Patchwork [v2,7/7] i440fx: add an iommu

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Submitter Avi Kivity
Date Oct. 30, 2012, 11:47 a.m.
Message ID <1351597670-23031-8-git-send-email-avi@redhat.com>
Download mbox | patch
Permalink /patch/195464/
State New
Headers show

Comments

Avi Kivity - Oct. 30, 2012, 11:47 a.m.
This iommu encrypts addresses on the device bus to avoid divuling information
to hackers equipped with bus analyzers.  Following 3DES, addresses are encrypted
multiple times.  A XOR cypher is employed for efficiency.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 hw/piix_pci.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
Blue Swirl - Oct. 30, 2012, 7:18 p.m.
On Tue, Oct 30, 2012 at 11:47 AM, Avi Kivity <avi@redhat.com> wrote:
> This iommu encrypts addresses on the device bus to avoid divuling information
> to hackers equipped with bus analyzers.  Following 3DES, addresses are encrypted
> multiple times.  A XOR cypher is employed for efficiency.

If this is not useful as a test device or other purposes, I'd drop it.

>
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  hw/piix_pci.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 77 insertions(+)
>
> diff --git a/hw/piix_pci.c b/hw/piix_pci.c
> index 9af5847..99601f4 100644
> --- a/hw/piix_pci.c
> +++ b/hw/piix_pci.c
> @@ -30,6 +30,7 @@
>  #include "sysbus.h"
>  #include "range.h"
>  #include "xen.h"
> +#include "exec-memory.h"
>
>  /*
>   * I440FX chipset data sheet.
> @@ -248,6 +249,81 @@ static int i440fx_initfn(PCIDevice *dev)
>      return 0;
>  }
>
> +typedef struct SillyIOMMU SillyIOMMU;
> +
> +struct SillyIOMMU {
> +    MemoryRegion fault;
> +    MemoryRegion l1;
> +    MemoryRegion l2;
> +    hwaddr mask;
> +    hwaddr secret;
> +};
> +
> +static IOMMUTLBEntry silly_l1_translate(MemoryRegion *l1, hwaddr addr)
> +{
> +    SillyIOMMU *s = container_of(l1, SillyIOMMU, l1);
> +    hwaddr xlat = addr ^ s->secret;
> +
> +    printf("l1: %" HWADDR_PRIx " -> %" HWADDR_PRIx "\n", addr, xlat);
> +
> +    return (IOMMUTLBEntry) {
> +        .device_addr = addr & ~s->mask,
> +        .translated_addr = xlat & ~s->mask,
> +        .addr_mask = s->mask,
> +        .perm = { true, true },
> +    };
> +}
> +
> +static MemoryRegionIOMMUOps silly_l1_iommu_ops = {
> +    .translate = silly_l1_translate,
> +};
> +
> +static IOMMUTLBEntry silly_l2_translate(MemoryRegion *l2, hwaddr addr)
> +{
> +    SillyIOMMU *s = container_of(l2, SillyIOMMU, l2);
> +    hwaddr xlat = addr ^ s->secret;
> +
> +    printf("l2: %" HWADDR_PRIx " -> %" HWADDR_PRIx "\n", addr, xlat);
> +
> +    return (IOMMUTLBEntry) {
> +        .device_addr = addr & ~s->mask,
> +        .translated_addr = xlat & ~s->mask,
> +        .addr_mask = s->mask,
> +        .perm = { true, true },
> +    };
> +}
> +
> +static MemoryRegionIOMMUOps silly_l2_iommu_ops = {
> +    .translate = silly_l2_translate,
> +};
> +
> +static MemoryRegion *silly_iommu_new(PCIBus *bus, void *opaque, int devfn)
> +{
> +    SillyIOMMU *s = g_new(SillyIOMMU, 1);
> +    MemoryRegion *sysmem = get_system_memory();
> +
> +    s->mask = (0x1000 << (devfn >> 3)) - 1;
> +    s->secret = ((devfn << 24) | 0x00aabbccdd) & ~s->mask;
> +    memory_region_init(&s->fault, "silly-fault", INT64_MAX);
> +    memory_region_init_iommu(&s->l2, &silly_l2_iommu_ops, sysmem, &s->fault,
> +                             "silly-l2", INT64_MAX);
> +    memory_region_init_iommu(&s->l1, &silly_l1_iommu_ops, &s->l2, &s->fault,
> +                             "silly-l1", INT64_MAX);
> +    return &s->l1;
> +}
> +
> +static void silly_iommu_del(MemoryRegion *l1)
> +{
> +    SillyIOMMU *s = container_of(l1, SillyIOMMU, l1);
> +
> +    memory_region_del_subregion(&s->l2, get_system_memory());
> +    memory_region_del_subregion(&s->l1, &s->l2);
> +    memory_region_destroy(&s->l2);
> +    memory_region_destroy(&s->l1);
> +    memory_region_destroy(&s->fault);
> +    g_free(s);
> +}
> +
>  static PCIBus *i440fx_common_init(const char *device_name,
>                                    PCII440FXState **pi440fx_state,
>                                    int *piix3_devfn,
> @@ -275,6 +351,7 @@ static PCIBus *i440fx_common_init(const char *device_name,
>      s->address_space = address_space_mem;
>      b = pci_bus_new(dev, NULL, pci_address_space,
>                      address_space_io, 0);
> +    pci_setup_iommu(b, silly_iommu_new, silly_iommu_del, NULL);
>      s->bus = b;
>      object_property_add_child(qdev_get_machine(), "i440fx", OBJECT(dev), NULL);
>      qdev_init_nofail(dev);
> --
> 1.7.12
>
Avi Kivity - Oct. 31, 2012, 10:34 a.m.
On 10/30/2012 09:18 PM, Blue Swirl wrote:
> On Tue, Oct 30, 2012 at 11:47 AM, Avi Kivity <avi@redhat.com> wrote:
>> This iommu encrypts addresses on the device bus to avoid divuling information
>> to hackers equipped with bus analyzers.  Following 3DES, addresses are encrypted
>> multiple times.  A XOR cypher is employed for efficiency.
> 
> If this is not useful as a test device or other purposes, I'd drop it.

It's just for demonstrating the API.  I won't propose it for merging.

Patch

diff --git a/hw/piix_pci.c b/hw/piix_pci.c
index 9af5847..99601f4 100644
--- a/hw/piix_pci.c
+++ b/hw/piix_pci.c
@@ -30,6 +30,7 @@ 
 #include "sysbus.h"
 #include "range.h"
 #include "xen.h"
+#include "exec-memory.h"
 
 /*
  * I440FX chipset data sheet.
@@ -248,6 +249,81 @@  static int i440fx_initfn(PCIDevice *dev)
     return 0;
 }
 
+typedef struct SillyIOMMU SillyIOMMU;
+
+struct SillyIOMMU {
+    MemoryRegion fault;
+    MemoryRegion l1;
+    MemoryRegion l2;
+    hwaddr mask;
+    hwaddr secret;
+};
+
+static IOMMUTLBEntry silly_l1_translate(MemoryRegion *l1, hwaddr addr)
+{
+    SillyIOMMU *s = container_of(l1, SillyIOMMU, l1);
+    hwaddr xlat = addr ^ s->secret;
+
+    printf("l1: %" HWADDR_PRIx " -> %" HWADDR_PRIx "\n", addr, xlat);
+
+    return (IOMMUTLBEntry) {
+        .device_addr = addr & ~s->mask,
+        .translated_addr = xlat & ~s->mask,
+        .addr_mask = s->mask,
+        .perm = { true, true },
+    };
+}
+
+static MemoryRegionIOMMUOps silly_l1_iommu_ops = {
+    .translate = silly_l1_translate,
+};
+
+static IOMMUTLBEntry silly_l2_translate(MemoryRegion *l2, hwaddr addr)
+{
+    SillyIOMMU *s = container_of(l2, SillyIOMMU, l2);
+    hwaddr xlat = addr ^ s->secret;
+
+    printf("l2: %" HWADDR_PRIx " -> %" HWADDR_PRIx "\n", addr, xlat);
+
+    return (IOMMUTLBEntry) {
+        .device_addr = addr & ~s->mask,
+        .translated_addr = xlat & ~s->mask,
+        .addr_mask = s->mask,
+        .perm = { true, true },
+    };
+}
+
+static MemoryRegionIOMMUOps silly_l2_iommu_ops = {
+    .translate = silly_l2_translate,
+};
+
+static MemoryRegion *silly_iommu_new(PCIBus *bus, void *opaque, int devfn)
+{
+    SillyIOMMU *s = g_new(SillyIOMMU, 1);
+    MemoryRegion *sysmem = get_system_memory();
+
+    s->mask = (0x1000 << (devfn >> 3)) - 1;
+    s->secret = ((devfn << 24) | 0x00aabbccdd) & ~s->mask;
+    memory_region_init(&s->fault, "silly-fault", INT64_MAX);
+    memory_region_init_iommu(&s->l2, &silly_l2_iommu_ops, sysmem, &s->fault,
+                             "silly-l2", INT64_MAX);
+    memory_region_init_iommu(&s->l1, &silly_l1_iommu_ops, &s->l2, &s->fault,
+                             "silly-l1", INT64_MAX);
+    return &s->l1;
+}
+
+static void silly_iommu_del(MemoryRegion *l1)
+{
+    SillyIOMMU *s = container_of(l1, SillyIOMMU, l1);
+
+    memory_region_del_subregion(&s->l2, get_system_memory());
+    memory_region_del_subregion(&s->l1, &s->l2);
+    memory_region_destroy(&s->l2);
+    memory_region_destroy(&s->l1);
+    memory_region_destroy(&s->fault);
+    g_free(s);
+}
+
 static PCIBus *i440fx_common_init(const char *device_name,
                                   PCII440FXState **pi440fx_state,
                                   int *piix3_devfn,
@@ -275,6 +351,7 @@  static PCIBus *i440fx_common_init(const char *device_name,
     s->address_space = address_space_mem;
     b = pci_bus_new(dev, NULL, pci_address_space,
                     address_space_io, 0);
+    pci_setup_iommu(b, silly_iommu_new, silly_iommu_del, NULL);
     s->bus = b;
     object_property_add_child(qdev_get_machine(), "i440fx", OBJECT(dev), NULL);
     qdev_init_nofail(dev);