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[34.145.75.25]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84564e9dab2sm8963719b3a.41.2026.06.22.17.36.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jun 2026 17:36:28 -0700 (PDT) Date: Tue, 23 Jun 2026 00:36:25 +0000 From: Samiullah Khawaja To: Baolu Lu Cc: David Woodhouse , Joerg Roedel , Will Deacon , Jason Gunthorpe , Robin Murphy , Kevin Tian , Alex Williamson , Shuah Khan , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Pratyush Yadav , Pasha Tatashin , David Matlack , Andrew Morton , Pranjal Shrivastava , Vipin Sharma Subject: Re: [PATCH v3 13/18] iommu/vt-d: preserve PASID table of preserved device Message-ID: References: <20260614233728.2212104-1-skhawaja@google.com> <20260614233728.2212104-14-skhawaja@google.com> <8b1076ea-022c-42f2-8fbb-f55cd30b4b3d@linux.intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <8b1076ea-022c-42f2-8fbb-f55cd30b4b3d@linux.intel.com> On Mon, Jun 22, 2026 at 02:01:09PM +0800, Baolu Lu wrote: >On 6/15/26 07:37, Samiullah Khawaja wrote: >>diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c >>index 89541b74ab8c..5cac8e95f73b 100644 >>--- a/drivers/iommu/intel/pasid.c >>+++ b/drivers/iommu/intel/pasid.c >>@@ -60,8 +60,11 @@ int intel_pasid_alloc_table(struct device *dev) >> size = max_pasid >> (PASID_PDE_SHIFT - 3); >> order = size ? get_order(size) : 0; >>- dir = iommu_alloc_pages_node_sz(info->iommu->node, GFP_KERNEL, >>- 1 << (order + PAGE_SHIFT)); >>+ >>+ dir = intel_pasid_try_restore_table(dev, 1 << (order + PAGE_SHIFT + 3)); >>+ if (!dir) >>+ dir = iommu_alloc_pages_node_sz(info->iommu->node, GFP_KERNEL, >>+ 1 << (order + PAGE_SHIFT)); >> if (!dir) { >> kfree(pasid_table); >> return -ENOMEM; > >This reads as if PASID table restoration fails, it tries to allocate a >native PASID table instead. This doesn't match my understanding. It >would be a disaster, and the system should panic if the table >restoration fails. Or is there something I'm overlooking? Your understanding is correct, and that is exactly what intel_pasid_try_restore_table() does if the device state was preserved. If the restoration fails, it fails hard with a panic. The reason I have _try_ in the name is to account for devices that simply have no preserved state to begin with. In that case, a new PASID table needs to be allocated. I agree the naming makes it sound like we ignore restoration failures. I will rename the function to make this less confusing in v4. > >Thanks, >baolu