From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Kalra, Ashish" <ashish.kalra@amd.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
joro@8bytes.org, robin.murphy@arm.com, thomas.lendacky@amd.com,
vasant.hegde@amd.com, jon.grimm@amd.com
Subject: Re: [PATCH 1/4] iommu/amd: Introduce Protection-domain flag VFIO
Date: Fri, 20 Jan 2023 13:50:25 -0400 [thread overview]
Message-ID: <Y8rUYTjVhksAu+i9@ziepe.ca> (raw)
In-Reply-To: <1ba09b11-8a07-24dd-a99f-eeacb2f5c96c@amd.com>
On Fri, Jan 20, 2023 at 11:01:21AM -0600, Kalra, Ashish wrote:
> We basically get the RMP #PF from the IOMMU because there is a page size
> mismatch between the RMP table and the IOMMU page table. The RMP table's
> large page entry has been smashed to 4K PTEs to handle page state change to
> shared on 4K mappings, so this change has to be synced up with the IOMMU
> page table, otherwise there is now a page size mismatch between RMP table
> and IOMMU page table which causes the RMP #PF.
I understand that, you haven't answered my question:
Why is the IOMMU being programmed with pages it cannot access in the
first place?
Don't do that is the obvious solution there, and preserves huge page
IO performance.
Jason
next prev parent reply other threads:[~2023-01-20 17:50 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-10 14:31 [PATCH 0/4] iommu/amd: Force SNP-enabled VFIO domain to 4K page size Suravee Suthikulpanit
2023-01-10 14:31 ` [PATCH 1/4] iommu/amd: Introduce Protection-domain flag VFIO Suravee Suthikulpanit
2023-01-11 3:31 ` kernel test robot
2023-01-13 15:33 ` Jason Gunthorpe
2023-01-19 8:54 ` Kalra, Ashish
2023-01-19 17:44 ` Jason Gunthorpe
2023-01-20 15:12 ` Kalra, Ashish
2023-01-20 16:13 ` Jason Gunthorpe
2023-01-20 17:01 ` Kalra, Ashish
2023-01-20 17:50 ` Jason Gunthorpe [this message]
2023-01-20 19:55 ` Kalra, Ashish
2023-01-20 22:42 ` Tom Lendacky
2023-01-21 0:09 ` Jason Gunthorpe
2023-01-10 14:31 ` [PATCH 2/4] iommu/amd: Introduce structure amd_iommu_svm_ops.is_snp_guest() Suravee Suthikulpanit
2023-01-10 14:31 ` [PATCH 3/4] iommu: Introduce IOMMU call-back for processing struct KVM assigned to VFIO Suravee Suthikulpanit
2023-01-10 15:11 ` Robin Murphy
2023-01-17 4:20 ` Suthikulpanit, Suravee
2023-01-17 12:51 ` Robin Murphy
2023-01-13 15:35 ` Jason Gunthorpe
2023-01-17 5:31 ` Suthikulpanit, Suravee
2023-01-17 14:19 ` Jason Gunthorpe
2023-01-10 14:31 ` [PATCH 4/4] iommu/amd: Force SNP-enabled VFIO domain to 4K page size Suravee Suthikulpanit
2023-01-17 13:10 ` Eric van Tassell
2023-01-16 13:17 ` [PATCH 0/4] " Eric van Tassell
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