[PATCH v4 2/4] vfio/igd: Refactor option ROM patching

[Tomita Moeko <tomitamoeko@gmail.com>]

Currently the IGD-specific option ROM patching logic is embedded in
vfio_pci_load_rom() rather than igd.c where IGD-specific code lives.
Move this logic into a dedicated vfio_igd_legacy_rom_quirk() in igd.c.
The refactored quirk patches the device ID and checksum on Gen 6~9
devices with legacy VBIOS as option ROM. A new trace event
vfio_pci_igd_vbios_patched is also introduced.

Arguments of vfio_igd_legacy_rom_quirk() are aligned with romfile_fixup
of PCIDevice so that same logic can be reused on romfile later.

Reported-by: K S Maan <kirandeepmaan45@gmail.com>
Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
---
 hw/vfio/igd-stubs.c  |  5 +++++
 hw/vfio/igd.c        | 48 ++++++++++++++++++++++++++++++++++++++++++++
 hw/vfio/pci-quirks.c |  5 +++++
 hw/vfio/pci.c        | 30 +--------------------------
 hw/vfio/pci.h        |  3 +++
 hw/vfio/trace-events |  1 +
 6 files changed, 63 insertions(+), 29 deletions(-)

diff --git a/hw/vfio/igd-stubs.c b/hw/vfio/igd-stubs.c
index f7687d9091..29110f7568 100644
--- a/hw/vfio/igd-stubs.c
+++ b/hw/vfio/igd-stubs.c
@@ -18,3 +18,8 @@ bool vfio_probe_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
 {
     return true;
 }
+
+void vfio_igd_legacy_rom_quirk(PCIDevice *pdev, uint8_t *ptr, uint32_t size)
+{
+    return;
+}
diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index e091f21b6a..f597218164 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -724,3 +724,51 @@ bool vfio_probe_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
 
     return vfio_pci_igd_config_quirk(vdev, errp);
 }
+
+void vfio_igd_legacy_rom_quirk(PCIDevice *pdev, uint8_t *ptr, uint32_t size)
+{
+    VFIOPCIDevice *vdev = VFIO_PCI_DEVICE(pdev);
+    int gen;
+    uint16_t pcir_offset;
+    uint8_t checksum = 0;
+    uint32_t i;
+
+    if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
+        !vfio_is_vga(vdev) || !vdev->vga) {
+        return;
+    }
+
+    /* Only Gen 6~9 devices have legacy VBIOS as Option ROM */
+    gen = igd_gen(vdev);
+    if (gen < 6 || gen > 9) {
+        return;
+    }
+
+    if (pci_get_word(ptr) != 0xaa55) {
+        return;
+    }
+
+    /* Must be a legacy ROM */
+    pcir_offset = pci_get_word(ptr + 0x18);
+    if (pcir_offset + 0x14 >= size || memcmp(ptr + pcir_offset, "PCIR", 4) ||
+        pci_get_byte(ptr + pcir_offset + 0x14) != 0x00) {
+        return;
+    }
+
+    /*
+     * Patch device ID as multiple IGD devices share the same rom with possible
+     * non-matching IDs.
+     */
+    pci_set_word(ptr + pcir_offset + 6, vdev->device_id);
+
+    /*
+     * IGD roms are known to have bogus checksums. No matter we changed the
+     * device ID or not, we need to recalculate the checksum and patch it.
+     */
+    for (i = 0; i < size; i++) {
+        checksum += ptr[i];
+    }
+    ((uint8_t *)ptr)[6] -= checksum;
+
+    trace_vfio_pci_igd_vbios_patched(vdev->vbasedev.name);
+}
diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index bccf31751f..496a79a3ca 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -1592,3 +1592,8 @@ bool vfio_add_virt_caps(VFIOPCIDevice *vdev, Error **errp)
 
     return true;
 }
+
+void vfio_rom_quirk_setup(VFIOPCIDevice *vdev)
+{
+    vfio_igd_legacy_rom_quirk(PCI_DEVICE(vdev), vdev->rom, vdev->rom_size);
+}
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 9c06b25e63..d321e6160a 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -1084,35 +1084,7 @@ static void vfio_pci_load_rom(VFIOPCIDevice *vdev)
         }
     }
 
-    /*
-     * Test the ROM signature against our device, if the vendor is correct
-     * but the device ID doesn't match, store the correct device ID and
-     * recompute the checksum.  Intel IGD devices need this and are known
-     * to have bogus checksums so we can't simply adjust the checksum.
-     */
-    if (pci_get_word(vdev->rom) == 0xaa55 &&
-        pci_get_word(vdev->rom + 0x18) + 8 < vdev->rom_size &&
-        !memcmp(vdev->rom + pci_get_word(vdev->rom + 0x18), "PCIR", 4)) {
-        uint16_t vid, did;
-
-        vid = pci_get_word(vdev->rom + pci_get_word(vdev->rom + 0x18) + 4);
-        did = pci_get_word(vdev->rom + pci_get_word(vdev->rom + 0x18) + 6);
-
-        if (vid == vdev->vendor_id && did != vdev->device_id) {
-            int i;
-            uint8_t csum, *data = vdev->rom;
-
-            pci_set_word(vdev->rom + pci_get_word(vdev->rom + 0x18) + 6,
-                         vdev->device_id);
-            data[6] = 0;
-
-            for (csum = 0, i = 0; i < vdev->rom_size; i++) {
-                csum += data[i];
-            }
-
-            data[6] = -csum;
-        }
-    }
+    vfio_rom_quirk_setup(vdev);
 }
 
 /* "Raw" read of underlying config space. */
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index c3a1f53d35..620baddda2 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -251,10 +251,13 @@ void vfio_bar_quirk_exit(VFIOPCIDevice *vdev, int nr);
 void vfio_bar_quirk_finalize(VFIOPCIDevice *vdev, int nr);
 void vfio_setup_resetfn_quirk(VFIOPCIDevice *vdev);
 bool vfio_add_virt_caps(VFIOPCIDevice *vdev, Error **errp);
+void vfio_rom_quirk_setup(VFIOPCIDevice *vdev);
 void vfio_quirk_reset(VFIOPCIDevice *vdev);
 VFIOQuirk *vfio_quirk_alloc(int nr_mem);
+
 void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr);
 bool vfio_probe_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp);
+void vfio_igd_legacy_rom_quirk(PCIDevice *pdev, uint8_t *ptr, uint32_t size);
 
 extern const PropertyInfo qdev_prop_nv_gpudirect_clique;
 
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 2049159015..7dc334ccb3 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -90,6 +90,7 @@ vfio_pci_igd_bar4_write(const char *name, uint32_t index, uint32_t data, uint32_
 vfio_pci_igd_bdsm_enabled(const char *name, int size) "%s %dMB"
 vfio_pci_igd_host_bridge_enabled(const char *name) "%s"
 vfio_pci_igd_lpc_bridge_enabled(const char *name) "%s"
+vfio_pci_igd_vbios_patched(const char *name) "%s"
 
 # listener.c
 vfio_iommu_map_notify(const char *op, uint64_t iova_start, uint64_t iova_end) "iommu %s @ 0x%"PRIx64" - 0x%"PRIx64
-- 
2.53.0