Patchwork [V13,3/9] Introduce XenHostPCIDevice to access a pci device on the host.

login
register
mail settings
Submitter Anthony PERARD
Date June 14, 2012, 5:01 p.m.
Message ID <1339693309-15192-4-git-send-email-anthony.perard@citrix.com>
Download mbox | patch
Permalink /patch/164986/
State New
Headers show

Comments

Anthony PERARD - June 14, 2012, 5:01 p.m.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/i386/Makefile.objs    |    1 +
 hw/xen-host-pci-device.c |  396 ++++++++++++++++++++++++++++++++++++++++++++++
 hw/xen-host-pci-device.h |   55 +++++++
 3 files changed, 452 insertions(+), 0 deletions(-)
 create mode 100644 hw/xen-host-pci-device.c
 create mode 100644 hw/xen-host-pci-device.h
Konrad Rzeszutek Wilk - June 14, 2012, 7:53 p.m.
On Thu, Jun 14, 2012 at 06:01:43PM +0100, Anthony PERARD wrote:
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  hw/i386/Makefile.objs    |    1 +
>  hw/xen-host-pci-device.c |  396 ++++++++++++++++++++++++++++++++++++++++++++++
>  hw/xen-host-pci-device.h |   55 +++++++
>  3 files changed, 452 insertions(+), 0 deletions(-)
>  create mode 100644 hw/xen-host-pci-device.c
>  create mode 100644 hw/xen-host-pci-device.h
> 
> diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
> index d43f1df..b719d8e 100644
> --- a/hw/i386/Makefile.objs
> +++ b/hw/i386/Makefile.objs
> @@ -7,6 +7,7 @@ obj-y += debugcon.o multiboot.o
>  obj-y += pc_piix.o
>  obj-y += pc_sysfw.o
>  obj-$(CONFIG_XEN) += xen_platform.o xen_apic.o
> +obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
>  obj-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o kvm/i8259.o kvm/ioapic.o kvm/i8254.o
>  obj-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
>  
> diff --git a/hw/xen-host-pci-device.c b/hw/xen-host-pci-device.c
> new file mode 100644
> index 0000000..e7ff680
> --- /dev/null
> +++ b/hw/xen-host-pci-device.c
> @@ -0,0 +1,396 @@
> +/*
> + * Copyright (C) 2011       Citrix Ltd.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.  See
> + * the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu-common.h"
> +#include "xen-host-pci-device.h"
> +
> +#define XEN_HOST_PCI_MAX_EXT_CAP \
> +    ((PCIE_CONFIG_SPACE_SIZE - PCI_CONFIG_SPACE_SIZE) / (PCI_CAP_SIZEOF + 4))
> +
> +#ifdef XEN_HOST_PCI_DEVICE_DEBUG
> +#  define XEN_HOST_PCI_LOG(f, a...) fprintf(stderr, "%s: " f, __func__, ##a)
> +#else
> +#  define XEN_HOST_PCI_LOG(f, a...) (void)0
> +#endif
> +
> +/*
> + * from linux/ioport.h
> + * IO resources have these defined flags.
> + */
> +#define IORESOURCE_BITS         0x000000ff      /* Bus-specific bits */
> +
> +#define IORESOURCE_TYPE_BITS    0x00000f00      /* Resource type */
> +#define IORESOURCE_IO           0x00000100
> +#define IORESOURCE_MEM          0x00000200
> +
> +#define IORESOURCE_PREFETCH     0x00001000      /* No side effects */
> +#define IORESOURCE_MEM_64       0x00100000
> +
> +static int xen_host_pci_sysfs_path(const XenHostPCIDevice *d,
> +                                   const char *name, char *buf, ssize_t size)
> +{
> +    int rc;
> +
> +    rc = snprintf(buf, size, "/sys/bus/pci/devices/%04x:%02x:%02x.%d/%s",
> +                  d->domain, d->bus, d->dev, d->func, name);
> +
> +    if (rc >= size || rc < 0) {
> +        /* The ouput is truncated or an other error is encountered */
> +        return -ENODEV;
> +    }
> +    return 0;
> +}
> +
> +
> +/* This size should be enough to read the first 7 lines of a ressource file */
> +#define XEN_HOST_PCI_RESSOURCE_BUFFER_SIZE 400
> +static int xen_host_pci_get_resource(XenHostPCIDevice *d)
> +{
> +    int i, rc, fd;
> +    char path[PATH_MAX];
> +    char buf[XEN_HOST_PCI_RESSOURCE_BUFFER_SIZE];
> +    unsigned long long start, end, flags, size;
> +    char *endptr, *s;
> +    uint8_t type;
> +
> +    rc = xen_host_pci_sysfs_path(d, "resource", path, sizeof (path));
> +    if (rc) {
> +        return rc;
> +    }
> +    fd = open(path, O_RDONLY);
> +    if (fd == -1) {
> +        XEN_HOST_PCI_LOG("Error: Can't open %s: %s\n", path, strerror(errno));
> +        return -errno;
> +    }
> +
> +    do {
> +        rc = read(fd, &buf, sizeof (buf) - 1);
> +        if (rc < 0 && errno != EINTR) {
> +            rc = -errno;
> +            goto out;
> +        }
> +    } while (rc < 0);
> +    buf[rc] = 0;
> +    rc = 0;
> +
> +    s = buf;
> +    for (i = 0; i < PCI_NUM_REGIONS; i++) {
> +        type = 0;
> +
> +        start = strtoll(s, &endptr, 16);
> +        if (*endptr != ' ' || s == endptr) {
> +            break;
> +        }
> +        s = endptr + 1;
> +        end = strtoll(s, &endptr, 16);
> +        if (*endptr != ' ' || s == endptr) {
> +            break;
> +        }
> +        s = endptr + 1;
> +        flags = strtoll(s, &endptr, 16);
> +        if (*endptr != '\n' || s == endptr) {
> +            break;
> +        }
> +        s = endptr + 1;
> +
> +        if (start) {
> +            size = end - start + 1;
> +        } else {
> +            size = 0;
> +        }
> +
> +        if (flags & IORESOURCE_IO) {
> +            type |= XEN_HOST_PCI_REGION_TYPE_IO;
> +        }
> +        if (flags & IORESOURCE_MEM) {
> +            type |= XEN_HOST_PCI_REGION_TYPE_MEM;
> +        }
> +        if (flags & IORESOURCE_PREFETCH) {
> +            type |= XEN_HOST_PCI_REGION_TYPE_PREFETCH;
> +        }
> +        if (flags & IORESOURCE_MEM_64) {
> +            type |= XEN_HOST_PCI_REGION_TYPE_MEM_64;
> +        }
> +
> +        if (i < PCI_ROM_SLOT) {
> +            d->io_regions[i].base_addr = start;
> +            d->io_regions[i].size = size;
> +            d->io_regions[i].type = type;
> +            d->io_regions[i].bus_flags = flags & IORESOURCE_BITS;
> +        } else {
> +            d->rom.base_addr = start;
> +            d->rom.size = size;
> +            d->rom.type = type;
> +            d->rom.bus_flags = flags & IORESOURCE_BITS;
> +        }
> +    }
> +    if (i != PCI_NUM_REGIONS) {
> +        /* Invalid format or input to short */
> +        rc = -ENODEV;
> +    }
> +
> +out:
> +    close(fd);
> +    return rc;
> +}
> +
> +/* This size should be enough to read a long from a file */
> +#define XEN_HOST_PCI_GET_VALUE_BUFFER_SIZE 22
> +static int xen_host_pci_get_value(XenHostPCIDevice *d, const char *name,
> +                                  unsigned int *pvalue, int base)
> +{
> +    char path[PATH_MAX];
> +    char buf[XEN_HOST_PCI_GET_VALUE_BUFFER_SIZE];
> +    int fd, rc;
> +    unsigned long value;
> +    char *endptr;
> +
> +    rc = xen_host_pci_sysfs_path(d, name, path, sizeof (path));
> +    if (rc) {
> +        return rc;
> +    }
> +    fd = open(path, O_RDONLY);
> +    if (fd == -1) {
> +        XEN_HOST_PCI_LOG("Error: Can't open %s: %s\n", path, strerror(errno));
> +        return -errno;
> +    }
> +    do {
> +        rc = read(fd, &buf, sizeof (buf) - 1);
> +        if (rc < 0 && errno != EINTR) {
> +            rc = -errno;
> +            goto out;
> +        }
> +    } while (rc < 0);
> +    buf[rc] = 0;
> +    value = strtol(buf, &endptr, base);
> +    if (endptr == buf || *endptr != '\n') {
> +        rc = -1;
> +    } else if ((value == LONG_MIN || value == LONG_MAX) && errno == ERANGE) {
> +        rc = -errno;
> +    } else {
> +        rc = 0;
> +        *pvalue = value;
> +    }
> +out:
> +    close(fd);
> +    return rc;
> +}
> +
> +static inline int xen_host_pci_get_hex_value(XenHostPCIDevice *d,
> +                                             const char *name,
> +                                             unsigned int *pvalue)
> +{
> +    return xen_host_pci_get_value(d, name, pvalue, 16);
> +}
> +
> +static inline int xen_host_pci_get_dec_value(XenHostPCIDevice *d,
> +                                             const char *name,
> +                                             unsigned int *pvalue)
> +{
> +    return xen_host_pci_get_value(d, name, pvalue, 10);
> +}
> +
> +static bool xen_host_pci_dev_is_virtfn(XenHostPCIDevice *d)
> +{
> +    char path[PATH_MAX];
> +    struct stat buf;
> +
> +    if (xen_host_pci_sysfs_path(d, "physfn", path, sizeof (path))) {
> +        return false;
> +    }
> +    return !stat(path, &buf);
> +}
> +
> +static int xen_host_pci_config_open(XenHostPCIDevice *d)
> +{
> +    char path[PATH_MAX];
> +    int rc;
> +
> +    rc = xen_host_pci_sysfs_path(d, "config", path, sizeof (path));
> +    if (rc) {
> +        return rc;
> +    }
> +    d->config_fd = open(path, O_RDWR);
> +    if (d->config_fd < 0) {
> +        return -errno;
> +    }
> +    return 0;
> +}
> +
> +static int xen_host_pci_config_read(XenHostPCIDevice *d,
> +                                    int pos, void *buf, int len)
> +{
> +    int rc;
> +
> +    do {
> +        rc = pread(d->config_fd, buf, len, pos);
> +    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
> +    if (rc != len) {
> +        return -errno;
> +    }
> +    return 0;
> +}
> +
> +static int xen_host_pci_config_write(XenHostPCIDevice *d,
> +                                     int pos, const void *buf, int len)
> +{
> +    int rc;
> +
> +    do {
> +        rc = pwrite(d->config_fd, buf, len, pos);
> +    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
> +    if (rc != len) {
> +        return -errno;
> +    }
> +    return 0;
> +}
> +
> +
> +int xen_host_pci_get_byte(XenHostPCIDevice *d, int pos, uint8_t *p)
> +{
> +    uint8_t buf;
> +    int rc = xen_host_pci_config_read(d, pos, &buf, 1);
> +    if (!rc) {
> +        *p = buf;
> +    }
> +    return rc;
> +}
> +
> +int xen_host_pci_get_word(XenHostPCIDevice *d, int pos, uint16_t *p)
> +{
> +    uint16_t buf;
> +    int rc = xen_host_pci_config_read(d, pos, &buf, 2);
> +    if (!rc) {
> +        *p = le16_to_cpu(buf);
> +    }
> +    return rc;
> +}
> +
> +int xen_host_pci_get_long(XenHostPCIDevice *d, int pos, uint32_t *p)
> +{
> +    uint32_t buf;
> +    int rc = xen_host_pci_config_read(d, pos, &buf, 4);
> +    if (!rc) {
> +        *p = le32_to_cpu(buf);
> +    }
> +    return rc;
> +}
> +
> +int xen_host_pci_get_block(XenHostPCIDevice *d, int pos, uint8_t *buf, int len)
> +{
> +    return xen_host_pci_config_read(d, pos, buf, len);
> +}
> +
> +int xen_host_pci_set_byte(XenHostPCIDevice *d, int pos, uint8_t data)
> +{
> +    return xen_host_pci_config_write(d, pos, &data, 1);
> +}
> +
> +int xen_host_pci_set_word(XenHostPCIDevice *d, int pos, uint16_t data)
> +{
> +    data = cpu_to_le16(data);
> +    return xen_host_pci_config_write(d, pos, &data, 2);
> +}
> +
> +int xen_host_pci_set_long(XenHostPCIDevice *d, int pos, uint32_t data)
> +{
> +    data = cpu_to_le32(data);
> +    return xen_host_pci_config_write(d, pos, &data, 4);
> +}
> +
> +int xen_host_pci_set_block(XenHostPCIDevice *d, int pos, uint8_t *buf, int len)
> +{
> +    return xen_host_pci_config_write(d, pos, buf, len);
> +}
> +
> +int xen_host_pci_find_ext_cap_offset(XenHostPCIDevice *d, uint32_t cap)
> +{
> +    uint32_t header = 0;
> +    int max_cap = XEN_HOST_PCI_MAX_EXT_CAP;
> +    int pos = PCI_CONFIG_SPACE_SIZE;
> +
> +    do {
> +        if (xen_host_pci_get_long(d, pos, &header)) {
> +            break;
> +        }
> +        /*
> +         * If we have no capabilities, this is indicated by cap ID,
> +         * cap version and next pointer all being 0.
> +         */
> +        if (header == 0) {
> +            break;
> +        }
> +
> +        if (PCI_EXT_CAP_ID(header) == cap) {
> +            return pos;
> +        }
> +
> +        pos = PCI_EXT_CAP_NEXT(header);
> +        if (pos < PCI_CONFIG_SPACE_SIZE) {
> +            break;
> +        }
> +
> +        max_cap--;
> +    } while (max_cap > 0);
> +
> +    return -1;
> +}
> +
> +int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
> +                            uint8_t bus, uint8_t dev, uint8_t func)
> +{
> +    unsigned int v;
> +    int rc = 0;
> +
> +    d->config_fd = -1;
> +    d->domain = domain;
> +    d->bus = bus;
> +    d->dev = dev;
> +    d->func = func;
> +
> +    rc = xen_host_pci_config_open(d);
> +    if (rc) {
> +        goto error;
> +    }
> +    rc = xen_host_pci_get_resource(d);
> +    if (rc) {
> +        goto error;
> +    }
> +    rc = xen_host_pci_get_hex_value(d, "vendor", &v);
> +    if (rc) {
> +        goto error;
> +    }
> +    d->vendor_id = v;
> +    rc = xen_host_pci_get_hex_value(d, "device", &v);
> +    if (rc) {
> +        goto error;
> +    }
> +    d->device_id = v;
> +    rc = xen_host_pci_get_dec_value(d, "irq", &v);
> +    if (rc) {
> +        goto error;
> +    }
> +    d->irq = v;
> +    d->is_virtfn = xen_host_pci_dev_is_virtfn(d);
> +
> +    return 0;
> +error:
> +    if (d->config_fd >= 0) {
> +        close(d->config_fd);
> +        d->config_fd = -1;
> +    }
> +    return rc;
> +}
> +
> +void xen_host_pci_device_put(XenHostPCIDevice *d)
> +{
> +    if (d->config_fd >= 0) {
> +        close(d->config_fd);
> +        d->config_fd = -1;
> +    }
> +}
> diff --git a/hw/xen-host-pci-device.h b/hw/xen-host-pci-device.h
> new file mode 100644
> index 0000000..0079dac
> --- /dev/null
> +++ b/hw/xen-host-pci-device.h
> @@ -0,0 +1,55 @@
> +#ifndef XEN_HOST_PCI_DEVICE_H
> +#define XEN_HOST_PCI_DEVICE_H
> +
> +#include "pci.h"
> +
> +enum {
> +    XEN_HOST_PCI_REGION_TYPE_IO = 1 << 1,
> +    XEN_HOST_PCI_REGION_TYPE_MEM = 1 << 2,
> +    XEN_HOST_PCI_REGION_TYPE_PREFETCH = 1 << 3,
> +    XEN_HOST_PCI_REGION_TYPE_MEM_64 = 1 << 4,
> +};
> +
> +typedef struct XenHostPCIIORegion {
> +    pcibus_t base_addr;
> +    pcibus_t size;
> +    uint8_t type;
> +    uint8_t bus_flags; /* Bus-specific bits */
> +} XenHostPCIIORegion;
> +
> +typedef struct XenHostPCIDevice {
> +    uint16_t domain;
> +    uint8_t bus;
> +    uint8_t dev;
> +    uint8_t func;
> +
> +    uint16_t vendor_id;
> +    uint16_t device_id;
> +    int irq;
> +
> +    XenHostPCIIORegion io_regions[PCI_NUM_REGIONS - 1];
> +    XenHostPCIIORegion rom;
> +
> +    bool is_virtfn;
> +
> +    int config_fd;
> +} XenHostPCIDevice;
> +
> +int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
> +                            uint8_t bus, uint8_t dev, uint8_t func);
> +void xen_host_pci_device_put(XenHostPCIDevice *pci_dev);
> +
> +int xen_host_pci_get_byte(XenHostPCIDevice *d, int pos, uint8_t *p);
> +int xen_host_pci_get_word(XenHostPCIDevice *d, int pos, uint16_t *p);
> +int xen_host_pci_get_long(XenHostPCIDevice *d, int pos, uint32_t *p);
> +int xen_host_pci_get_block(XenHostPCIDevice *d, int pos, uint8_t *buf,
> +                           int len);
> +int xen_host_pci_set_byte(XenHostPCIDevice *d, int pos, uint8_t data);
> +int xen_host_pci_set_word(XenHostPCIDevice *d, int pos, uint16_t data);
> +int xen_host_pci_set_long(XenHostPCIDevice *d, int pos, uint32_t data);
> +int xen_host_pci_set_block(XenHostPCIDevice *d, int pos, uint8_t *buf,
> +                           int len);
> +
> +int xen_host_pci_find_ext_cap_offset(XenHostPCIDevice *s, uint32_t cap);
> +
> +#endif /* !XEN_HOST_PCI_DEVICE_H_ */
> -- 
> Anthony PERARD
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Patch

diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
index d43f1df..b719d8e 100644
--- a/hw/i386/Makefile.objs
+++ b/hw/i386/Makefile.objs
@@ -7,6 +7,7 @@  obj-y += debugcon.o multiboot.o
 obj-y += pc_piix.o
 obj-y += pc_sysfw.o
 obj-$(CONFIG_XEN) += xen_platform.o xen_apic.o
+obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
 obj-$(CONFIG_KVM) += kvm/clock.o kvm/apic.o kvm/i8259.o kvm/ioapic.o kvm/i8254.o
 obj-$(CONFIG_SPICE) += qxl.o qxl-logger.o qxl-render.o
 
diff --git a/hw/xen-host-pci-device.c b/hw/xen-host-pci-device.c
new file mode 100644
index 0000000..e7ff680
--- /dev/null
+++ b/hw/xen-host-pci-device.c
@@ -0,0 +1,396 @@ 
+/*
+ * Copyright (C) 2011       Citrix Ltd.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "xen-host-pci-device.h"
+
+#define XEN_HOST_PCI_MAX_EXT_CAP \
+    ((PCIE_CONFIG_SPACE_SIZE - PCI_CONFIG_SPACE_SIZE) / (PCI_CAP_SIZEOF + 4))
+
+#ifdef XEN_HOST_PCI_DEVICE_DEBUG
+#  define XEN_HOST_PCI_LOG(f, a...) fprintf(stderr, "%s: " f, __func__, ##a)
+#else
+#  define XEN_HOST_PCI_LOG(f, a...) (void)0
+#endif
+
+/*
+ * from linux/ioport.h
+ * IO resources have these defined flags.
+ */
+#define IORESOURCE_BITS         0x000000ff      /* Bus-specific bits */
+
+#define IORESOURCE_TYPE_BITS    0x00000f00      /* Resource type */
+#define IORESOURCE_IO           0x00000100
+#define IORESOURCE_MEM          0x00000200
+
+#define IORESOURCE_PREFETCH     0x00001000      /* No side effects */
+#define IORESOURCE_MEM_64       0x00100000
+
+static int xen_host_pci_sysfs_path(const XenHostPCIDevice *d,
+                                   const char *name, char *buf, ssize_t size)
+{
+    int rc;
+
+    rc = snprintf(buf, size, "/sys/bus/pci/devices/%04x:%02x:%02x.%d/%s",
+                  d->domain, d->bus, d->dev, d->func, name);
+
+    if (rc >= size || rc < 0) {
+        /* The ouput is truncated or an other error is encountered */
+        return -ENODEV;
+    }
+    return 0;
+}
+
+
+/* This size should be enough to read the first 7 lines of a ressource file */
+#define XEN_HOST_PCI_RESSOURCE_BUFFER_SIZE 400
+static int xen_host_pci_get_resource(XenHostPCIDevice *d)
+{
+    int i, rc, fd;
+    char path[PATH_MAX];
+    char buf[XEN_HOST_PCI_RESSOURCE_BUFFER_SIZE];
+    unsigned long long start, end, flags, size;
+    char *endptr, *s;
+    uint8_t type;
+
+    rc = xen_host_pci_sysfs_path(d, "resource", path, sizeof (path));
+    if (rc) {
+        return rc;
+    }
+    fd = open(path, O_RDONLY);
+    if (fd == -1) {
+        XEN_HOST_PCI_LOG("Error: Can't open %s: %s\n", path, strerror(errno));
+        return -errno;
+    }
+
+    do {
+        rc = read(fd, &buf, sizeof (buf) - 1);
+        if (rc < 0 && errno != EINTR) {
+            rc = -errno;
+            goto out;
+        }
+    } while (rc < 0);
+    buf[rc] = 0;
+    rc = 0;
+
+    s = buf;
+    for (i = 0; i < PCI_NUM_REGIONS; i++) {
+        type = 0;
+
+        start = strtoll(s, &endptr, 16);
+        if (*endptr != ' ' || s == endptr) {
+            break;
+        }
+        s = endptr + 1;
+        end = strtoll(s, &endptr, 16);
+        if (*endptr != ' ' || s == endptr) {
+            break;
+        }
+        s = endptr + 1;
+        flags = strtoll(s, &endptr, 16);
+        if (*endptr != '\n' || s == endptr) {
+            break;
+        }
+        s = endptr + 1;
+
+        if (start) {
+            size = end - start + 1;
+        } else {
+            size = 0;
+        }
+
+        if (flags & IORESOURCE_IO) {
+            type |= XEN_HOST_PCI_REGION_TYPE_IO;
+        }
+        if (flags & IORESOURCE_MEM) {
+            type |= XEN_HOST_PCI_REGION_TYPE_MEM;
+        }
+        if (flags & IORESOURCE_PREFETCH) {
+            type |= XEN_HOST_PCI_REGION_TYPE_PREFETCH;
+        }
+        if (flags & IORESOURCE_MEM_64) {
+            type |= XEN_HOST_PCI_REGION_TYPE_MEM_64;
+        }
+
+        if (i < PCI_ROM_SLOT) {
+            d->io_regions[i].base_addr = start;
+            d->io_regions[i].size = size;
+            d->io_regions[i].type = type;
+            d->io_regions[i].bus_flags = flags & IORESOURCE_BITS;
+        } else {
+            d->rom.base_addr = start;
+            d->rom.size = size;
+            d->rom.type = type;
+            d->rom.bus_flags = flags & IORESOURCE_BITS;
+        }
+    }
+    if (i != PCI_NUM_REGIONS) {
+        /* Invalid format or input to short */
+        rc = -ENODEV;
+    }
+
+out:
+    close(fd);
+    return rc;
+}
+
+/* This size should be enough to read a long from a file */
+#define XEN_HOST_PCI_GET_VALUE_BUFFER_SIZE 22
+static int xen_host_pci_get_value(XenHostPCIDevice *d, const char *name,
+                                  unsigned int *pvalue, int base)
+{
+    char path[PATH_MAX];
+    char buf[XEN_HOST_PCI_GET_VALUE_BUFFER_SIZE];
+    int fd, rc;
+    unsigned long value;
+    char *endptr;
+
+    rc = xen_host_pci_sysfs_path(d, name, path, sizeof (path));
+    if (rc) {
+        return rc;
+    }
+    fd = open(path, O_RDONLY);
+    if (fd == -1) {
+        XEN_HOST_PCI_LOG("Error: Can't open %s: %s\n", path, strerror(errno));
+        return -errno;
+    }
+    do {
+        rc = read(fd, &buf, sizeof (buf) - 1);
+        if (rc < 0 && errno != EINTR) {
+            rc = -errno;
+            goto out;
+        }
+    } while (rc < 0);
+    buf[rc] = 0;
+    value = strtol(buf, &endptr, base);
+    if (endptr == buf || *endptr != '\n') {
+        rc = -1;
+    } else if ((value == LONG_MIN || value == LONG_MAX) && errno == ERANGE) {
+        rc = -errno;
+    } else {
+        rc = 0;
+        *pvalue = value;
+    }
+out:
+    close(fd);
+    return rc;
+}
+
+static inline int xen_host_pci_get_hex_value(XenHostPCIDevice *d,
+                                             const char *name,
+                                             unsigned int *pvalue)
+{
+    return xen_host_pci_get_value(d, name, pvalue, 16);
+}
+
+static inline int xen_host_pci_get_dec_value(XenHostPCIDevice *d,
+                                             const char *name,
+                                             unsigned int *pvalue)
+{
+    return xen_host_pci_get_value(d, name, pvalue, 10);
+}
+
+static bool xen_host_pci_dev_is_virtfn(XenHostPCIDevice *d)
+{
+    char path[PATH_MAX];
+    struct stat buf;
+
+    if (xen_host_pci_sysfs_path(d, "physfn", path, sizeof (path))) {
+        return false;
+    }
+    return !stat(path, &buf);
+}
+
+static int xen_host_pci_config_open(XenHostPCIDevice *d)
+{
+    char path[PATH_MAX];
+    int rc;
+
+    rc = xen_host_pci_sysfs_path(d, "config", path, sizeof (path));
+    if (rc) {
+        return rc;
+    }
+    d->config_fd = open(path, O_RDWR);
+    if (d->config_fd < 0) {
+        return -errno;
+    }
+    return 0;
+}
+
+static int xen_host_pci_config_read(XenHostPCIDevice *d,
+                                    int pos, void *buf, int len)
+{
+    int rc;
+
+    do {
+        rc = pread(d->config_fd, buf, len, pos);
+    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+    if (rc != len) {
+        return -errno;
+    }
+    return 0;
+}
+
+static int xen_host_pci_config_write(XenHostPCIDevice *d,
+                                     int pos, const void *buf, int len)
+{
+    int rc;
+
+    do {
+        rc = pwrite(d->config_fd, buf, len, pos);
+    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+    if (rc != len) {
+        return -errno;
+    }
+    return 0;
+}
+
+
+int xen_host_pci_get_byte(XenHostPCIDevice *d, int pos, uint8_t *p)
+{
+    uint8_t buf;
+    int rc = xen_host_pci_config_read(d, pos, &buf, 1);
+    if (!rc) {
+        *p = buf;
+    }
+    return rc;
+}
+
+int xen_host_pci_get_word(XenHostPCIDevice *d, int pos, uint16_t *p)
+{
+    uint16_t buf;
+    int rc = xen_host_pci_config_read(d, pos, &buf, 2);
+    if (!rc) {
+        *p = le16_to_cpu(buf);
+    }
+    return rc;
+}
+
+int xen_host_pci_get_long(XenHostPCIDevice *d, int pos, uint32_t *p)
+{
+    uint32_t buf;
+    int rc = xen_host_pci_config_read(d, pos, &buf, 4);
+    if (!rc) {
+        *p = le32_to_cpu(buf);
+    }
+    return rc;
+}
+
+int xen_host_pci_get_block(XenHostPCIDevice *d, int pos, uint8_t *buf, int len)
+{
+    return xen_host_pci_config_read(d, pos, buf, len);
+}
+
+int xen_host_pci_set_byte(XenHostPCIDevice *d, int pos, uint8_t data)
+{
+    return xen_host_pci_config_write(d, pos, &data, 1);
+}
+
+int xen_host_pci_set_word(XenHostPCIDevice *d, int pos, uint16_t data)
+{
+    data = cpu_to_le16(data);
+    return xen_host_pci_config_write(d, pos, &data, 2);
+}
+
+int xen_host_pci_set_long(XenHostPCIDevice *d, int pos, uint32_t data)
+{
+    data = cpu_to_le32(data);
+    return xen_host_pci_config_write(d, pos, &data, 4);
+}
+
+int xen_host_pci_set_block(XenHostPCIDevice *d, int pos, uint8_t *buf, int len)
+{
+    return xen_host_pci_config_write(d, pos, buf, len);
+}
+
+int xen_host_pci_find_ext_cap_offset(XenHostPCIDevice *d, uint32_t cap)
+{
+    uint32_t header = 0;
+    int max_cap = XEN_HOST_PCI_MAX_EXT_CAP;
+    int pos = PCI_CONFIG_SPACE_SIZE;
+
+    do {
+        if (xen_host_pci_get_long(d, pos, &header)) {
+            break;
+        }
+        /*
+         * If we have no capabilities, this is indicated by cap ID,
+         * cap version and next pointer all being 0.
+         */
+        if (header == 0) {
+            break;
+        }
+
+        if (PCI_EXT_CAP_ID(header) == cap) {
+            return pos;
+        }
+
+        pos = PCI_EXT_CAP_NEXT(header);
+        if (pos < PCI_CONFIG_SPACE_SIZE) {
+            break;
+        }
+
+        max_cap--;
+    } while (max_cap > 0);
+
+    return -1;
+}
+
+int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
+                            uint8_t bus, uint8_t dev, uint8_t func)
+{
+    unsigned int v;
+    int rc = 0;
+
+    d->config_fd = -1;
+    d->domain = domain;
+    d->bus = bus;
+    d->dev = dev;
+    d->func = func;
+
+    rc = xen_host_pci_config_open(d);
+    if (rc) {
+        goto error;
+    }
+    rc = xen_host_pci_get_resource(d);
+    if (rc) {
+        goto error;
+    }
+    rc = xen_host_pci_get_hex_value(d, "vendor", &v);
+    if (rc) {
+        goto error;
+    }
+    d->vendor_id = v;
+    rc = xen_host_pci_get_hex_value(d, "device", &v);
+    if (rc) {
+        goto error;
+    }
+    d->device_id = v;
+    rc = xen_host_pci_get_dec_value(d, "irq", &v);
+    if (rc) {
+        goto error;
+    }
+    d->irq = v;
+    d->is_virtfn = xen_host_pci_dev_is_virtfn(d);
+
+    return 0;
+error:
+    if (d->config_fd >= 0) {
+        close(d->config_fd);
+        d->config_fd = -1;
+    }
+    return rc;
+}
+
+void xen_host_pci_device_put(XenHostPCIDevice *d)
+{
+    if (d->config_fd >= 0) {
+        close(d->config_fd);
+        d->config_fd = -1;
+    }
+}
diff --git a/hw/xen-host-pci-device.h b/hw/xen-host-pci-device.h
new file mode 100644
index 0000000..0079dac
--- /dev/null
+++ b/hw/xen-host-pci-device.h
@@ -0,0 +1,55 @@ 
+#ifndef XEN_HOST_PCI_DEVICE_H
+#define XEN_HOST_PCI_DEVICE_H
+
+#include "pci.h"
+
+enum {
+    XEN_HOST_PCI_REGION_TYPE_IO = 1 << 1,
+    XEN_HOST_PCI_REGION_TYPE_MEM = 1 << 2,
+    XEN_HOST_PCI_REGION_TYPE_PREFETCH = 1 << 3,
+    XEN_HOST_PCI_REGION_TYPE_MEM_64 = 1 << 4,
+};
+
+typedef struct XenHostPCIIORegion {
+    pcibus_t base_addr;
+    pcibus_t size;
+    uint8_t type;
+    uint8_t bus_flags; /* Bus-specific bits */
+} XenHostPCIIORegion;
+
+typedef struct XenHostPCIDevice {
+    uint16_t domain;
+    uint8_t bus;
+    uint8_t dev;
+    uint8_t func;
+
+    uint16_t vendor_id;
+    uint16_t device_id;
+    int irq;
+
+    XenHostPCIIORegion io_regions[PCI_NUM_REGIONS - 1];
+    XenHostPCIIORegion rom;
+
+    bool is_virtfn;
+
+    int config_fd;
+} XenHostPCIDevice;
+
+int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
+                            uint8_t bus, uint8_t dev, uint8_t func);
+void xen_host_pci_device_put(XenHostPCIDevice *pci_dev);
+
+int xen_host_pci_get_byte(XenHostPCIDevice *d, int pos, uint8_t *p);
+int xen_host_pci_get_word(XenHostPCIDevice *d, int pos, uint16_t *p);
+int xen_host_pci_get_long(XenHostPCIDevice *d, int pos, uint32_t *p);
+int xen_host_pci_get_block(XenHostPCIDevice *d, int pos, uint8_t *buf,
+                           int len);
+int xen_host_pci_set_byte(XenHostPCIDevice *d, int pos, uint8_t data);
+int xen_host_pci_set_word(XenHostPCIDevice *d, int pos, uint16_t data);
+int xen_host_pci_set_long(XenHostPCIDevice *d, int pos, uint32_t data);
+int xen_host_pci_set_block(XenHostPCIDevice *d, int pos, uint8_t *buf,
+                           int len);
+
+int xen_host_pci_find_ext_cap_offset(XenHostPCIDevice *s, uint32_t cap);
+
+#endif /* !XEN_HOST_PCI_DEVICE_H_ */