Intel IGD makes use of memory allocated and marked reserved by the BIOS as a stolen memory range. For the most part, guest drivers don't make use of this, but our achilles heel is the vBIOS. The vBIOS programs the device to use the host stolen memory range and it's used in the pre-boot environment. Generally the guest won't have access to the host stolen memory area, so these accesses either land in VM memory or unassigned space and generate IOMMU faults. By allocating this range in SeaBIOS and programming it into the device, QEMU (via vfio) can make sure this guest allocated stolen memory range is used instead.
Signed-off-by: Alex Williamson alex.williamson@redhat.com --- src/fw/pciinit.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c index 92170d5..c1ad5d4 100644 --- a/src/fw/pciinit.c +++ b/src/fw/pciinit.c @@ -260,7 +260,7 @@ static void ich9_smbus_setup(struct pci_device *dev, void *arg) static void intel_igd_opregion_setup(struct pci_device *dev, void *arg) { struct romfile_s *file = romfile_find("etc/igd-opregion"); - void *opregion; + void *opregion, *bdsm; u16 bdf = dev->bdf;
if (!file || !file->size) @@ -281,6 +281,17 @@ static void intel_igd_opregion_setup(struct pci_device *dev, void *arg)
dprintf(1, "Intel IGD OpRegion enabled on %02x:%02x.%x\n", pci_bdf_to_bus(bdf), pci_bdf_to_dev(bdf), pci_bdf_to_fn(bdf)); + + bdsm = memalign_high(1024 * 1024, 1024 * 1024); + if (!bdsm) { + warn_noalloc(); + return; + } + + pci_config_writel(bdf, 0x5C, cpu_to_le32((u32)bdsm)); + + dprintf(1, "Allocated 1MB reserved memory for Intel IGD stolen memory at " + "0x%08x\n", (u32)bdsm); }
static const struct pci_device_id pci_device_tbl[] = {