[PATCH v2 4/5] iommu/amd: Do not Invalidate IRT when disable IRTE caching

From: Suravee Suthikulpanit
Date: Thu May 18 2023 - 20:56:25 EST


With the Interrupt Remapping Table cache disabled, there is no need to
issue invalidate IRT and wait for its completion. Therefore, add logic
to bypass the operation.

Suggested-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
drivers/iommu/amd/iommu.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 0c4a2796bb0a..51c2b018433d 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1273,12 +1273,24 @@ static void amd_iommu_flush_irt_all(struct amd_iommu *iommu)
u32 devid;
u16 last_bdf = iommu->pci_seg->last_bdf;

+ if (iommu->irtcachedis_enabled)
+ return;
+
for (devid = 0; devid <= last_bdf; devid++)
iommu_flush_irt(iommu, devid);

iommu_completion_wait(iommu);
}

+static void iommu_flush_irt_and_complete(struct amd_iommu *iommu, u16 devid)
+{
+ if (iommu->irtcachedis_enabled)
+ return;
+
+ iommu_flush_irt(iommu, devid);
+ iommu_completion_wait(iommu);
+}
+
void iommu_flush_all_caches(struct amd_iommu *iommu)
{
if (iommu_feature(iommu, FEATURE_IA)) {
@@ -3028,8 +3040,7 @@ static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,

raw_spin_unlock_irqrestore(&table->lock, flags);

- iommu_flush_irt(iommu, devid);
- iommu_completion_wait(iommu);
+ iommu_flush_irt_and_complete(iommu, devid);

return 0;
}
@@ -3048,8 +3059,7 @@ static int modify_irte(struct amd_iommu *iommu,
table->table[index] = irte->val;
raw_spin_unlock_irqrestore(&table->lock, flags);

- iommu_flush_irt(iommu, devid);
- iommu_completion_wait(iommu);
+ iommu_flush_irt_and_complete(iommu, devid);

return 0;
}
@@ -3067,8 +3077,7 @@ static void free_irte(struct amd_iommu *iommu, u16 devid, int index)
iommu->irte_ops->clear_allocated(table, index);
raw_spin_unlock_irqrestore(&table->lock, flags);

- iommu_flush_irt(iommu, devid);
- iommu_completion_wait(iommu);
+ iommu_flush_irt_and_complete(iommu, devid);
}

static void irte_prepare(void *entry,
--
2.31.1