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AFNElJ9KeW5Cjnt6ZeC2uR+L0rnVBiWf1GyNxWd2P+SdtR64cWJQ9RM5LMxOmSBcje687Z/fFf/Z65dJW7OEk5Q=@vger.kernel.org X-Gm-Message-State: AOJu0YxuGqsHkJcvyCleUWZ+a3bFg7F5yR2HVodqIACEdxvyKVAt0R6T Y14nA32ZWvEOoHj7r1pzQqtf0RoNdq4fK3WKxdBCGu1FGM+fD4LqjLodij49SSNJQ+Y1AEJfOEw kQAfvXkLMycC53p+hqff3iRpaiw== X-Received: from pfbgt8.prod.google.com ([2002:a05:6a00:4e08:b0:837:aa2e:b191]) (user=joonwonkang job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:12dd:b0:82f:6841:8733 with SMTP id d2e1a72fcca58-8415f62643dmr17524566b3a.48.1779798968505; Tue, 26 May 2026 05:36:08 -0700 (PDT) Date: Tue, 26 May 2026 12:36:06 +0000 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.54.0.746.g67dd491aae-goog Message-ID: <20260526123606.2488278-1-joonwonkang@google.com> Subject: RE: [PATCH v2] iommu: Allow device driver to use its own PASID space for SVA From: Joonwon Kang To: kevin.tian@intel.com, jgg@ziepe.ca Cc: Alexander.Grest@microsoft.com, alexander.shishkin@linux.intel.com, amhetre@nvidia.com, baolu.lu@linux.intel.com, bp@alien8.de, dave.hansen@linux.intel.com, easwar.hariharan@linux.microsoft.com, hpa@zytor.com, iommu@lists.linux.dev, jacob.jun.pan@linux.intel.com, joonwonkang@google.com, joro@8bytes.org, jpb@kernel.org, kas@kernel.org, kees@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com, nicolinc@nvidia.com, peterz@infradead.org, praan@google.com, robin.murphy@arm.com, ryasuoka@redhat.com, smostafa@google.com, sohil.mehta@intel.com, tglx@kernel.org, will@kernel.org, x86@kernel.org, xin@zytor.com Content-Type: text/plain; charset="UTF-8" > > From: Joonwon Kang > > Sent: Tuesday, May 26, 2026 2:58 PM > > > > > On Mon, May 25, 2026 at 03:29:24PM +0000, Joonwon Kang wrote: > > > > > > > Currently, the only known expected user of the new kAPI is our team. > > Since > > > > I test if the patch resolves our problem before sending it, I believe it > > > > should be good enough. Do you mean more than our team by > > "accompanied > > > > users"? > > > > > > He means you cannot send patches like this that only serve OOT drivers > > > to the mainline kernel. > > > > Hmm, it gets back to the chicken-and-egg problem. So, do you recommend > > deferring the patch submission until we find a new in-tree user of the > > new kAPI? I believe we will not make our module in-tree anytime soon. > > Or, is it like I still can send the patch and get it reviewed although we > > cannot merge it to the mainline? > > > > It's not chicken-and-egg problem. Just always send them together. > > so let's wait until your module is ready for in-tree review... Since adding a new kAPI has this limitation, what do you think about the idea of adding a new boot parameter to enforce disabling ENQCMD at EL0 and using the non-global PASID space in that case? This way, I guess we could resolve our issue without having to wait until we have new in-tree users. Do you think it should have the same limitation? Thanks, Joonwon Kang