vfio/pci: Add emulated PCI IDs

Specifying an emulated PCI vendor/device ID can be useful for testing
various quirk paths, even though the behavior and functionality of
the device with bogus IDs is fully unsupportable.  We need to use a
uint32_t for the vendor/device IDs, even though the registers
themselves are only 16-bit in order to be able to determine whether
the value is valid and user set.

The same support is added for subsystem vendor/device ID, though these
have the possibility of being useful and supported for more than a
testing tool.  An emulated platform might want to impose their own
subsystem IDs or at least hide the physical subsystem ID.  Windows
guests will often reinstall drivers due to a change in subsystem IDs,
something that VM users may want to avoid.  Of course careful
attention would be required to ensure that guest drivers do not rely
on the subsystem ID as a basis for device driver quirks.

All of these options are added using the standard experimental option
prefix and should not be considered stable.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

3 files changed, 59 insertions, 6 deletions

diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index 3717e01a42..2bdaef19f1 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -14,8 +14,6 @@
 #include "trace.h"
 #include "qemu/range.h"
 
-#define PCI_ANY_ID (~0)
-
 /* Use uin32_t for vendor & device so PCI_ANY_ID expands and cannot match hw */
 static bool vfio_pci_is(VFIOPCIDevice *vdev, uint32_t vendor, uint32_t device)
 {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index b944165333..dcabb6d3b3 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2404,8 +2404,53 @@ static int vfio_initfn(PCIDevice *pdev)
     /* QEMU can choose to expose the ROM or not */
     memset(vdev->emulated_config_bits + PCI_ROM_ADDRESS, 0xff, 4);
 
-    vdev->vendor_id = pci_get_word(pdev->config + PCI_VENDOR_ID);
-    vdev->device_id = pci_get_word(pdev->config + PCI_DEVICE_ID);
+    /*
+     * The PCI spec reserves vendor ID 0xffff as an invalid value.  The
+     * device ID is managed by the vendor and need only be a 16-bit value.
+     * Allow any 16-bit value for subsystem so they can be hidden or changed.
+     */
+    if (vdev->vendor_id != PCI_ANY_ID) {
+        if (vdev->vendor_id >= 0xffff) {
+            error_report("vfio: Invalid PCI vendor ID provided");
+            return -EINVAL;
+        }
+        vfio_add_emulated_word(vdev, PCI_VENDOR_ID, vdev->vendor_id, ~0);
+        trace_vfio_pci_emulated_vendor_id(vdev->vbasedev.name, vdev->vendor_id);
+    } else {
+        vdev->vendor_id = pci_get_word(pdev->config + PCI_VENDOR_ID);
+    }
+
+    if (vdev->device_id != PCI_ANY_ID) {
+        if (vdev->device_id > 0xffff) {
+            error_report("vfio: Invalid PCI device ID provided");
+            return -EINVAL;
+        }
+        vfio_add_emulated_word(vdev, PCI_DEVICE_ID, vdev->device_id, ~0);
+        trace_vfio_pci_emulated_device_id(vdev->vbasedev.name, vdev->device_id);
+    } else {
+        vdev->device_id = pci_get_word(pdev->config + PCI_DEVICE_ID);
+    }
+
+    if (vdev->sub_vendor_id != PCI_ANY_ID) {
+        if (vdev->sub_vendor_id > 0xffff) {
+            error_report("vfio: Invalid PCI subsystem vendor ID provided");
+            return -EINVAL;
+        }
+        vfio_add_emulated_word(vdev, PCI_SUBSYSTEM_VENDOR_ID,
+                               vdev->sub_vendor_id, ~0);
+        trace_vfio_pci_emulated_sub_vendor_id(vdev->vbasedev.name,
+                                              vdev->sub_vendor_id);
+    }
+
+    if (vdev->sub_device_id != PCI_ANY_ID) {
+        if (vdev->sub_device_id > 0xffff) {
+            error_report("vfio: Invalid PCI subsystem device ID provided");
+            return -EINVAL;
+        }
+        vfio_add_emulated_word(vdev, PCI_SUBSYSTEM_ID, vdev->sub_device_id, ~0);
+        trace_vfio_pci_emulated_sub_device_id(vdev->vbasedev.name,
+                                              vdev->sub_device_id);
+    }
 
     /* QEMU can change multi-function devices to single function, or reverse */
     vdev->emulated_config_bits[PCI_HEADER_TYPE] =
@@ -2560,6 +2605,12 @@ static Property vfio_pci_dev_properties[] = {
     DEFINE_PROP_BOOL("x-no-kvm-intx", VFIOPCIDevice, no_kvm_intx, false),
     DEFINE_PROP_BOOL("x-no-kvm-msi", VFIOPCIDevice, no_kvm_msi, false),
     DEFINE_PROP_BOOL("x-no-kvm-msix", VFIOPCIDevice, no_kvm_msix, false),
+    DEFINE_PROP_UINT32("x-pci-vendor-id", VFIOPCIDevice, vendor_id, PCI_ANY_ID),
+    DEFINE_PROP_UINT32("x-pci-device-id", VFIOPCIDevice, device_id, PCI_ANY_ID),
+    DEFINE_PROP_UINT32("x-pci-sub-vendor-id", VFIOPCIDevice,
+                       sub_vendor_id, PCI_ANY_ID),
+    DEFINE_PROP_UINT32("x-pci-sub-device-id", VFIOPCIDevice,
+                       sub_device_id, PCI_ANY_ID),
     /*
      * TODO - support passed fds... is this necessary?
      * DEFINE_PROP_STRING("vfiofd", VFIOPCIDevice, vfiofd_name),
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 797e083ca3..f004d52b69 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -20,6 +20,8 @@
 #include "qemu/queue.h"
 #include "qemu/timer.h"
 
+#define PCI_ANY_ID (~0)
+
 struct VFIOPCIDevice;
 
 typedef struct VFIOQuirk {
@@ -116,8 +118,10 @@ typedef struct VFIOPCIDevice {
     EventNotifier err_notifier;
     EventNotifier req_notifier;
     int (*resetfn)(struct VFIOPCIDevice *);
-    uint16_t vendor_id;
-    uint16_t device_id;
+    uint32_t vendor_id;
+    uint32_t device_id;
+    uint32_t sub_vendor_id;
+    uint32_t sub_device_id;
     uint32_t features;
 #define VFIO_FEATURE_ENABLE_VGA_BIT 0
 #define VFIO_FEATURE_ENABLE_VGA (1 << VFIO_FEATURE_ENABLE_VGA_BIT)