From: Jason Gunthorpe <jgg@ziepe.ca>
To: Wencheng Yang <east.moutain.yang@gmail.com>
Cc: Joerg Roedel <joro@8bytes.org>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Alex Williamson <alex.williamson@redhat.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH v2] drviers/iommu/amd: support P2P access through IOMMU when SME is enabled
Date: Mon, 20 Jan 2025 09:59:33 -0400 [thread overview]
Message-ID: <20250120135933.GJ674319@ziepe.ca> (raw)
In-Reply-To: <20250117071423.469880-1-east.moutain.yang@gmail.com>
On Fri, Jan 17, 2025 at 03:14:18PM +0800, Wencheng Yang wrote:
> When SME is enabled, memory encryption bit is set in IOMMU page table
> pte entry, it works fine if the pfn of the pte entry is memory.
> However, if the pfn is MMIO address, for example, map other device's mmio
> space to its io page table, in such situation, setting memory encryption
> bit in pte would cause P2P failure.
This doesn't seem entirely right to me, the encrypted bit should flow
in from the entity doing the map and be based on more detailed
knowledge about what is happening.
Not be guessed at inside the iommu.
We have non-encrpyted CPU memory, and (someday) encrypted MMIO.
Jason
next prev parent reply other threads:[~2025-01-20 13:59 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-17 7:14 [PATCH v2] drviers/iommu/amd: support P2P access through IOMMU when SME is enabled Wencheng Yang
2025-01-17 13:44 ` Alex Williamson
2025-01-21 11:07 ` Wencheng Yang
2025-01-21 11:28 ` [PATCH v3 1/3] uapi/linux/vfio:Add VFIO_DMA_MAP_FLAG_MMIO flag Wencheng Yang
2025-01-21 11:28 ` [PATCH v3 2/3] vfio/vfio_iommu_type1:convert VFIO_DMA_MAP_FLAG_MMIO to IOMMU_MMIO flag Wencheng Yang
2025-01-21 11:28 ` [PATCH v3 3/3] iommu/amd:Clear encryption bit if the mapping is for device MMIO Wencheng Yang
2025-01-21 14:05 ` [PATCH v3 1/3] uapi/linux/vfio:Add VFIO_DMA_MAP_FLAG_MMIO flag Jason Gunthorpe
2025-01-21 15:34 ` [PATCH v2] drviers/iommu/amd: support P2P access through IOMMU when SME is enabled Alex Williamson
2025-01-21 20:47 ` Jason Gunthorpe
2025-01-20 13:59 ` Jason Gunthorpe [this message]
2025-01-21 9:27 ` Wencheng Yang
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