6.9-stable review patch. If anyone has any objections, please let me know.
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From: Lu Baolu baolu.lu@linux.intel.com
[ Upstream commit ba00196ca41c4f6d0b0d3c4a6748a133577abe05 ]
A kernel command called igfx_off was introduced in commit <ba39592764ed> ("Intel IOMMU: Intel IOMMU driver"). This command allows the user to disable the IOMMU dedicated to SOC-integrated graphic devices.
Commit <9452618e7462> ("iommu/intel: disable DMAR for g4x integrated gfx") used this mechanism to disable the graphic-dedicated IOMMU for some problematic devices. Later, more problematic graphic devices were added to the list by commit <1f76249cc3beb> ("iommu/vt-d: Declare Broadwell igfx dmar support snafu").
On the other hand, commit <19943b0e30b05> ("intel-iommu: Unify hardware and software passthrough support") uses the identity domain for graphic devices if CONFIG_DMAR_BROKEN_GFX_WA is selected.
+ if (iommu_pass_through) + iommu_identity_mapping = 1; +#ifdef CONFIG_DMAR_BROKEN_GFX_WA + else + iommu_identity_mapping = 2; +#endif ...
static int iommu_should_identity_map(struct pci_dev *pdev, int startup) { + if (iommu_identity_mapping == 2) + return IS_GFX_DEVICE(pdev); ...
In the following driver evolution, CONFIG_DMAR_BROKEN_GFX_WA and quirk_iommu_igfx() are mixed together, causing confusion in the driver's device_def_domain_type callback. On one hand, dmar_map_gfx is used to turn off the graphic-dedicated IOMMU as a workaround for some buggy hardware; on the other hand, for those graphic devices, IDENTITY mapping is required for the IOMMU core.
Commit <4b8d18c0c986> "iommu/vt-d: Remove INTEL_IOMMU_BROKEN_GFX_WA" has removed the CONFIG_DMAR_BROKEN_GFX_WA option, so the IDENTITY_DOMAIN requirement for graphic devices is no longer needed. Therefore, this requirement can be removed from device_def_domain_type() and igfx_off can be made independent.
Fixes: 4b8d18c0c986 ("iommu/vt-d: Remove INTEL_IOMMU_BROKEN_GFX_WA") Signed-off-by: Lu Baolu baolu.lu@linux.intel.com Reviewed-by: Kevin Tian kevin.tian@intel.com Link: https://lore.kernel.org/r/20240428032020.214616-1-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/intel/iommu.c | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index a7ecd90303dc4..e4a03588a8a0f 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -221,12 +221,11 @@ int intel_iommu_sm = IS_ENABLED(CONFIG_INTEL_IOMMU_SCALABLE_MODE_DEFAULT_ON); int intel_iommu_enabled = 0; EXPORT_SYMBOL_GPL(intel_iommu_enabled);
-static int dmar_map_gfx = 1; static int intel_iommu_superpage = 1; static int iommu_identity_mapping; static int iommu_skip_te_disable; +static int disable_igfx_iommu;
-#define IDENTMAP_GFX 2 #define IDENTMAP_AZALIA 4
const struct iommu_ops intel_iommu_ops; @@ -265,7 +264,7 @@ static int __init intel_iommu_setup(char *str) no_platform_optin = 1; pr_info("IOMMU disabled\n"); } else if (!strncmp(str, "igfx_off", 8)) { - dmar_map_gfx = 0; + disable_igfx_iommu = 1; pr_info("Disable GFX device mapping\n"); } else if (!strncmp(str, "forcedac", 8)) { pr_warn("intel_iommu=forcedac deprecated; use iommu.forcedac instead\n"); @@ -2402,9 +2401,6 @@ static int device_def_domain_type(struct device *dev)
if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev)) return IOMMU_DOMAIN_IDENTITY; - - if ((iommu_identity_mapping & IDENTMAP_GFX) && IS_GFX_DEVICE(pdev)) - return IOMMU_DOMAIN_IDENTITY; }
return 0; @@ -2705,9 +2701,6 @@ static int __init init_dmars(void) iommu_set_root_entry(iommu); }
- if (!dmar_map_gfx) - iommu_identity_mapping |= IDENTMAP_GFX; - check_tylersburg_isoch();
ret = si_domain_init(hw_pass_through); @@ -2798,7 +2791,7 @@ static void __init init_no_remapping_devices(void) /* This IOMMU has *only* gfx devices. Either bypass it or set the gfx_mapped flag, as appropriate */ drhd->gfx_dedicated = 1; - if (!dmar_map_gfx) + if (disable_igfx_iommu) drhd->ignored = 1; } } @@ -4875,7 +4868,7 @@ static void quirk_iommu_igfx(struct pci_dev *dev) return;
pci_info(dev, "Disabling IOMMU for graphics on this chipset\n"); - dmar_map_gfx = 0; + disable_igfx_iommu = 1; }
/* G4x/GM45 integrated gfx dmar support is totally busted. */ @@ -4956,8 +4949,8 @@ static void quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
if (!(ggc & GGC_MEMORY_VT_ENABLED)) { pci_info(dev, "BIOS has allocated no shadow GTT; disabling IOMMU for graphics\n"); - dmar_map_gfx = 0; - } else if (dmar_map_gfx) { + disable_igfx_iommu = 1; + } else if (!disable_igfx_iommu) { /* we have to ensure the gfx device is idle before we flush */ pci_info(dev, "Disabling batched IOTLB flush on Ironlake\n"); iommu_set_dma_strict();