On 3/4/25 15:17, Corvin Köhne wrote: > On Tue, 2025-03-04 at 01:52 +0800, Tomita Moeko wrote: >> Though GTT Stolen Memory (GSM) is right below Data Stolen Memory (DSM) >> in host address space, direct access to GSM is prohibited, and it is >> not mapped to guest address space. Both host and guest accesses GSM >> indirectly through the second half of MMIO BAR0 (GTTMMADR). >> >> Guest firmware only need to reserve a memory region for DSM and program >> the BDSM register with the base address of that region, that's actually >> what both SeaBIOS[1] and OVMF does now. >> > > When was this merged to OVMF?
It was not merged to upstream OVMF, but how GSM is set up in the widely used IgdAssignmentDxe is the same as SeaBIOS. Will clearify it in v3. Background of how it was not merged to OVMF can be found in edk2 mailing list https://edk2.groups.io/g/bugs/search?q=%5BBug%20935%5D >> [1] >> https://gitlab.com/qemu-project/seabios/-/blob/1.12-stable/src/fw/pciinit.c#L319-332 >> >> Signed-off-by: Tomita Moeko <tomitamo...@gmail.com> >> --- >> hw/vfio/igd.c | 28 +++------------------------- >> 1 file changed, 3 insertions(+), 25 deletions(-) >> >> diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c >> index ca3a32f4f2..dda4c7bb5d 100644 >> --- a/hw/vfio/igd.c >> +++ b/hw/vfio/igd.c >> @@ -112,28 +112,8 @@ static int igd_gen(VFIOPCIDevice *vdev) >> >> #define IGD_GMCH_GEN6_GMS_SHIFT 3 /* SNB_GMCH in i915 */ >> #define IGD_GMCH_GEN6_GMS_MASK 0x1f >> -#define IGD_GMCH_GEN6_GGMS_SHIFT 8 >> -#define IGD_GMCH_GEN6_GGMS_MASK 0x3 >> #define IGD_GMCH_GEN8_GMS_SHIFT 8 /* BDW_GMCH in i915 */ >> #define IGD_GMCH_GEN8_GMS_MASK 0xff >> -#define IGD_GMCH_GEN8_GGMS_SHIFT 6 >> -#define IGD_GMCH_GEN8_GGMS_MASK 0x3 >> - >> -static uint64_t igd_gtt_memory_size(int gen, uint16_t gmch) >> -{ >> - uint64_t ggms; >> - >> - if (gen < 8) { >> - ggms = (gmch >> IGD_GMCH_GEN6_GGMS_SHIFT) & IGD_GMCH_GEN6_GGMS_MASK; >> - } else { >> - ggms = (gmch >> IGD_GMCH_GEN8_GGMS_SHIFT) & IGD_GMCH_GEN8_GGMS_MASK; >> - if (ggms != 0) { >> - ggms = 1ULL << ggms; >> - } >> - } >> - >> - return ggms * MiB; >> -} >> >> static uint64_t igd_stolen_memory_size(int gen, uint32_t gmch) >> { >> @@ -367,7 +347,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int >> nr) >> g_autofree struct vfio_region_info *lpc = NULL; >> PCIDevice *lpc_bridge; >> int ret, gen; >> - uint64_t ggms_size, gms_size; >> + uint64_t gms_size; >> uint64_t *bdsm_size; >> uint32_t gmch; >> Error *err = NULL; >> @@ -527,7 +507,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int >> nr) >> } >> } >> >> - ggms_size = igd_gtt_memory_size(gen, gmch); >> gms_size = igd_stolen_memory_size(gen, gmch); >> >> /* >> @@ -539,7 +518,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int >> nr) >> * config offset 0x5C. >> */ >> bdsm_size = g_malloc(sizeof(*bdsm_size)); >> - *bdsm_size = cpu_to_le64(ggms_size + gms_size); >> + *bdsm_size = cpu_to_le64(gms_size); >> fw_cfg_add_file(fw_cfg_find(), "etc/igd-bdsm-size", >> bdsm_size, sizeof(*bdsm_size)); >> >> @@ -559,6 +538,5 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int >> nr) >> pci_set_quad(vdev->emulated_config_bits + IGD_BDSM_GEN11, ~0); >> } >> >> - trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name, >> - (ggms_size + gms_size) / MiB); >> + trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name, (gms_size / MiB)); >> } >
