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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9479e61c333sm220869985a.3.2026.11.10.05.16.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 05:16:59 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xQlic-00000005geL-2PDT; Tue, 10 Nov 2026 09:16:58 -0400 Date: Tue, 10 Nov 2026 09:16:58 -0400 From: Jason Gunthorpe To: Gong Shuai Cc: tanchi25@mails.ucas.ac.cn, alex@ghiti.fr, andrew.jones@oss.qualcomm.com, anup@brainfault.org, aou@eecs.berkeley.edu, atish.patra@linux.dev, fangyu.yu@linux.alibaba.com, gsh517025@gmail.com, iommu@lists.linux.dev, joro@8bytes.org, kevin.tian@intel.com, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, palmer@dabbelt.com, pbonzini@redhat.com, pjw@kernel.org, robin.murphy@arm.com, seanjc@google.com, tomasz.jeznach@linux.dev, will@kernel.org, wu.fei9@sanechips.com.cn, zhao.qingye@sanechips.com.cn Subject: Re: [RFC PATCH v2 9/9] iommu/riscv: Add riscv_iommu_attach_dev_nested Message-ID: <20261110131658.GW663069@ziepe.ca> References: <20261105144944.10193-1-tanchi25@mails.ucas.ac.cn> <20261110115137.184160-1-gong.shuai@sanechips.com.cn> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110115137.184160-1-gong.shuai@sanechips.com.cn> On Tue, Nov 10, 2026 at 07:51:37PM +0800, Gong Shuai wrote: > 2. Use the guest PSCID directly, but allocate a separate host GSCID for > each vIOMMU. This is the right model. The viommu should allocate the GSCID directly and keep it for the lifetime of the VM. > 3. Share the GSCID and maintain a per-vIOMMU mapping from each guest > PSCID to a host-allocated PSCID. AMD is doing this because they don't have something like a GSCID. Jason