From 6ad931a232e71620c6dbb8d573ccef51f84f2566 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Mon, 26 Sep 2022 21:15:29 +0800 Subject: [PATCH] iommu/vt-d: Avoid unnecessary global DMA cache invalidation Some VT-d hardware implementations invalidate all DMA remapping hardware translation caches as part of SRTP flow. The VT-d spec adds a ESRTPS (Enhanced Set Root Table Pointer Support, section 11.4.2 in VT-d spec) capability bit to indicate this. With this bit set, software has no need to issue the global invalidation request. Signed-off-by: Lu Baolu Reviewed-by: Jerry Snitselaar Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20220919062523.3438951-3-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/iommu/intel/iommu.c | 7 +++++++ drivers/iommu/intel/iommu.h | 1 + 2 files changed, 8 insertions(+) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 7410d62..2d142ee 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -1239,6 +1239,13 @@ static void iommu_set_root_entry(struct intel_iommu *iommu) raw_spin_unlock_irqrestore(&iommu->register_lock, flag); + /* + * Hardware invalidates all DMA remapping hardware translation + * caches as part of SRTP flow. + */ + if (cap_esrtps(iommu->cap)) + return; + iommu->flush.flush_context(iommu, 0, 0, 0, DMA_CCMD_GLOBAL_INVL); if (sm_supported(iommu)) qi_flush_pasid_cache(iommu, 0, QI_PC_GLOBAL, 0); diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h index bddf6c6..92023df 100644 --- a/drivers/iommu/intel/iommu.h +++ b/drivers/iommu/intel/iommu.h @@ -146,6 +146,7 @@ /* * Decoding Capability Register */ +#define cap_esrtps(c) (((c) >> 63) & 1) #define cap_esirtps(c) (((c) >> 62) & 1) #define cap_fl5lp_support(c) (((c) >> 60) & 1) #define cap_pi_support(c) (((c) >> 59) & 1) -- 2.7.4