From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Kevin Tian <kevin.tian@intel.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
Lu Baolu <baolu.lu@linux.intel.com>
Subject: [PATCH 1/1] iommu: Avoid unnecessary cache invalidations
Date: Thu, 26 Oct 2023 16:49:42 +0800 [thread overview]
Message-ID: <20231026084942.17387-1-baolu.lu@linux.intel.com> (raw)
The iommu_create_device_direct_mappings() only needs to flush the caches
when the mappings are changed in the affected domain. This is not true
for non-DMA domains, or for devices attached to the domain that have no
reserved regions. To avoid unnecessary cache invalidations, add a check
before iommu_flush_iotlb_all().
Fixes: a48ce36e2786 ("iommu: Prevent RESV_DIRECT devices from blocking domains")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/iommu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 00d0a2b5d7dc..0cb676590bfa 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1114,7 +1114,8 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
}
- iommu_flush_iotlb_all(domain);
+ if (!list_empty(&mappings) && iommu_is_dma_domain(domain))
+ iommu_flush_iotlb_all(domain);
out:
iommu_put_resv_regions(dev, &mappings);
--
2.34.1
next reply other threads:[~2023-10-26 8:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-26 8:49 Lu Baolu [this message]
2023-10-27 4:30 ` [PATCH 1/1] iommu: Avoid unnecessary cache invalidations Henry Willard
2023-10-27 6:57 ` Joerg Roedel
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