Messages in this thread | | | Date | Wed, 13 Dec 2023 11:02:07 +0800 | Subject | Re: [PATCH v2 4/6] iommu/vt-d: Remove 1:1 mappings from identity domain | From | Baolu Lu <> |
| |
On 12/13/23 11:04 AM, Tian, Kevin wrote: >> From: Baolu Lu<baolu.lu@linux.intel.com> >> Sent: Wednesday, December 13, 2023 10:44 AM >> >> On 12/13/23 10:20 AM, Tian, Kevin wrote: >>>>> if (!dmar_map_gfx) >>>>> iommu_identity_mapping |= IDENTMAP_GFX; >>>> So with above cleaned up, we have no need to worry about drivers that >>>> are not capable of handling remapped dma address any more. >>>> >>>> Did I miss anything? >>> I prefer to removing IDENTMAP_GFX in this series and put a comment >>> explaining why Azalia device has no problem. >>> >>> Then send a separate patch to remove the GFX workaround option. >>> If there is any valid usage still relying on that, it's easy to revert. >> Agreed. We should be more cautious. Perhaps I will postpone this series >> to a time when we are sure that graphic drivers are okay with this >> change. As a first step, perhaps we can make a change to remove the >> workaround for graphic drivers, so that any hidden bugs in the graphic >> driver could be reported. >> >> The patch looks like, >> >> iommu/vt-d: Remove INTEL_IOMMU_BROKEN_GFX_WA >> >> Commit 62edf5dc4a524 ("intel-iommu: Restore DMAR_BROKEN_GFX_WA >> option for >> broken graphics drivers") was introduced 24 years ago as a temporary >> workaround for graphics drivers that used physical addresses for DMA and >> avoided DMA APIs. This workaround was disabled by default. >> >> As 24 years have passed, it is expected that graphics driver developers >> have migrated their drivers to use kernel DMA APIs. Therefore, this >> workaround is no longer required and could been removed. > and igfx_off option is still available just in case.
Yeah!
> >> Suggested-by: Kevin Tian<kevin.tian@intel.com> >> Signed-off-by: Lu Baolu<baolu.lu@linux.intel.com> >> --- >> drivers/iommu/intel/iommu.c | 10 ---------- >> drivers/iommu/intel/Kconfig | 11 ----------- >> 2 files changed, 21 deletions(-) >> >> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >> index 84b78e42a470..27b8638291f2 100644 >> --- a/drivers/iommu/intel/iommu.c >> +++ b/drivers/iommu/intel/iommu.c >> @@ -2357,9 +2357,6 @@ 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; >> @@ -2660,13 +2657,6 @@ static int __init init_dmars(void) >> iommu_set_root_entry(iommu); >> } >> >> -#ifdef CONFIG_INTEL_IOMMU_BROKEN_GFX_WA >> - dmar_map_gfx = 0; >> -#endif >> - >> - if (!dmar_map_gfx) >> - iommu_identity_mapping |= IDENTMAP_GFX; >> - > let's remove IDENTMAP_GFX (and all its references) in a separate patch. > > this patch is for removing the workaround option. > > another patch removes IDENTMAP_GFX as it's meaningless when > dmar_map_gfx simply implies disabling the gfx iommu.
Okay, it's fine to me.
Best regards, baolu
| |