linux-kernel - [PATCH AUTOSEL 5.13 22/88] iommu/amd: Sync once for scatter-gather operations

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Message-Id: <20210910001820.174272-22-sashal@kernel.org>
Date:   Thu,  9 Sep 2021 20:17:14 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Nadav Amit <namit@...are.com>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Jiajun Cao <caojiajun@...are.com>,
        Robin Murphy <robin.murphy@....com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        iommu@...ts.linux-foundation.org, Joerg Roedel <jroedel@...e.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.13 22/88] iommu/amd: Sync once for scatter-gather operations

From: Nadav Amit <namit@...are.com>

[ Upstream commit 3b122a5666cb7c0bb9a439fba0c9a6cf59f999c3 ]

On virtual machines, software must flush the IOTLB after each page table
entry update.

The iommu_map_sg() code iterates through the given scatter-gather list
and invokes iommu_map() for each element in the scatter-gather list,
which calls into the vendor IOMMU driver through iommu_ops callback. As
the result, a single sg mapping may lead to multiple IOTLB flushes.

Fix this by adding amd_iotlb_sync_map() callback and flushing at this
point after all sg mappings we set.

This commit is followed and inspired by commit 933fcd01e97e2
("iommu/vt-d: Add iotlb_sync_map callback").

Cc: Joerg Roedel <joro@...tes.org>
Cc: Will Deacon <will@...nel.org>
Cc: Jiajun Cao <caojiajun@...are.com>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: iommu@...ts.linux-foundation.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Nadav Amit <namit@...are.com>
Link: https://lore.kernel.org/r/20210723093209.714328-7-namit@vmware.com
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/amd/iommu.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 69d441fc1e32..d11386177301 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2028,6 +2028,16 @@ static int amd_iommu_attach_device(struct iommu_domain *dom,
 	return ret;
 }
 
+static void amd_iommu_iotlb_sync_map(struct iommu_domain *dom,
+				     unsigned long iova, size_t size)
+{
+	struct protection_domain *domain = to_pdomain(dom);
+	struct io_pgtable_ops *ops = &domain->iop.iop.ops;
+
+	if (ops->map)
+		domain_flush_np_cache(domain, iova, size);
+}
+
 static int amd_iommu_map(struct iommu_domain *dom, unsigned long iova,
 			 phys_addr_t paddr, size_t page_size, int iommu_prot,
 			 gfp_t gfp)
@@ -2046,10 +2056,8 @@ static int amd_iommu_map(struct iommu_domain *dom, unsigned long iova,
 	if (iommu_prot & IOMMU_WRITE)
 		prot |= IOMMU_PROT_IW;
 
-	if (ops->map) {
+	if (ops->map)
 		ret = ops->map(ops, iova, paddr, page_size, prot, gfp);
-		domain_flush_np_cache(domain, iova, page_size);
-	}
 
 	return ret;
 }
@@ -2197,6 +2205,7 @@ const struct iommu_ops amd_iommu_ops = {
 	.attach_dev = amd_iommu_attach_device,
 	.detach_dev = amd_iommu_detach_device,
 	.map = amd_iommu_map,
+	.iotlb_sync_map	= amd_iommu_iotlb_sync_map,
 	.unmap = amd_iommu_unmap,
 	.iova_to_phys = amd_iommu_iova_to_phys,
 	.probe_device = amd_iommu_probe_device,
-- 
2.30.2