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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id af79cd13be357-94047b4f603sm17521885a.40.2026.10.23.06.35.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2026 06:35:47 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xKFQw-0000000Gghx-2aEb; Fri, 23 Oct 2026 10:35:46 -0300 Date: Fri, 23 Oct 2026 10:35:46 -0300 From: Jason Gunthorpe To: Yuho Choi Cc: Tomasz Jeznach , Joerg Roedel , Will Deacon , Robin Murphy , Fangyu Yu , Zong Li , Lu Baolu , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , iommu@lists.linux.dev, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 1/2] iommu/riscv: Keep page table pages when IOTLB invalidation fails Message-ID: <20261023133546.GK3381610@ziepe.ca> References: <20261020053435.1179054-4-oss.patchbox@gmail.com> <20261020053435.1179054-5-oss.patchbox@gmail.com> 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: <20261020053435.1179054-5-oss.patchbox@gmail.com> On Tue, Oct 20, 2026 at 01:34:23AM -0400, Yuho Choi wrote: > riscv_iommu_iotlb_sync() frees the page table pages on gather->freelist > right after riscv_iommu_iotlb_inval(), which does not report whether the > invalidation commands could be queued or whether IOFENCE.C completed. > If either fails, the pages go back to the page allocator while the IOMMU > may still hold cached entries pointing to them, and whatever their next > owner writes there can then be walked as page table entries. Invalidation is not allowed to fail. Drivers always have to free the pages. The system is irrecoverably broken if the iommu driver blows up so much it cannot invalidate. Jason