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 <[email protected]>
Signed-off-by: Lu Baolu <[email protected]>
Reviewed-by: Jerry Snitselaar <[email protected]>
Reviewed-by: Kevin Tian <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: LuBaolu

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)

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);