iommu/vt-d: Avoid unnecessary global IRTE cache invalidation

Some VT-d hardware implementations invalidate all interrupt remapping
hardware translation caches as part of SIRTP flow. The VT-d spec adds
a ESIRTPS (Enhanced Set Interrupt Remap Table Pointer Support, section
11.4.2 in VT-d spec) capability bit to indicate this.

The spec also states in 11.4.4 that hardware also performs global
invalidation on all interrupt remapping caches as part of Interrupt
Remapping Disable operation if ESIRTPS capability bit is set.

This checks the ESIRTPS capability bit and skip software global cache
invalidation if it's set.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220921065741.3572495-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 99cc75ecac6348445a0275baeba1c1742bd579de..bddf6c69587d33e161c007a83f99cf40189e60b5 100644 (file)
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -146,6 +146,7 @@
 /*
  * Decoding Capability Register
  */
+#define cap_esirtps(c)         (((c) >> 62) & 1)
 #define cap_fl5lp_support(c)   (((c) >> 60) & 1)
 #define cap_pi_support(c)      (((c) >> 59) & 1)
 #define cap_fl1gp_support(c)   (((c) >> 56) & 1)

diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index 2e9683e970f8e50b6f91011803cd40b3be6af01c..5962bb5027d06af10f93c56c54cdb31b541b0178 100644 (file)
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -494,7 +494,8 @@ static void iommu_set_irq_remapping(struct intel_iommu *iommu, int mode)
         * Global invalidation of interrupt entry cache to make sure the
         * hardware uses the new irq remapping table.
         */
-       qi_global_iec(iommu);
+       if (!cap_esirtps(iommu->cap))
+               qi_global_iec(iommu);
 }
 
 static void iommu_enable_irq_remapping(struct intel_iommu *iommu)
@@ -680,7 +681,8 @@ static void iommu_disable_irq_remapping(struct intel_iommu *iommu)
         * global invalidation of interrupt entry cache before disabling
         * interrupt-remapping.
         */
-       qi_global_iec(iommu);
+       if (!cap_esirtps(iommu->cap))
+               qi_global_iec(iommu);
 
        raw_spin_lock_irqsave(&iommu->register_lock, flags);