From: Lu Baolu Date: Wed, 14 Jun 2023 02:47:05 +0000 (+0800) Subject: iommu/vt-d: Remove commented-out code X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b4da4e112ade4e7c59cf915c702b14d69b528824;p=linux.git iommu/vt-d: Remove commented-out code These lines of code were commented out when they were first added in commit ba39592764ed ("Intel IOMMU: Intel IOMMU driver"). We do not want to restore them because the VT-d spec has deprecated the read/write draining hit. VT-d spec (section 11.4.2): " Hardware implementation with Major Version 2 or higher (VER_REG), always performs required drain without software explicitly requesting a drain in IOTLB invalidation. This field is deprecated and hardware will always report it as 1 to maintain backward compatibility with software. " Remove the code to make the code cleaner. Signed-off-by: Lu Baolu Reviewed-by: Jerry Snitselaar Link: https://lore.kernel.org/r/20230609060514.15154-1-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 4c0b7424c45ee..e5c111ff4dd95 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -1312,15 +1312,7 @@ static void __iommu_flush_iotlb(struct intel_iommu *iommu, u16 did, iommu->name, type); return; } - /* Note: set drain read/write */ -#if 0 - /* - * This is probably to be super secure.. Looks like we can - * ignore it without any impact. - */ - if (cap_read_drain(iommu->cap)) - val |= DMA_TLB_READ_DRAIN; -#endif + if (cap_write_drain(iommu->cap)) val |= DMA_TLB_WRITE_DRAIN;