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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8cc8130a1a3sm139020606d6.37.2026.05.26.05.39.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 May 2026 05:39:04 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wRr3n-0000000DPQA-2CBd; Tue, 26 May 2026 09:39:03 -0300 Date: Tue, 26 May 2026 09:39:03 -0300 From: Jason Gunthorpe To: Joonwon Kang Cc: kevin.tian@intel.com, 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, 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 Subject: Re: [PATCH v2] iommu: Allow device driver to use its own PASID space for SVA Message-ID: <20260526123903.GF2487554@ziepe.ca> References: <20260526123606.2488278-1-joonwonkang@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260526123606.2488278-1-joonwonkang@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260526_053906_443456_FC518BCB X-CRM114-Status: GOOD ( 27.15 ) 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 Tue, May 26, 2026 at 12:36:06PM +0000, Joonwon Kang wrote: > > > 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? No, you can't hack up the kernel for OOT drivers. Jason