From: Joerg Roedel <joro@8bytes.org>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Will Deacon <will@kernel.org>,
ashok.raj@intel.com, kevin.tian@intel.com,
jacob.jun.pan@intel.com, yi.l.liu@intel.com,
sanjay.k.kumar@intel.com, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/5] iommu/vt-d: Remove WO permissions on second-level paging entries
Date: Thu, 4 Mar 2021 13:26:23 +0100 [thread overview]
Message-ID: <20210304122623.GD26414@8bytes.org> (raw)
In-Reply-To: <20210225062654.2864322-3-baolu.lu@linux.intel.com>
On Thu, Feb 25, 2021 at 02:26:51PM +0800, Lu Baolu wrote:
> When the first level page table is used for IOVA translation, it only
> supports Read-Only and Read-Write permissions. The Write-Only permission
> is not supported as the PRESENT bit (implying Read permission) should
> always set. When using second level, we still give separate permissions
> that allows WriteOnly which seems inconsistent and awkward. There is no
> use case we can think off, hence remove that configuration to make it
> consistent.
No use-case for WriteOnly mappings? How about DMA_FROM_DEVICE mappings?
next prev parent reply other threads:[~2021-03-04 12:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 6:26 [PATCH 0/5] iommu/vt-d: Several misc fixes Lu Baolu
2021-02-25 6:26 ` [PATCH 1/5] iommu/vt-d: Report the right page fault address Lu Baolu
2021-02-25 6:26 ` [PATCH 2/5] iommu/vt-d: Remove WO permissions on second-level paging entries Lu Baolu
2021-03-04 12:26 ` Joerg Roedel [this message]
2021-03-08 1:58 ` Lu Baolu
2021-03-08 19:47 ` Raj, Ashok
2021-03-18 9:12 ` Joerg Roedel
2021-03-19 0:24 ` Lu Baolu
2021-02-25 6:26 ` [PATCH 3/5] iommu/vt-d: Invalidate PASID cache when root/context entry changed Lu Baolu
2021-02-25 6:26 ` [PATCH 4/5] iommu/vt-d: Use user privilege for RID2PASID translation Lu Baolu
2021-02-25 6:26 ` [PATCH 5/5] iommu/vt-d: Avoid unnecessary cache flush in pasid entry teardown Lu Baolu
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