[PATCH] intel-iommu: Don't be too aggressive when clearing one context entry

[Filippo Sironi]

Previously, we were invalidating context cache and IOTLB globally when
clearing one context entry.  This is a tad too aggressive.
Invalidate the context cache and IOTLB for the interested device only.

Signed-off-by: Filippo Sironi <sir...@amazon.de>
Cc: David Woodhouse <d...@amazon.co.uk>
Cc: David Woodhouse <dw...@infradead.org>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: io...@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/iommu/intel-iommu.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 3e8636f1220e..4bf3e59b0929 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2351,13 +2351,32 @@ static inline int domain_pfn_mapping(struct dmar_domain 
*domain, unsigned long i
 
 static void domain_context_clear_one(struct intel_iommu *iommu, u8 bus, u8 
devfn)
 {
+       unsigned long flags;
+       struct context_entry *context;
+       u16 did_old;
+
        if (!iommu)
                return;
 
+       spin_lock_irqsave(&iommu->lock, flags);
+       context = iommu_context_addr(iommu, bus, devfn, 0);
+       if (!context) {
+               spin_unlock_irqrestore(&iommu->lock, flags);
+               return;
+       }
+       did_old = context_domain_id(context);
+       spin_unlock_irqrestore(&iommu->lock, flags);
        clear_context_table(iommu, bus, devfn);
-       iommu->flush.flush_context(iommu, 0, 0, 0,
-                                          DMA_CCMD_GLOBAL_INVL);
-       iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH);
+       iommu->flush.flush_context(iommu,
+                                  did_old,
+                                  (((u16)bus) << 8) | devfn,
+                                  DMA_CCMD_MASK_NOBIT,
+                                  DMA_CCMD_DEVICE_INVL);
+       iommu->flush.flush_iotlb(iommu,
+                                did_old,
+                                0,
+                                0,
+                                DMA_TLB_DSI_FLUSH);
 }
 
 static inline void unlink_domain_info(struct device_domain_info *info)
-- 
2.7.4