From: Manoj Vishwanathan <manojvishy@google.com>
To: Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>,
Alex Williamson <alex.williamson@redhat.com>,
linux-arm-kernel@lists.infradead.org
Cc: kvm@vger.kernel.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, David Dillow <dillow@google.com>,
Manoj Vishwanathan <manojvishy@google.com>
Subject: [PATCH v1 2/4] iommu/io-pgtable-arm: Force outer cache for page-level MAIR via user flag
Date: Mon, 26 Aug 2024 07:16:39 +0000 [thread overview]
Message-ID: <20240826071641.2691374-3-manojvishy@google.com> (raw)
In-Reply-To: <20240826071641.2691374-1-manojvishy@google.com>
This change introduces a user-accessible flag that allows controlling
the system-level outer cache behavior for mapped buffers.
By setting this flag, the page-level MAIR attribute will be forced to
use the outer cache, potentially improving performance for frequently
accessed data.
Signed-off-by: Manoj Vishwanathan <manojvishy@google.com>
---
drivers/iommu/io-pgtable-arm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index f5d9fd1f45bf..31dd6203db96 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -471,6 +471,9 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
else if (prot & IOMMU_CACHE)
pte |= (ARM_LPAE_MAIR_ATTR_IDX_CACHE
<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
+ else if (prot & IOMMU_SYS_CACHE)
+ pte |= (ARM_LPAE_MAIR_ATTR_IDX_INC_OCACHE
+ << ARM_LPAE_PTE_ATTRINDX_SHIFT);
}
/*
--
2.46.0.295.g3b9ea8a38a-goog
next prev parent reply other threads:[~2024-08-26 7:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-26 7:16 [PATCH v1 0/4] vfio/iommu: Flag to allow userspace to set DMA buffers system cacheable Manoj Vishwanathan
2024-08-26 7:16 ` [PATCH v1 1/4] iommu: Add IOMMU_SYS_CACHE flag for system cache control Manoj Vishwanathan
2024-08-26 7:16 ` Manoj Vishwanathan [this message]
2024-08-26 7:16 ` [PATCH v1 3/4] vfio: Add VFIO_DMA_MAP_FLAG_SYS_CACHE to control device access to system cache Manoj Vishwanathan
2024-08-26 7:16 ` [PATCH v1 4/4] vfio/type1: Add support for VFIO_DMA_MAP_FLAG_SYS_CACHE Manoj Vishwanathan
2024-08-26 17:04 ` [PATCH v1 0/4] vfio/iommu: Flag to allow userspace to set DMA buffers system cacheable Alex Williamson
2024-08-26 17:36 ` Manoj Vishwanathan
2024-08-26 23:17 ` Jason Gunthorpe
2024-08-27 17:31 ` Robin Murphy
2024-08-28 2:55 ` Manoj Vishwanathan
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