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Subject[PATCH v2] iommu/vt-d: Don't be too aggressive when clearing one context entry
Date
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 <sironi@amazon.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
---
drivers/iommu/intel-iommu.c | 42 ++++++++++++++++++++++++------------------
1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 3e8636f1220e..1aa4ad7974b9 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -974,20 +974,6 @@ static int device_context_mapped(struct intel_iommu *iommu, u8 bus, u8 devfn)
return ret;
}

-static void clear_context_table(struct intel_iommu *iommu, u8 bus, u8 devfn)
-{
- struct context_entry *context;
- unsigned long flags;
-
- spin_lock_irqsave(&iommu->lock, flags);
- context = iommu_context_addr(iommu, bus, devfn, 0);
- if (context) {
- context_clear_entry(context);
- __iommu_flush_cache(iommu, context, sizeof(*context));
- }
- spin_unlock_irqrestore(&iommu->lock, flags);
-}
-
static void free_context_table(struct intel_iommu *iommu)
{
int i;
@@ -2351,13 +2337,33 @@ 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;

- 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);
+ 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);
+ context_clear_entry(context);
+ __iommu_flush_cache(iommu, context, sizeof(*context));
+ spin_unlock_irqrestore(&iommu->lock, flags);
+ 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
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