linux-kernel - [PATCH v1 5/7] iommu/arm-smmu-v3: Skip cd sync if CD table isn't active

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Message-ID: <20230727182647.4106140-6-mshavit@google.com>
Date:   Fri, 28 Jul 2023 02:26:21 +0800
From:   Michael Shavit <mshavit@...gle.com>
To:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>
Cc:     Michael Shavit <mshavit@...gle.com>, jean-philippe@...aro.org,
        nicolinc@...dia.com, jgg@...dia.com, baolu.lu@...ux.intel.com,
        linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1 5/7] iommu/arm-smmu-v3: Skip cd sync if CD table isn't active

This commit explicitly keeps track of whether a CD table is installed in
an STE so that arm_smmu_sync_cd can skip the sync when unnecessary. This
was previously achieved through the domain->devices list, but we are
moving to a model where arm_smmu_sync_cd directly operates on a master
and the master's CD table instead of a domain.

Signed-off-by: Michael Shavit <mshavit@...gle.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 ++++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 654acf6002bf3..af7949b62327b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -987,6 +987,9 @@ static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
 		},
 	};
 
+	if (!smmu_domain->cd_table.installed)
+		return;
+
 	cmds.num = 0;
 
 	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
@@ -1368,6 +1371,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
 				  cd_table->l1_desc ?
 					  STRTAB_STE_0_S1FMT_64K_L2 :
 					  STRTAB_STE_0_S1FMT_LINEAR);
+		cd_table->installed = true;
 	}
 
 	if (s2_cfg) {
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 0e55ca0d40e6b..f301efe90b599 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -599,6 +599,8 @@ struct arm_smmu_ctx_desc_cfg {
 	u8				max_cds_bits;
 	/* Whether CD entries in this table have the stall bit set. */
 	bool				stall_enabled;
+	/* Whether this CD table is installed in any STE */
+	bool                            installed;
 };
 
 struct arm_smmu_s2_cfg {
-- 
2.41.0.585.gd2178a4bd4-goog