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[34.145.75.25]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-36f6bf827f1sm8989696a91.3.2026.06.05.09.20.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jun 2026 09:20:13 -0700 (PDT) Date: Fri, 5 Jun 2026 16:20:09 +0000 From: Samiullah Khawaja To: Pranjal Shrivastava Cc: iommu@lists.linux.dev, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Joerg Roedel , Will Deacon , Robin Murphy , Baolu Lu , Jason Gunthorpe , Kevin Tian , Bjorn Helgaas Subject: Re: [PATCH v8 4/4] iommu/vt-d: Fail probe on ATS configuration failure Message-ID: References: <20260604182116.3179005-1-praan@google.com> <20260604182116.3179005-5-praan@google.com> Precedence: bulk X-Mailing-List: linux-pci@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: <20260604182116.3179005-5-praan@google.com> On Thu, Jun 04, 2026 at 06:21:16PM +0000, Pranjal Shrivastava wrote: >Update the Intel VT-d driver to handle ATS configuration and enablement >more strictly. Specifically, update the device probe to fail if >pci_prepare_ats() returns an error. This ensures that any ATS-capable >master reaching the attach phase is guaranteed to have a valid config. > >Additionally, update iommu_enable_pci_ats() to WARN() if pci_enable_ats >fails. Since earlier checks in the probe phase preclude config-related >failures, any failure during hardware enablement is considered a kernel >bug. > >Reviewed-by: Lu Baolu >Reviewed-by: Kevin Tian >Signed-off-by: Pranjal Shrivastava >--- > drivers/iommu/intel/iommu.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > >diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >index 849d06dfe1ae..f39451323553 100644 >--- a/drivers/iommu/intel/iommu.c >+++ b/drivers/iommu/intel/iommu.c >@@ -876,8 +876,14 @@ static void iommu_enable_pci_ats(struct device_domain_info *info) > if (!pci_ats_page_aligned(pdev)) > return; > >- if (!pci_enable_ats(pdev, VTD_PAGE_SHIFT)) >- info->ats_enabled = 1; >+ /* >+ * pci_enable_ats() should not fail here because earlier checks >+ * have already verified support and configuration. >+ */ >+ if (WARN_ON(pci_enable_ats(pdev, VTD_PAGE_SHIFT))) >+ return; >+ >+ info->ats_enabled = 1; > } > > static void iommu_disable_pci_ats(struct device_domain_info *info) >@@ -3292,7 +3298,10 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev) > > dev_iommu_priv_set(dev, info); > if (pdev && pci_ats_supported(pdev)) { >- pci_prepare_ats(pdev, VTD_PAGE_SHIFT); >+ ret = pci_prepare_ats(pdev, VTD_PAGE_SHIFT); >+ if (ret) >+ goto free; >+ > ret = device_rbtree_insert(iommu, info); > if (ret) > goto free; >-- >2.54.0.1032.g2f8565e1d1-goog > Reviewed-by: Samiullah Khawaja