From 5faec6a5e2202d3460b6b0550ec4ad897be3c76f Mon Sep 17 00:00:00 2001 From: Tomita Moeko Date: Fri, 7 Mar 2025 02:01:22 +0800 Subject: [PATCH] vfio/igd: Do not include GTT stolen size in etc/igd-bdsm-size MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 IgdAssignmentDxe does now. [1] https://gitlab.com/qemu-project/seabios/-/blob/1.12-stable/src/fw/pciinit.c#L319-332 Signed-off-by: Tomita Moeko Reviewed-by: Alex Williamson Tested-by: Alex Williamson Reviewed-by: Corvin Köhne Link: https://lore.kernel.org/qemu-devel/20250306180131.32970-3-tomitamoeko@gmail.com Signed-off-by: Cédric Le Goater --- 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)); } -- 2.39.5