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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8b53c6b8123sm262540686d6.35.2026.05.09.10.03.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 09 May 2026 10:03:46 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wLl5d-00000001qDf-32X3; Sat, 09 May 2026 14:03:45 -0300 Date: Sat, 9 May 2026 14:03:45 -0300 From: Jason Gunthorpe To: "Tian, Kevin" Cc: Joonwon Kang , "will@kernel.org" , "robin.murphy@arm.com" , "joro@8bytes.org" , "jpb@kernel.org" , "nicolinc@nvidia.com" , "praan@google.com" , "kees@kernel.org" , "amhetre@nvidia.com" , "Alexander.Grest@microsoft.com" , "baolu.lu@linux.intel.com" , "smostafa@google.com" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH RFC] iommu: Enable per-device SSID space for SVA Message-ID: <20260509170345.GE9285@ziepe.ca> References: <20260424085339.3503582-1-joonwonkang@google.com> <20260424133953.GY3611611@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260509_100349_237499_0D10A9C4 X-CRM114-Status: GOOD ( 11.26 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, May 07, 2026 at 08:15:21AM +0000, Tian, Kevin wrote: > if both arch and device support enqcmd-like insn... > > I recalled this was discussed years ago. For devices like this, just > let driver manage its own pasid space then have a new interface > e.g. iommu_sva_bind_device_pasid(dev, mm, pasid) to use the > specified pasid. Yeah, that makes sense. If the driver knows it doesn't use an ENQCMD like programming model at all then it can use this API and it should also avoid programming the MSRs/etc. Jason