to make that readable.
> * Improve some return paths.
> 
> v2:
> 
> * retrieve VGA bios from sysfs properly.
> * redefine some function name.
> 
>  hw/xen/Makefile.objs         |   2 +-
>  hw/xen/xen-host-pci-device.c |   5 +
>  hw/xen/xen-host-pci-device.h |   1 +
>  hw/xen/xen_pt.c              |  10 ++
>  hw/xen/xen_pt.h              |   4 +
>  hw/xen/xen_pt_graphics.c     | 232 +++++++++++++++++++++++++++++++++++++++++++
>  qemu-options.hx              |   9 ++
>  vl.c                         |  10 ++
>  8 files changed, 272 insertions(+), 1 deletion(-)
>  create mode 100644 hw/xen/xen_pt_graphics.c
> 
> diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
> index a0ca0aa..77b7dae 100644
> --- a/hw/xen/Makefile.objs
> +++ b/hw/xen/Makefile.objs
> @@ -2,4 +2,4 @@
>  common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
>  
>  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
> -obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o
> +obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o xen_pt_graphics.o
> diff --git a/hw/xen/xen-host-pci-device.c b/hw/xen/xen-host-pci-device.c
> index 743b37b..a54b7de 100644
> --- a/hw/xen/xen-host-pci-device.c
> +++ b/hw/xen/xen-host-pci-device.c
> @@ -376,6 +376,11 @@ int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
>          goto error;
>      }
>      d->irq = v;
> +    rc = xen_host_pci_get_hex_value(d, "class", &v);
> +    if (rc) {
> +        goto error;
> +    }
> +    d->class_code = v;
>      d->is_virtfn = xen_host_pci_dev_is_virtfn(d);
>  
>      return 0;
> diff --git a/hw/xen/xen-host-pci-device.h b/hw/xen/xen-host-pci-device.h
> index c2486f0..f1e1c30 100644
> --- a/hw/xen/xen-host-pci-device.h
> +++ b/hw/xen/xen-host-pci-device.h
> @@ -25,6 +25,7 @@ typedef struct XenHostPCIDevice {
>  
>      uint16_t vendor_id;
>      uint16_t device_id;
> +    uint32_t class_code;
>      int irq;
>  
>      XenHostPCIIORegion io_regions[PCI_NUM_REGIONS - 1];
> diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
> index be4220b..dac4238 100644
> --- a/hw/xen/xen_pt.c
> +++ b/hw/xen/xen_pt.c
> @@ -450,6 +450,7 @@ static int xen_pt_register_regions(XenPCIPassthroughState *s)
>                     d->rom.size, d->rom.base_addr);
>      }
>  
> +    xen_pt_register_vga_regions(d);
>      return 0;
>  }
>  
> @@ -470,6 +471,8 @@ static void xen_pt_unregister_regions(XenPCIPassthroughState *s)
>      if (d->rom.base_addr && d->rom.size) {
>          memory_region_destroy(&s->rom);
>      }
> +
> +    xen_pt_unregister_vga_regions(d);
>  }
>  
>  /* region mapping */
> @@ -693,6 +696,13 @@ static int xen_pt_initfn(PCIDevice *d)
>      /* Handle real device's MMIO/PIO BARs */
>      xen_pt_register_regions(s);
>  
> +    /* Setup VGA bios for passthrough GFX */
> +    if (xen_pt_setup_vga(&s->real_device) < 0) {
> +        XEN_PT_ERR(d, "Setup VGA BIOS of passthrough GFX failed!\n");
> +        xen_host_pci_device_put(&s->real_device);
> +        return -1;
> +    }
> +
>      /* reinitialize each config register to be emulated */
>      if (xen_pt_config_init(s)) {
>          XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");
> diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
> index 942dc60..4d3a18d 100644
> --- a/hw/xen/xen_pt.h
> +++ b/hw/xen/xen_pt.h
> @@ -298,5 +298,9 @@ static inline bool xen_pt_has_msix_mapping(XenPCIPassthroughState *s, int bar)
>      return s->msix && s->msix->bar_index == bar;
>  }
>  
> +extern int xen_has_gfx_passthru;
> +int xen_pt_register_vga_regions(XenHostPCIDevice *dev);
> +int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev);
> +int xen_pt_setup_vga(XenHostPCIDevice *dev);
>  
>  #endif /* !XEN_PT_H */
> diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
> new file mode 100644
> index 0000000..461e526
> --- /dev/null
> +++ b/hw/xen/xen_pt_graphics.c
> @@ -0,0 +1,232 @@
> +/*
> + * graphics passthrough
> + */
> +#include "xen_pt.h"
> +#include "xen-host-pci-device.h"
> +#include "hw/xen/xen_backend.h"
> +
> +static int is_vga_passthrough(XenHostPCIDevice *dev)
> +{
> +    return (xen_has_gfx_passthru
> +            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
> +}
> +
> +typedef struct VGARegion {
> +    int type;           /* Memory or port I/O */
> +    uint64_t guest_base_addr;
> +    uint64_t machine_base_addr;
> +    uint64_t size;    /* size of the region */
> +    int rc;
> +} VGARegion;
> +
> +#define IORESOURCE_IO           0x00000100
> +#define IORESOURCE_MEM          0x00000200
> +
> +static struct VGARegion vga_args[] = {
> +    {
> +        .type = IORESOURCE_IO,
> +        .guest_base_addr = 0x3B0,
> +        .machine_base_addr = 0x3B0,
> +        .size = 0xC,
> +        .rc = -1,
> +    },
> +    {
> +        .type = IORESOURCE_IO,
> +        .guest_base_addr = 0x3C0,
> +        .machine_base_addr = 0x3C0,
> +        .size = 0x20,
> +        .rc = -1,
> +    },
> +    {
> +        .type = IORESOURCE_MEM,
> +        .guest_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
> +        .machine_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
> +        .size = 0x20,
> +        .rc = -1,
> +    },
> +};
> +
> +/*
> + * register VGA resources for the domain with assigned gfx
> + */
> +int xen_pt_register_vga_regions(XenHostPCIDevice *dev)
> +{
> +    int i = 0;
> +
> +    if (!is_vga_passthrough(dev)) {
> +        return 0;
> +    }
> +
> +    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
> +        if (vga_args[i].type == IORESOURCE_IO) {
> +            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
> +                            vga_args[i].guest_base_addr,
> +                            vga_args[i].machine_base_addr,
> +                            vga_args[i].size, DPCI_ADD_MAPPING);
> +        } else {
> +            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
> +                            vga_args[i].guest_base_addr,
> +                            vga_args[i].machine_base_addr,
> +                            vga_args[i].size, DPCI_ADD_MAPPING);
> +        }
> +
> +        if (vga_args[i].rc) {
> +            XEN_PT_ERR(NULL, "VGA %s mapping failed! (rc: %i)\n",
> +                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
> +                    vga_args[i].rc);
> +            return vga_args[i].rc;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +/*
> + * unregister VGA resources for the domain with assigned gfx
> + */
> +int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
> +{
> +    int i = 0;
> +
> +    if (!is_vga_passthrough(dev)) {
> +        return 0;
> +    }
> +
> +    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
> +        if (vga_args[i].type == IORESOURCE_IO) {
> +            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
> +                            vga_args[i].guest_base_addr,
> +                            vga_args[i].machine_base_addr,
> +                            vga_args[i].size, DPCI_REMOVE_MAPPING);
> +        } else {
> +            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
> +                            vga_args[i].guest_base_addr,
> +                            vga_args[i].machine_base_addr,
> +                            vga_args[i].size, DPCI_REMOVE_MAPPING);
> +        }
> +
> +        if (vga_args[i].rc) {
> +            XEN_PT_ERR(NULL, "VGA %s unmapping failed! (rc: %i)\n",
> +                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
> +                    vga_args[i].rc);
> +            return vga_args[i].rc;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +static int get_vgabios(unsigned char *buf, XenHostPCIDevice *dev)
> +{
> +    char rom_file[64];
> +    FILE *fp;
> +    uint8_t val;
> +    struct stat st;
> +    uint16_t magic = 0;
> +    int ret = 0;
> +
> +    snprintf(rom_file, sizeof(rom_file),
> +             "/sys/bus/pci/devices/%04x:%02x:%02x.%d/rom",
> +             dev->domain, dev->bus, dev->dev,
> +             dev->func);
> +
> +    if (stat(rom_file, &st)) {
> +        return -ENODEV;
> +    }
> +
> +    if (access(rom_file, F_OK)) {
> +        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
> +                    rom_file);
> +        return -ENODEV;
> +    }
> +
> +    /* Write "1" to the ROM file to enable it */
> +    fp = fopen(rom_file, "r+");
> +    if (fp == NULL) {
> +        return -EACCES;
> +    }
> +    val = 1;
> +    if (fwrite(&val, 1, 1, fp) != 1) {
> +        XEN_PT_LOG("%s\n", "Failed to enable pci-sysfs rom file");
> +        ret = -EIO;
> +        goto close_rom;
> +    }
> +    fseek(fp, 0, SEEK_SET);
> +
> +    /*
> +     * Check if it a real bios extension.
> +     * The magic number is 0xAA55.
> +     */
> +    if (!fread(&magic, sizeof(magic), 1, fp)) {
> +        XEN_PT_ERR(NULL, "VGA: can't get magic.\n");
> +        ret = -ENODEV;
> +        goto close_rom;
> +    }
> +    if (magic != 0xAA55) {
> +        XEN_PT_ERR(NULL, "VGA: wrong magic %x.\n", magic);
> +        ret = -ENODEV;
> +        goto close_rom;
> +    }
> +    fseek(fp, 0, SEEK_SET);
> +
> +    if (!fread(buf, 1, st.st_size, fp)) {
> +        XEN_PT_ERR(NULL, "VGA: pci-assign: Cannot read from host %s", rom_file);
> +        XEN_PT_LOG(NULL, "VGA: Device option ROM contents are probably invalid "
> +                     "(check dmesg).\nSkip option ROM probe with rombar=0, "
> +                     "or load from file with romfile=\n");
> +    }
> +
> +close_rom:
> +    /* Write "0" to disable ROM */
> +    fseek(fp, 0, SEEK_SET);
> +    val = 0;
> +    if (!fwrite(&val, 1, 1, fp)) {
> +        ret = -EIO;
> +        XEN_PT_LOG("%s\n", "Failed to disable pci-sysfs rom file");
> +    }
> +    fclose(fp);
> +    return ret;
> +}
> +
> +/* Allocated 128K for the vga bios */
> +#define VGA_BIOS_DEFAULT_SIZE (0x20000)
> +
> +int xen_pt_setup_vga(XenHostPCIDevice *dev)
> +{
> +    unsigned char *bios = NULL;
> +    int bios_size = 0;
> +    char *c = NULL;
> +    char checksum = 0;
> +    int rc = 0;
> +
> +    if (!is_vga_passthrough(dev)) {
> +        return rc;
> +    }
> +
> +    bios = g_malloc0(VGA_BIOS_DEFAULT_SIZE);
> +
> +    bios_size = get_vgabios(bios, dev);
> +    if (bios_size) {
> +        XEN_PT_ERR(NULL, "VGA: Error %d getting VBIOS!\n", bios_size);
> +        if (bios_size < 0) {
> +            XEN_PT_ERR(NULL, "VGA: Error (%s).\n", strerror(bios_size));
> +        }
> +        rc = -1;
> +        goto out;
> +    }
> +
> +    /* Adjust the bios checksum */

It's easy to see that you do this here, but *why* do you do it?
That's what the comment should explain.
Do you see many ROMs with an invalid checksum
in the field?

> +    for (c = (char *)bios; c < ((char *)bios + bios_size); c++) {
> +        checksum += *c;
> +    }
> +    if (checksum) {
> +        bios[bios_size - 1] -= checksum;
> +        XEN_PT_LOG(NULL, "vga bios checksum is adjusted!\n");
> +    }
> +
> +    /* Currently we fixed this address as a primary. */
> +    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
> +out:
> +    g_free(bios);
> +    return rc;
> +}
> diff --git a/qemu-options.hx b/qemu-options.hx
> index ff76ad4..1c77baa 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -1066,6 +1066,15 @@ STEXI
>  Rotate graphical output some deg left (only PXA LCD).
>  ETEXI
>  
> +DEF("gfx_passthru", 0, QEMU_OPTION_gfx_passthru,
> +    "-gfx_passthru   enable Intel IGD passthrough by XEN\n",
> +    QEMU_ARCH_ALL)
> +STEXI
> +@item -gfx_passthru
> +@findex -gfx_passthru
> +Enable Intel IGD passthrough by XEN
> +ETEXI
> +
>  DEF("vga", HAS_ARG, QEMU_OPTION_vga,
>      "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|none]\n"
>      "                select video card type\n", QEMU_ARCH_ALL)
> diff --git a/vl.c b/vl.c
> index a1686ef..c5b572d 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1418,6 +1418,13 @@ static void configure_msg(QemuOpts *opts)
>      enable_timestamp_msg = qemu_opt_get_bool(opts, "timestamp", true);
>  }
>  
> +/* We still need this for compatibility with XEN. */
> +int xen_has_gfx_passthru;
> +static void xen_gfx_passthru(const char *optarg)
> +{
> +    xen_has_gfx_passthru = 1;
> +}
> +
>  /***********************************************************/
>  /* USB devices */
>  
> @@ -3945,6 +3952,9 @@ int main(int argc, char **argv, char **envp)
>                      exit(1);
>                  }
>                  break;
> +            case QEMU_OPTION_gfx_passthru:
> +                xen_gfx_passthru(optarg);
> +                break;
>              default:
>                  os_parse_cmd_args(popt->index, optarg);
>              }
> -- 
> 1.9.1
Tiejun Chen June 25, 2014, 7:48 a.m. UTC | #3 
On 2014/6/25 14:21, Paolo Bonzini wrote:
> Il 25/06/2014 04:17, Tiejun Chen ha scritto:
>> +static int get_vgabios(unsigned char *buf, XenHostPCIDevice *dev)
>> +{
>> +    char rom_file[64];
>> +    FILE *fp;
>> +    uint8_t val;
>> +    struct stat st;
>> +    uint16_t magic = 0;
>> +    int ret = 0;
>> +
>> +    snprintf(rom_file, sizeof(rom_file),
>> +             "/sys/bus/pci/devices/%04x:%02x:%02x.%d/rom",
>> +             dev->domain, dev->bus, dev->dev,
>> +             dev->func);
>> +
>> +    if (stat(rom_file, &st)) {
>> +        return -ENODEV;
>> +    }
>> +
>> +    if (access(rom_file, F_OK)) {
>> +        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
>> +                    rom_file);
>> +        return -ENODEV;
>> +    }
>
> These two checks (stat and access) are useless.

Will remove this.

>
>> +    /* Write "1" to the ROM file to enable it */
>> +    fp = fopen(rom_file, "r+");
>> +    if (fp == NULL) {
>> +        return -EACCES;
>> +    }
>> +    val = 1;
>> +    if (fwrite(&val, 1, 1, fp) != 1) {
>> +        XEN_PT_LOG("%s\n", "Failed to enable pci-sysfs rom file");
>> +        ret = -EIO;
>> +        goto close_rom;
>> +    }
>> +    fseek(fp, 0, SEEK_SET);
>> +
>> +    /*
>> +     * Check if it a real bios extension.
>> +     * The magic number is 0xAA55.
>> +     */
>> +    if (!fread(&magic, sizeof(magic), 1, fp)) {
>> +        XEN_PT_ERR(NULL, "VGA: can't get magic.\n");
>> +        ret = -ENODEV;
>> +        goto close_rom;
>> +    }
>> +    if (magic != 0xAA55) {
>> +        XEN_PT_ERR(NULL, "VGA: wrong magic %x.\n", magic);
>> +        ret = -ENODEV;
>> +        goto close_rom;
>> +    }
>> +    fseek(fp, 0, SEEK_SET);
>> +
>> +    if (!fread(buf, 1, st.st_size, fp)) {
>> +        XEN_PT_ERR(NULL, "VGA: pci-assign: Cannot read from host %s",
>> rom_file);
>> +        XEN_PT_LOG(NULL, "VGA: Device option ROM contents are
>> probably invalid "
>> +                     "(check dmesg).\nSkip option ROM probe with
>> rombar=0, "
>> +                     "or load from file with romfile=\n");
>> +    }
>> +
>
> Why is this graphics passthrough specific?  Should QEMU's Xen PCI
> passthrough read ROM BAR contents from network cards too, for example?
>

I think this should not be same simply since we need to call VBIOS from 
RAM, not a ROM BAR of the device.

Thanks
Tiejun
Tiejun Chen June 25, 2014, 9:06 a.m. UTC | #4 
On 2014/6/25 14:35, Michael S. Tsirkin wrote:
> On Wed, Jun 25, 2014 at 10:17:17AM +0800, Tiejun Chen wrote:
>> basic gfx passthrough support:
>> - add a vga type for gfx passthrough
>> - retrieve VGA bios from sysfs, then load it to guest at 0xC0000
>> - register/unregister legacy VGA I/O ports and MMIOs for passthrough GFX
>>
>> The original patch is from Weidong Han <weidong.han@intel.com>
>>
>> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
>> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
>> Cc: Weidong Han <weidong.han@intel.com>
>
> ROM loading code is duplicated from assigned_dev_load_option_rom.

Yes. Do you hint we need to split this?

> Would it be a problem for you to create a memory region holding
> the ROM?

Sorry, could you tell me what should do exactly?

> You won't need cpu_physical_memory_rw then, either, or need

How to make sure this is fixed at 0xc0000?

Thanks
Tiejun

> the VGA_BIOS_DEFAULT_SIZE hack.
>
>
>
>
>> ---
>> v5:
>>
>> * Just rebase.
>>
>> v4:
>>
>> * Fix some typos in the patch head description.
>> * Improve some comments.
>> * Given that xen_pt_register_vga_regions()/xen_pt_unregister_vga_regions()
>>    are called unconditionally, so we just return 0 there.
>> * Remove one spurious change.
>>
>> v3:
>>
>> * Fix some typos.
>> * Add more comments to make that readable.
>> * Improve some return paths.
>>
>> v2:
>>
>> * retrieve VGA bios from sysfs properly.
>> * redefine some function name.
>>
>>   hw/xen/Makefile.objs         |   2 +-
>>   hw/xen/xen-host-pci-device.c |   5 +
>>   hw/xen/xen-host-pci-device.h |   1 +
>>   hw/xen/xen_pt.c              |  10 ++
>>   hw/xen/xen_pt.h              |   4 +
>>   hw/xen/xen_pt_graphics.c     | 232 +++++++++++++++++++++++++++++++++++++++++++
>>   qemu-options.hx              |   9 ++
>>   vl.c                         |  10 ++
>>   8 files changed, 272 insertions(+), 1 deletion(-)
>>   create mode 100644 hw/xen/xen_pt_graphics.c
>>
>> diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
>> index a0ca0aa..77b7dae 100644
>> --- a/hw/xen/Makefile.objs
>> +++ b/hw/xen/Makefile.objs
>> @@ -2,4 +2,4 @@
>>   common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
>>
>>   obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
>> -obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o
>> +obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o xen_pt_graphics.o
>> diff --git a/hw/xen/xen-host-pci-device.c b/hw/xen/xen-host-pci-device.c
>> index 743b37b..a54b7de 100644
>> --- a/hw/xen/xen-host-pci-device.c
>> +++ b/hw/xen/xen-host-pci-device.c
>> @@ -376,6 +376,11 @@ int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
>>           goto error;
>>       }
>>       d->irq = v;
>> +    rc = xen_host_pci_get_hex_value(d, "class", &v);
>> +    if (rc) {
>> +        goto error;
>> +    }
>> +    d->class_code = v;
>>       d->is_virtfn = xen_host_pci_dev_is_virtfn(d);
>>
>>       return 0;
>> diff --git a/hw/xen/xen-host-pci-device.h b/hw/xen/xen-host-pci-device.h
>> index c2486f0..f1e1c30 100644
>> --- a/hw/xen/xen-host-pci-device.h
>> +++ b/hw/xen/xen-host-pci-device.h
>> @@ -25,6 +25,7 @@ typedef struct XenHostPCIDevice {
>>
>>       uint16_t vendor_id;
>>       uint16_t device_id;
>> +    uint32_t class_code;
>>       int irq;
>>
>>       XenHostPCIIORegion io_regions[PCI_NUM_REGIONS - 1];
>> diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
>> index be4220b..dac4238 100644
>> --- a/hw/xen/xen_pt.c
>> +++ b/hw/xen/xen_pt.c
>> @@ -450,6 +450,7 @@ static int xen_pt_register_regions(XenPCIPassthroughState *s)
>>                      d->rom.size, d->rom.base_addr);
>>       }
>>
>> +    xen_pt_register_vga_regions(d);
>>       return 0;
>>   }
>>
>> @@ -470,6 +471,8 @@ static void xen_pt_unregister_regions(XenPCIPassthroughState *s)
>>       if (d->rom.base_addr && d->rom.size) {
>>           memory_region_destroy(&s->rom);
>>       }
>> +
>> +    xen_pt_unregister_vga_regions(d);
>>   }
>>
>>   /* region mapping */
>> @@ -693,6 +696,13 @@ static int xen_pt_initfn(PCIDevice *d)
>>       /* Handle real device's MMIO/PIO BARs */
>>       xen_pt_register_regions(s);
>>
>> +    /* Setup VGA bios for passthrough GFX */
>> +    if (xen_pt_setup_vga(&s->real_device) < 0) {
>> +        XEN_PT_ERR(d, "Setup VGA BIOS of passthrough GFX failed!\n");
>> +        xen_host_pci_device_put(&s->real_device);
>> +        return -1;
>> +    }
>> +
>>       /* reinitialize each config register to be emulated */
>>       if (xen_pt_config_init(s)) {
>>           XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");
>> diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
>> index 942dc60..4d3a18d 100644
>> --- a/hw/xen/xen_pt.h
>> +++ b/hw/xen/xen_pt.h
>> @@ -298,5 +298,9 @@ static inline bool xen_pt_has_msix_mapping(XenPCIPassthroughState *s, int bar)
>>       return s->msix && s->msix->bar_index == bar;
>>   }
>>
>> +extern int xen_has_gfx_passthru;
>> +int xen_pt_register_vga_regions(XenHostPCIDevice *dev);
>> +int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev);
>> +int xen_pt_setup_vga(XenHostPCIDevice *dev);
>>
>>   #endif /* !XEN_PT_H */
>> diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
>> new file mode 100644
>> index 0000000..461e526
>> --- /dev/null
>> +++ b/hw/xen/xen_pt_graphics.c
>> @@ -0,0 +1,232 @@
>> +/*
>> + * graphics passthrough
>> + */
>> +#include "xen_pt.h"
>> +#include "xen-host-pci-device.h"
>> +#include "hw/xen/xen_backend.h"
>> +
>> +static int is_vga_passthrough(XenHostPCIDevice *dev)
>> +{
>> +    return (xen_has_gfx_passthru
>> +            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
>> +}
>> +
>> +typedef struct VGARegion {
>> +    int type;           /* Memory or port I/O */
>> +    uint64_t guest_base_addr;
>> +    uint64_t machine_base_addr;
>> +    uint64_t size;    /* size of the region */
>> +    int rc;
>> +} VGARegion;
>> +
>> +#define IORESOURCE_IO           0x00000100
>> +#define IORESOURCE_MEM          0x00000200
>> +
>> +static struct VGARegion vga_args[] = {
>> +    {
>> +        .type = IORESOURCE_IO,
>> +        .guest_base_addr = 0x3B0,
>> +        .machine_base_addr = 0x3B0,
>> +        .size = 0xC,
>> +        .rc = -1,
>> +    },
>> +    {
>> +        .type = IORESOURCE_IO,
>> +        .guest_base_addr = 0x3C0,
>> +        .machine_base_addr = 0x3C0,
>> +        .size = 0x20,
>> +        .rc = -1,
>> +    },
>> +    {
>> +        .type = IORESOURCE_MEM,
>> +        .guest_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
>> +        .machine_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
>> +        .size = 0x20,
>> +        .rc = -1,
>> +    },
>> +};
>> +
>> +/*
>> + * register VGA resources for the domain with assigned gfx
>> + */
>> +int xen_pt_register_vga_regions(XenHostPCIDevice *dev)
>> +{
>> +    int i = 0;
>> +
>> +    if (!is_vga_passthrough(dev)) {
>> +        return 0;
>> +    }
>> +
>> +    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
>> +        if (vga_args[i].type == IORESOURCE_IO) {
>> +            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_ADD_MAPPING);
>> +        } else {
>> +            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_ADD_MAPPING);
>> +        }
>> +
>> +        if (vga_args[i].rc) {
>> +            XEN_PT_ERR(NULL, "VGA %s mapping failed! (rc: %i)\n",
>> +                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
>> +                    vga_args[i].rc);
>> +            return vga_args[i].rc;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +/*
>> + * unregister VGA resources for the domain with assigned gfx
>> + */
>> +int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
>> +{
>> +    int i = 0;
>> +
>> +    if (!is_vga_passthrough(dev)) {
>> +        return 0;
>> +    }
>> +
>> +    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
>> +        if (vga_args[i].type == IORESOURCE_IO) {
>> +            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_REMOVE_MAPPING);
>> +        } else {
>> +            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_REMOVE_MAPPING);
>> +        }
>> +
>> +        if (vga_args[i].rc) {
>> +            XEN_PT_ERR(NULL, "VGA %s unmapping failed! (rc: %i)\n",
>> +                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
>> +                    vga_args[i].rc);
>> +            return vga_args[i].rc;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int get_vgabios(unsigned char *buf, XenHostPCIDevice *dev)
>> +{
>> +    char rom_file[64];
>> +    FILE *fp;
>> +    uint8_t val;
>> +    struct stat st;
>> +    uint16_t magic = 0;
>> +    int ret = 0;
>> +
>> +    snprintf(rom_file, sizeof(rom_file),
>> +             "/sys/bus/pci/devices/%04x:%02x:%02x.%d/rom",
>> +             dev->domain, dev->bus, dev->dev,
>> +             dev->func);
>> +
>> +    if (stat(rom_file, &st)) {
>> +        return -ENODEV;
>> +    }
>> +
>> +    if (access(rom_file, F_OK)) {
>> +        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
>> +                    rom_file);
>> +        return -ENODEV;
>> +    }
>> +
>> +    /* Write "1" to the ROM file to enable it */
>> +    fp = fopen(rom_file, "r+");
>> +    if (fp == NULL) {
>> +        return -EACCES;
>> +    }
>> +    val = 1;
>> +    if (fwrite(&val, 1, 1, fp) != 1) {
>> +        XEN_PT_LOG("%s\n", "Failed to enable pci-sysfs rom file");
>> +        ret = -EIO;
>> +        goto close_rom;
>> +    }
>> +    fseek(fp, 0, SEEK_SET);
>> +
>> +    /*
>> +     * Check if it a real bios extension.
>> +     * The magic number is 0xAA55.
>> +     */
>> +    if (!fread(&magic, sizeof(magic), 1, fp)) {
>> +        XEN_PT_ERR(NULL, "VGA: can't get magic.\n");
>> +        ret = -ENODEV;
>> +        goto close_rom;
>> +    }
>> +    if (magic != 0xAA55) {
>> +        XEN_PT_ERR(NULL, "VGA: wrong magic %x.\n", magic);
>> +        ret = -ENODEV;
>> +        goto close_rom;
>> +    }
>> +    fseek(fp, 0, SEEK_SET);
>> +
>> +    if (!fread(buf, 1, st.st_size, fp)) {
>> +        XEN_PT_ERR(NULL, "VGA: pci-assign: Cannot read from host %s", rom_file);
>> +        XEN_PT_LOG(NULL, "VGA: Device option ROM contents are probably invalid "
>> +                     "(check dmesg).\nSkip option ROM probe with rombar=0, "
>> +                     "or load from file with romfile=\n");
>> +    }
>> +
>> +close_rom:
>> +    /* Write "0" to disable ROM */
>> +    fseek(fp, 0, SEEK_SET);
>> +    val = 0;
>> +    if (!fwrite(&val, 1, 1, fp)) {
>> +        ret = -EIO;
>> +        XEN_PT_LOG("%s\n", "Failed to disable pci-sysfs rom file");
>> +    }
>> +    fclose(fp);
>> +    return ret;
>> +}
>> +
>> +/* Allocated 128K for the vga bios */
>> +#define VGA_BIOS_DEFAULT_SIZE (0x20000)
>> +
>> +int xen_pt_setup_vga(XenHostPCIDevice *dev)
>> +{
>> +    unsigned char *bios = NULL;
>> +    int bios_size = 0;
>> +    char *c = NULL;
>> +    char checksum = 0;
>> +    int rc = 0;
>> +
>> +    if (!is_vga_passthrough(dev)) {
>> +        return rc;
>> +    }
>> +
>> +    bios = g_malloc0(VGA_BIOS_DEFAULT_SIZE);
>> +
>> +    bios_size = get_vgabios(bios, dev);
>> +    if (bios_size) {
>> +        XEN_PT_ERR(NULL, "VGA: Error %d getting VBIOS!\n", bios_size);
>> +        if (bios_size < 0) {
>> +            XEN_PT_ERR(NULL, "VGA: Error (%s).\n", strerror(bios_size));
>> +        }
>> +        rc = -1;
>> +        goto out;
>> +    }
>> +
>> +    /* Adjust the bios checksum */
>
> It's easy to see that you do this here, but *why* do you do it?
> That's what the comment should explain.
> Do you see many ROMs with an invalid checksum
> in the field?
>
>> +    for (c = (char *)bios; c < ((char *)bios + bios_size); c++) {
>> +        checksum += *c;
>> +    }
>> +    if (checksum) {
>> +        bios[bios_size - 1] -= checksum;
>> +        XEN_PT_LOG(NULL, "vga bios checksum is adjusted!\n");
>> +    }
>> +
>> +    /* Currently we fixed this address as a primary. */
>> +    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
>> +out:
>> +    g_free(bios);
>> +    return rc;
>> +}
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index ff76ad4..1c77baa 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -1066,6 +1066,15 @@ STEXI
>>   Rotate graphical output some deg left (only PXA LCD).
>>   ETEXI
>>
>> +DEF("gfx_passthru", 0, QEMU_OPTION_gfx_passthru,
>> +    "-gfx_passthru   enable Intel IGD passthrough by XEN\n",
>> +    QEMU_ARCH_ALL)
>> +STEXI
>> +@item -gfx_passthru
>> +@findex -gfx_passthru
>> +Enable Intel IGD passthrough by XEN
>> +ETEXI
>> +
>>   DEF("vga", HAS_ARG, QEMU_OPTION_vga,
>>       "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|none]\n"
>>       "                select video card type\n", QEMU_ARCH_ALL)
>> diff --git a/vl.c b/vl.c
>> index a1686ef..c5b572d 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -1418,6 +1418,13 @@ static void configure_msg(QemuOpts *opts)
>>       enable_timestamp_msg = qemu_opt_get_bool(opts, "timestamp", true);
>>   }
>>
>> +/* We still need this for compatibility with XEN. */
>> +int xen_has_gfx_passthru;
>> +static void xen_gfx_passthru(const char *optarg)
>> +{
>> +    xen_has_gfx_passthru = 1;
>> +}
>> +
>>   /***********************************************************/
>>   /* USB devices */
>>
>> @@ -3945,6 +3952,9 @@ int main(int argc, char **argv, char **envp)
>>                       exit(1);
>>                   }
>>                   break;
>> +            case QEMU_OPTION_gfx_passthru:
>> +                xen_gfx_passthru(optarg);
>> +                break;
>>               default:
>>                   os_parse_cmd_args(popt->index, optarg);
>>               }
>> --
>> 1.9.1
>
>
Michael S. Tsirkin June 25, 2014, 9:16 a.m. UTC | #5 
On Wed, Jun 25, 2014 at 05:06:37PM +0800, Chen, Tiejun wrote:
> On 2014/6/25 14:35, Michael S. Tsirkin wrote:
> >On Wed, Jun 25, 2014 at 10:17:17AM +0800, Tiejun Chen wrote:
> >>basic gfx passthrough support:
> >>- add a vga type for gfx passthrough
> >>- retrieve VGA bios from sysfs, then load it to guest at 0xC0000
> >>- register/unregister legacy VGA I/O ports and MMIOs for passthrough GFX
> >>
> >>The original patch is from Weidong Han <weidong.han@intel.com>
> >>
> >>Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> >>Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> >>Cc: Weidong Han <weidong.han@intel.com>
> >
> >ROM loading code is duplicated from assigned_dev_load_option_rom.
> 
> Yes. Do you hint we need to split this?

Absolutely. These two drivers need to start sharing code.

> >Would it be a problem for you to create a memory region holding
> >the ROM?
> 
> Sorry, could you tell me what should do exactly?

Split common code out and reuse :)

> >You won't need cpu_physical_memory_rw then, either, or need
> 
> How to make sure this is fixed at 0xc0000?
> 
> Thanks
> Tiejun

I guess you just add it as subregion of system memory at this offset,
maybe with a higher priority than RAM.
Right, Paolo?

> >the VGA_BIOS_DEFAULT_SIZE hack.
> >
> >
> >
> >
> >>---
> >>v5:
> >>
> >>* Just rebase.
> >>
> >>v4:
> >>
> >>* Fix some typos in the patch head description.
> >>* Improve some comments.
> >>* Given that xen_pt_register_vga_regions()/xen_pt_unregister_vga_regions()
> >>   are called unconditionally, so we just return 0 there.
> >>* Remove one spurious change.
> >>
> >>v3:
> >>
> >>* Fix some typos.
> >>* Add more comments to make that readable.
> >>* Improve some return paths.
> >>
> >>v2:
> >>
> >>* retrieve VGA bios from sysfs properly.
> >>* redefine some function name.
> >>
> >>  hw/xen/Makefile.objs         |   2 +-
> >>  hw/xen/xen-host-pci-device.c |   5 +
> >>  hw/xen/xen-host-pci-device.h |   1 +
> >>  hw/xen/xen_pt.c              |  10 ++
> >>  hw/xen/xen_pt.h              |   4 +
> >>  hw/xen/xen_pt_graphics.c     | 232 +++++++++++++++++++++++++++++++++++++++++++
> >>  qemu-options.hx              |   9 ++
> >>  vl.c                         |  10 ++
> >>  8 files changed, 272 insertions(+), 1 deletion(-)
> >>  create mode 100644 hw/xen/xen_pt_graphics.c
> >>
> >>diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
> >>index a0ca0aa..77b7dae 100644
> >>--- a/hw/xen/Makefile.objs
> >>+++ b/hw/xen/Makefile.objs
> >>@@ -2,4 +2,4 @@
> >>  common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
> >>
> >>  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
> >>-obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o
> >>+obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o xen_pt_graphics.o
> >>diff --git a/hw/xen/xen-host-pci-device.c b/hw/xen/xen-host-pci-device.c
> >>index 743b37b..a54b7de 100644
> >>--- a/hw/xen/xen-host-pci-device.c
> >>+++ b/hw/xen/xen-host-pci-device.c
> >>@@ -376,6 +376,11 @@ int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
> >>          goto error;
> >>      }
> >>      d->irq = v;
> >>+    rc = xen_host_pci_get_hex_value(d, "class", &v);
> >>+    if (rc) {
> >>+        goto error;
> >>+    }
> >>+    d->class_code = v;
> >>      d->is_virtfn = xen_host_pci_dev_is_virtfn(d);
> >>
> >>      return 0;
> >>diff --git a/hw/xen/xen-host-pci-device.h b/hw/xen/xen-host-pci-device.h
> >>index c2486f0..f1e1c30 100644
> >>--- a/hw/xen/xen-host-pci-device.h
> >>+++ b/hw/xen/xen-host-pci-device.h
> >>@@ -25,6 +25,7 @@ typedef struct XenHostPCIDevice {
> >>
> >>      uint16_t vendor_id;
> >>      uint16_t device_id;
> >>+    uint32_t class_code;
> >>      int irq;
> >>
> >>      XenHostPCIIORegion io_regions[PCI_NUM_REGIONS - 1];
> >>diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
> >>index be4220b..dac4238 100644
> >>--- a/hw/xen/xen_pt.c
> >>+++ b/hw/xen/xen_pt.c
> >>@@ -450,6 +450,7 @@ static int xen_pt_register_regions(XenPCIPassthroughState *s)
> >>                     d->rom.size, d->rom.base_addr);
> >>      }
> >>
> >>+    xen_pt_register_vga_regions(d);
> >>      return 0;
> >>  }
> >>
> >>@@ -470,6 +471,8 @@ static void xen_pt_unregister_regions(XenPCIPassthroughState *s)
> >>      if (d->rom.base_addr && d->rom.size) {
> >>          memory_region_destroy(&s->rom);
> >>      }
> >>+
> >>+    xen_pt_unregister_vga_regions(d);
> >>  }
> >>
> >>  /* region mapping */
> >>@@ -693,6 +696,13 @@ static int xen_pt_initfn(PCIDevice *d)
> >>      /* Handle real device's MMIO/PIO BARs */
> >>      xen_pt_register_regions(s);
> >>
> >>+    /* Setup VGA bios for passthrough GFX */
> >>+    if (xen_pt_setup_vga(&s->real_device) < 0) {
> >>+        XEN_PT_ERR(d, "Setup VGA BIOS of passthrough GFX failed!\n");
> >>+        xen_host_pci_device_put(&s->real_device);
> >>+        return -1;
> >>+    }
> >>+
> >>      /* reinitialize each config register to be emulated */
> >>      if (xen_pt_config_init(s)) {
> >>          XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");
> >>diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
> >>index 942dc60..4d3a18d 100644
> >>--- a/hw/xen/xen_pt.h
> >>+++ b/hw/xen/xen_pt.h
> >>@@ -298,5 +298,9 @@ static inline bool xen_pt_has_msix_mapping(XenPCIPassthroughState *s, int bar)
> >>      return s->msix && s->msix->bar_index == bar;
> >>  }
> >>
> >>+extern int xen_has_gfx_passthru;
> >>+int xen_pt_register_vga_regions(XenHostPCIDevice *dev);
> >>+int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev);
> >>+int xen_pt_setup_vga(XenHostPCIDevice *dev);
> >>
> >>  #endif /* !XEN_PT_H */
> >>diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
> >>new file mode 100644
> >>index 0000000..461e526
> >>--- /dev/null
> >>+++ b/hw/xen/xen_pt_graphics.c
> >>@@ -0,0 +1,232 @@
> >>+/*
> >>+ * graphics passthrough
> >>+ */
> >>+#include "xen_pt.h"
> >>+#include "xen-host-pci-device.h"
> >>+#include "hw/xen/xen_backend.h"
> >>+
> >>+static int is_vga_passthrough(XenHostPCIDevice *dev)
> >>+{
> >>+    return (xen_has_gfx_passthru
> >>+            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
> >>+}
> >>+
> >>+typedef struct VGARegion {
> >>+    int type;           /* Memory or port I/O */
> >>+    uint64_t guest_base_addr;
> >>+    uint64_t machine_base_addr;
> >>+    uint64_t size;    /* size of the region */
> >>+    int rc;
> >>+} VGARegion;
> >>+
> >>+#define IORESOURCE_IO           0x00000100
> >>+#define IORESOURCE_MEM          0x00000200
> >>+
> >>+static struct VGARegion vga_args[] = {
> >>+    {
> >>+        .type = IORESOURCE_IO,
> >>+        .guest_base_addr = 0x3B0,
> >>+        .machine_base_addr = 0x3B0,
> >>+        .size = 0xC,
> >>+        .rc = -1,
> >>+    },
> >>+    {
> >>+        .type = IORESOURCE_IO,
> >>+        .guest_base_addr = 0x3C0,
> >>+        .machine_base_addr = 0x3C0,
> >>+        .size = 0x20,
> >>+        .rc = -1,
> >>+    },
> >>+    {
> >>+        .type = IORESOURCE_MEM,
> >>+        .guest_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
> >>+        .machine_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
> >>+        .size = 0x20,
> >>+        .rc = -1,
> >>+    },
> >>+};
> >>+
> >>+/*
> >>+ * register VGA resources for the domain with assigned gfx
> >>+ */
> >>+int xen_pt_register_vga_regions(XenHostPCIDevice *dev)
> >>+{
> >>+    int i = 0;
> >>+
> >>+    if (!is_vga_passthrough(dev)) {
> >>+        return 0;
> >>+    }
> >>+
> >>+    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
> >>+        if (vga_args[i].type == IORESOURCE_IO) {
> >>+            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
> >>+                            vga_args[i].guest_base_addr,
> >>+                            vga_args[i].machine_base_addr,
> >>+                            vga_args[i].size, DPCI_ADD_MAPPING);
> >>+        } else {
> >>+            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
> >>+                            vga_args[i].guest_base_addr,
> >>+                            vga_args[i].machine_base_addr,
> >>+                            vga_args[i].size, DPCI_ADD_MAPPING);
> >>+        }
> >>+
> >>+        if (vga_args[i].rc) {
> >>+            XEN_PT_ERR(NULL, "VGA %s mapping failed! (rc: %i)\n",
> >>+                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
> >>+                    vga_args[i].rc);
> >>+            return vga_args[i].rc;
> >>+        }
> >>+    }
> >>+
> >>+    return 0;
> >>+}
> >>+
> >>+/*
> >>+ * unregister VGA resources for the domain with assigned gfx
> >>+ */
> >>+int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
> >>+{
> >>+    int i = 0;
> >>+
> >>+    if (!is_vga_passthrough(dev)) {
> >>+        return 0;
> >>+    }
> >>+
> >>+    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
> >>+        if (vga_args[i].type == IORESOURCE_IO) {
> >>+            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
> >>+                            vga_args[i].guest_base_addr,
> >>+                            vga_args[i].machine_base_addr,
> >>+                            vga_args[i].size, DPCI_REMOVE_MAPPING);
> >>+        } else {
> >>+            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
> >>+                            vga_args[i].guest_base_addr,
> >>+                            vga_args[i].machine_base_addr,
> >>+                            vga_args[i].size, DPCI_REMOVE_MAPPING);
> >>+        }
> >>+
> >>+        if (vga_args[i].rc) {
> >>+            XEN_PT_ERR(NULL, "VGA %s unmapping failed! (rc: %i)\n",
> >>+                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
> >>+                    vga_args[i].rc);
> >>+            return vga_args[i].rc;
> >>+        }
> >>+    }
> >>+
> >>+    return 0;
> >>+}
> >>+
> >>+static int get_vgabios(unsigned char *buf, XenHostPCIDevice *dev)
> >>+{
> >>+    char rom_file[64];
> >>+    FILE *fp;
> >>+    uint8_t val;
> >>+    struct stat st;
> >>+    uint16_t magic = 0;
> >>+    int ret = 0;
> >>+
> >>+    snprintf(rom_file, sizeof(rom_file),
> >>+             "/sys/bus/pci/devices/%04x:%02x:%02x.%d/rom",
> >>+             dev->domain, dev->bus, dev->dev,
> >>+             dev->func);
> >>+
> >>+    if (stat(rom_file, &st)) {
> >>+        return -ENODEV;
> >>+    }
> >>+
> >>+    if (access(rom_file, F_OK)) {
> >>+        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
> >>+                    rom_file);
> >>+        return -ENODEV;
> >>+    }
> >>+
> >>+    /* Write "1" to the ROM file to enable it */
> >>+    fp = fopen(rom_file, "r+");
> >>+    if (fp == NULL) {
> >>+        return -EACCES;
> >>+    }
> >>+    val = 1;
> >>+    if (fwrite(&val, 1, 1, fp) != 1) {
> >>+        XEN_PT_LOG("%s\n", "Failed to enable pci-sysfs rom file");
> >>+        ret = -EIO;
> >>+        goto close_rom;
> >>+    }
> >>+    fseek(fp, 0, SEEK_SET);
> >>+
> >>+    /*
> >>+     * Check if it a real bios extension.
> >>+     * The magic number is 0xAA55.
> >>+     */
> >>+    if (!fread(&magic, sizeof(magic), 1, fp)) {
> >>+        XEN_PT_ERR(NULL, "VGA: can't get magic.\n");
> >>+        ret = -ENODEV;
> >>+        goto close_rom;
> >>+    }
> >>+    if (magic != 0xAA55) {
> >>+        XEN_PT_ERR(NULL, "VGA: wrong magic %x.\n", magic);
> >>+        ret = -ENODEV;
> >>+        goto close_rom;
> >>+    }
> >>+    fseek(fp, 0, SEEK_SET);
> >>+
> >>+    if (!fread(buf, 1, st.st_size, fp)) {
> >>+        XEN_PT_ERR(NULL, "VGA: pci-assign: Cannot read from host %s", rom_file);
> >>+        XEN_PT_LOG(NULL, "VGA: Device option ROM contents are probably invalid "
> >>+                     "(check dmesg).\nSkip option ROM probe with rombar=0, "
> >>+                     "or load from file with romfile=\n");
> >>+    }
> >>+
> >>+close_rom:
> >>+    /* Write "0" to disable ROM */
> >>+    fseek(fp, 0, SEEK_SET);
> >>+    val = 0;
> >>+    if (!fwrite(&val, 1, 1, fp)) {
> >>+        ret = -EIO;
> >>+        XEN_PT_LOG("%s\n", "Failed to disable pci-sysfs rom file");
> >>+    }
> >>+    fclose(fp);
> >>+    return ret;
> >>+}
> >>+
> >>+/* Allocated 128K for the vga bios */
> >>+#define VGA_BIOS_DEFAULT_SIZE (0x20000)
> >>+
> >>+int xen_pt_setup_vga(XenHostPCIDevice *dev)
> >>+{
> >>+    unsigned char *bios = NULL;
> >>+    int bios_size = 0;
> >>+    char *c = NULL;
> >>+    char checksum = 0;
> >>+    int rc = 0;
> >>+
> >>+    if (!is_vga_passthrough(dev)) {
> >>+        return rc;
> >>+    }
> >>+
> >>+    bios = g_malloc0(VGA_BIOS_DEFAULT_SIZE);
> >>+
> >>+    bios_size = get_vgabios(bios, dev);
> >>+    if (bios_size) {
> >>+        XEN_PT_ERR(NULL, "VGA: Error %d getting VBIOS!\n", bios_size);
> >>+        if (bios_size < 0) {
> >>+            XEN_PT_ERR(NULL, "VGA: Error (%s).\n", strerror(bios_size));
> >>+        }
> >>+        rc = -1;
> >>+        goto out;
> >>+    }
> >>+
> >>+    /* Adjust the bios checksum */
> >
> >It's easy to see that you do this here, but *why* do you do it?
> >That's what the comment should explain.
> >Do you see many ROMs with an invalid checksum
> >in the field?
> >
> >>+    for (c = (char *)bios; c < ((char *)bios + bios_size); c++) {
> >>+        checksum += *c;
> >>+    }
> >>+    if (checksum) {
> >>+        bios[bios_size - 1] -= checksum;
> >>+        XEN_PT_LOG(NULL, "vga bios checksum is adjusted!\n");
> >>+    }
> >>+
> >>+    /* Currently we fixed this address as a primary. */
> >>+    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
> >>+out:
> >>+    g_free(bios);
> >>+    return rc;
> >>+}
> >>diff --git a/qemu-options.hx b/qemu-options.hx
> >>index ff76ad4..1c77baa 100644
> >>--- a/qemu-options.hx
> >>+++ b/qemu-options.hx
> >>@@ -1066,6 +1066,15 @@ STEXI
> >>  Rotate graphical output some deg left (only PXA LCD).
> >>  ETEXI
> >>
> >>+DEF("gfx_passthru", 0, QEMU_OPTION_gfx_passthru,
> >>+    "-gfx_passthru   enable Intel IGD passthrough by XEN\n",
> >>+    QEMU_ARCH_ALL)
> >>+STEXI
> >>+@item -gfx_passthru
> >>+@findex -gfx_passthru
> >>+Enable Intel IGD passthrough by XEN
> >>+ETEXI
> >>+
> >>  DEF("vga", HAS_ARG, QEMU_OPTION_vga,
> >>      "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|none]\n"
> >>      "                select video card type\n", QEMU_ARCH_ALL)
> >>diff --git a/vl.c b/vl.c
> >>index a1686ef..c5b572d 100644
> >>--- a/vl.c
> >>+++ b/vl.c
> >>@@ -1418,6 +1418,13 @@ static void configure_msg(QemuOpts *opts)
> >>      enable_timestamp_msg = qemu_opt_get_bool(opts, "timestamp", true);
> >>  }
> >>
> >>+/* We still need this for compatibility with XEN. */
> >>+int xen_has_gfx_passthru;
> >>+static void xen_gfx_passthru(const char *optarg)
> >>+{
> >>+    xen_has_gfx_passthru = 1;
> >>+}
> >>+
> >>  /***********************************************************/
> >>  /* USB devices */
> >>
> >>@@ -3945,6 +3952,9 @@ int main(int argc, char **argv, char **envp)
> >>                      exit(1);
> >>                  }
> >>                  break;
> >>+            case QEMU_OPTION_gfx_passthru:
> >>+                xen_gfx_passthru(optarg);
> >>+                break;
> >>              default:
> >>                  os_parse_cmd_args(popt->index, optarg);
> >>              }
> >>--
> >>1.9.1
> >
> >
diff mbox

Patch

diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
index a0ca0aa..77b7dae 100644
--- a/hw/xen/Makefile.objs
+++ b/hw/xen/Makefile.objs
@@ -2,4 +2,4 @@ 
 common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
 
 obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
-obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o
+obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o xen_pt_graphics.o
diff --git a/hw/xen/xen-host-pci-device.c b/hw/xen/xen-host-pci-device.c
index 743b37b..a54b7de 100644
--- a/hw/xen/xen-host-pci-device.c
+++ b/hw/xen/xen-host-pci-device.c
@@ -376,6 +376,11 @@  int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
         goto error;
     }
     d->irq = v;
+    rc = xen_host_pci_get_hex_value(d, "class", &v);
+    if (rc) {
+        goto error;
+    }
+    d->class_code = v;
     d->is_virtfn = xen_host_pci_dev_is_virtfn(d);
 
     return 0;
diff --git a/hw/xen/xen-host-pci-device.h b/hw/xen/xen-host-pci-device.h
index c2486f0..f1e1c30 100644
--- a/hw/xen/xen-host-pci-device.h
+++ b/hw/xen/xen-host-pci-device.h
@@ -25,6 +25,7 @@  typedef struct XenHostPCIDevice {
 
     uint16_t vendor_id;
     uint16_t device_id;
+    uint32_t class_code;
     int irq;
 
     XenHostPCIIORegion io_regions[PCI_NUM_REGIONS - 1];
diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index be4220b..dac4238 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -450,6 +450,7 @@  static int xen_pt_register_regions(XenPCIPassthroughState *s)
                    d->rom.size, d->rom.base_addr);
     }
 
+    xen_pt_register_vga_regions(d);
     return 0;
 }
 
@@ -470,6 +471,8 @@  static void xen_pt_unregister_regions(XenPCIPassthroughState *s)
     if (d->rom.base_addr && d->rom.size) {
         memory_region_destroy(&s->rom);
     }
+
+    xen_pt_unregister_vga_regions(d);
 }
 
 /* region mapping */
@@ -693,6 +696,13 @@  static int xen_pt_initfn(PCIDevice *d)
     /* Handle real device's MMIO/PIO BARs */
     xen_pt_register_regions(s);
 
+    /* Setup VGA bios for passthrough GFX */
+    if (xen_pt_setup_vga(&s->real_device) < 0) {
+        XEN_PT_ERR(d, "Setup VGA BIOS of passthrough GFX failed!\n");
+        xen_host_pci_device_put(&s->real_device);
+        return -1;
+    }
+
     /* reinitialize each config register to be emulated */
     if (xen_pt_config_init(s)) {
         XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");
diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
index 942dc60..4d3a18d 100644
--- a/hw/xen/xen_pt.h
+++ b/hw/xen/xen_pt.h
@@ -298,5 +298,9 @@  static inline bool xen_pt_has_msix_mapping(XenPCIPassthroughState *s, int bar)
     return s->msix && s->msix->bar_index == bar;
 }
 
+extern int xen_has_gfx_passthru;
+int xen_pt_register_vga_regions(XenHostPCIDevice *dev);
+int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev);
+int xen_pt_setup_vga(XenHostPCIDevice *dev);
 
 #endif /* !XEN_PT_H */
diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
new file mode 100644
index 0000000..461e526
--- /dev/null
+++ b/hw/xen/xen_pt_graphics.c
@@ -0,0 +1,232 @@ 
+/*
+ * graphics passthrough
+ */
+#include "xen_pt.h"
+#include "xen-host-pci-device.h"
+#include "hw/xen/xen_backend.h"
+
+static int is_vga_passthrough(XenHostPCIDevice *dev)
+{
+    return (xen_has_gfx_passthru
+            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
+}
+
+typedef struct VGARegion {
+    int type;           /* Memory or port I/O */
+    uint64_t guest_base_addr;
+    uint64_t machine_base_addr;
+    uint64_t size;    /* size of the region */
+    int rc;
+} VGARegion;
+
+#define IORESOURCE_IO           0x00000100
+#define IORESOURCE_MEM          0x00000200
+
+static struct VGARegion vga_args[] = {
+    {
+        .type = IORESOURCE_IO,
+        .guest_base_addr = 0x3B0,
+        .machine_base_addr = 0x3B0,
+        .size = 0xC,
+        .rc = -1,
+    },
+    {
+        .type = IORESOURCE_IO,
+        .guest_base_addr = 0x3C0,
+        .machine_base_addr = 0x3C0,
+        .size = 0x20,
+        .rc = -1,
+    },
+    {
+        .type = IORESOURCE_MEM,
+        .guest_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
+        .machine_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
+        .size = 0x20,
+        .rc = -1,
+    },
+};
+
+/*
+ * register VGA resources for the domain with assigned gfx
+ */
+int xen_pt_register_vga_regions(XenHostPCIDevice *dev)
+{
+    int i = 0;
+
+    if (!is_vga_passthrough(dev)) {
+        return 0;
+    }
+
+    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
+        if (vga_args[i].type == IORESOURCE_IO) {
+            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
+                            vga_args[i].guest_base_addr,
+                            vga_args[i].machine_base_addr,
+                            vga_args[i].size, DPCI_ADD_MAPPING);
+        } else {
+            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
+                            vga_args[i].guest_base_addr,
+                            vga_args[i].machine_base_addr,
+                            vga_args[i].size, DPCI_ADD_MAPPING);
+        }
+
+        if (vga_args[i].rc) {
+            XEN_PT_ERR(NULL, "VGA %s mapping failed! (rc: %i)\n",
+                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
+                    vga_args[i].rc);
+            return vga_args[i].rc;
+        }
+    }
+
+    return 0;
+}
+
+/*
+ * unregister VGA resources for the domain with assigned gfx
+ */
+int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
+{
+    int i = 0;
+
+    if (!is_vga_passthrough(dev)) {
+        return 0;
+    }
+
+    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
+        if (vga_args[i].type == IORESOURCE_IO) {
+            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
+                            vga_args[i].guest_base_addr,
+                            vga_args[i].machine_base_addr,
+                            vga_args[i].size, DPCI_REMOVE_MAPPING);
+        } else {
+            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
+                            vga_args[i].guest_base_addr,
+                            vga_args[i].machine_base_addr,
+                            vga_args[i].size, DPCI_REMOVE_MAPPING);
+        }
+
+        if (vga_args[i].rc) {
+            XEN_PT_ERR(NULL, "VGA %s unmapping failed! (rc: %i)\n",
+                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
+                    vga_args[i].rc);
+            return vga_args[i].rc;
+        }
+    }
+
+    return 0;
+}
+
+static int get_vgabios(unsigned char *buf, XenHostPCIDevice *dev)
+{
+    char rom_file[64];
+    FILE *fp;
+    uint8_t val;
+    struct stat st;
+    uint16_t magic = 0;
+    int ret = 0;
+
+    snprintf(rom_file, sizeof(rom_file),
+             "/sys/bus/pci/devices/%04x:%02x:%02x.%d/rom",
+             dev->domain, dev->bus, dev->dev,
+             dev->func);
+
+    if (stat(rom_file, &st)) {
+        return -ENODEV;
+    }
+
+    if (access(rom_file, F_OK)) {
+        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
+                    rom_file);
+        return -ENODEV;
+    }
+
+    /* Write "1" to the ROM file to enable it */
+    fp = fopen(rom_file, "r+");
+    if (fp == NULL) {
+        return -EACCES;
+    }
+    val = 1;
+    if (fwrite(&val, 1, 1, fp) != 1) {
+        XEN_PT_LOG("%s\n", "Failed to enable pci-sysfs rom file");
+        ret = -EIO;
+        goto close_rom;
+    }
+    fseek(fp, 0, SEEK_SET);
+
+    /*
+     * Check if it a real bios extension.
+     * The magic number is 0xAA55.
+     */
+    if (!fread(&magic, sizeof(magic), 1, fp)) {
+        XEN_PT_ERR(NULL, "VGA: can't get magic.\n");
+        ret = -ENODEV;
+        goto close_rom;
+    }
+    if (magic != 0xAA55) {
+        XEN_PT_ERR(NULL, "VGA: wrong magic %x.\n", magic);
+        ret = -ENODEV;
+        goto close_rom;
+    }
+    fseek(fp, 0, SEEK_SET);
+
+    if (!fread(buf, 1, st.st_size, fp)) {
+        XEN_PT_ERR(NULL, "VGA: pci-assign: Cannot read from host %s", rom_file);
+        XEN_PT_LOG(NULL, "VGA: Device option ROM contents are probably invalid "
+                     "(check dmesg).\nSkip option ROM probe with rombar=0, "
+                     "or load from file with romfile=\n");
+    }
+
+close_rom:
+    /* Write "0" to disable ROM */
+    fseek(fp, 0, SEEK_SET);
+    val = 0;
+    if (!fwrite(&val, 1, 1, fp)) {
+        ret = -EIO;
+        XEN_PT_LOG("%s\n", "Failed to disable pci-sysfs rom file");
+    }
+    fclose(fp);
+    return ret;
+}
+
+/* Allocated 128K for the vga bios */
+#define VGA_BIOS_DEFAULT_SIZE (0x20000)
+
+int xen_pt_setup_vga(XenHostPCIDevice *dev)
+{
+    unsigned char *bios = NULL;
+    int bios_size = 0;
+    char *c = NULL;
+    char checksum = 0;
+    int rc = 0;
+
+    if (!is_vga_passthrough(dev)) {
+        return rc;
+    }
+
+    bios = g_malloc0(VGA_BIOS_DEFAULT_SIZE);
+
+    bios_size = get_vgabios(bios, dev);
+    if (bios_size) {
+        XEN_PT_ERR(NULL, "VGA: Error %d getting VBIOS!\n", bios_size);
+        if (bios_size < 0) {
+            XEN_PT_ERR(NULL, "VGA: Error (%s).\n", strerror(bios_size));
+        }
+        rc = -1;
+        goto out;
+    }
+
+    /* Adjust the bios checksum */
+    for (c = (char *)bios; c < ((char *)bios + bios_size); c++) {
+        checksum += *c;
+    }
+    if (checksum) {
+        bios[bios_size - 1] -= checksum;
+        XEN_PT_LOG(NULL, "vga bios checksum is adjusted!\n");
+    }
+
+    /* Currently we fixed this address as a primary. */
+    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
+out:
+    g_free(bios);
+    return rc;
+}
diff --git a/qemu-options.hx b/qemu-options.hx
index ff76ad4..1c77baa 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1066,6 +1066,15 @@  STEXI
 Rotate graphical output some deg left (only PXA LCD).
 ETEXI
 
+DEF("gfx_passthru", 0, QEMU_OPTION_gfx_passthru,
+    "-gfx_passthru   enable Intel IGD passthrough by XEN\n",
+    QEMU_ARCH_ALL)
+STEXI
+@item -gfx_passthru
+@findex -gfx_passthru
+Enable Intel IGD passthrough by XEN
+ETEXI
+
 DEF("vga", HAS_ARG, QEMU_OPTION_vga,
     "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|none]\n"
     "                select video card type\n", QEMU_ARCH_ALL)
diff --git a/vl.c b/vl.c
index a1686ef..c5b572d 100644
--- a/vl.c
+++ b/vl.c
@@ -1418,6 +1418,13 @@  static void configure_msg(QemuOpts *opts)
     enable_timestamp_msg = qemu_opt_get_bool(opts, "timestamp", true);
 }
 
+/* We still need this for compatibility with XEN. */
+int xen_has_gfx_passthru;
+static void xen_gfx_passthru(const char *optarg)
+{
+    xen_has_gfx_passthru = 1;
+}
+
 /***********************************************************/
 /* USB devices */
 
@@ -3945,6 +3952,9 @@  int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_gfx_passthru:
+                xen_gfx_passthru(optarg);
+                break;
             default:
                 os_parse_cmd_args(popt->index, optarg);
             }