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[142.68.128.5]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-476bb82c170sm83084741cf.77.2025.03.19.12.46.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Mar 2025 12:46:09 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1tuzMf-00000000XWX-1ytt; Wed, 19 Mar 2025 16:46:09 -0300 Date: Wed, 19 Mar 2025 16:46:09 -0300 From: Jason Gunthorpe To: Robin Murphy Cc: Pranjal Shrivastava , Joerg Roedel , Will Deacon , Nicolin Chen , Mostafa Saleh , Daniel Mentz , iommu@lists.linux.dev Subject: Re: [RFC PATCH 0/5] iommu/arm-smmu-v3: Implement Runtime/System Sleep ops Message-ID: <20250319194609.GA126678@ziepe.ca> References: <20250319004254.2547950-1-praan@google.com> <5b29ea3b-ba8a-4f7a-b241-4ed5b1985a1f@arm.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5b29ea3b-ba8a-4f7a-b241-4ed5b1985a1f@arm.com> On Wed, Mar 19, 2025 at 06:22:30PM +0000, Robin Murphy wrote: > I don't see SVA and VFIO needing any special considerations, so it might > just be the new vIOMMU stuff which may need to hold PM enabled for the > lifetime of things exposed to userspace. Are you expecting that the VFIO driver, and whatever driver is managing the SVA will keep the power turned on as necessary then? VFIO is not going to work if the SMMU power goes off unexpectedly while the VFIO FD is open. I suppose VFIO also can power off on-demand via userspace asking it. In that case the VM would be co-operating. vcmdq probably needs some suspend resume logic like the normal commandq. viommu I think will only uses STE fields so it should be OK? SVA.. Is similar to VFIO, if the power goes off while the SVA is working that is bad. The SVA requesting driver would have to manage this. HW with userspace command submission probably can't allow the power to go off while command submission is possible. Jason