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Thu, 13 Aug 2026 02:38:37 -0700 From: To: , , , , , , , , , , , , , , , , , , , , CC: , , , , , , , , , , , Subject: [PATCH v4 10/27] vfio/cxl: Reject unsupported decoder topologies at bind Date: Thu, 13 Aug 2026 15:06:14 +0530 Message-ID: <20260813093631.2288172-11-mhonap@nvidia.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260813093631.2288172-1-mhonap@nvidia.com> References: <20260813093631.2288172-1-mhonap@nvidia.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: rnnvmail201.nvidia.com (10.129.68.8) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000C6189:EE_|SA3PR12MB7949:EE_ X-MS-Office365-Filtering-Correlation-Id: eda7ff5f-a05f-41e4-3c01-08def91eb78c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|36860700016|23010399003|82310400026|1800799024|56012099006|10067099003|18002099003|22082099003|11063799006|5023799004|921020; 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Turn that assumption into an explicit refusal at bind rather than a silent misprogramming later. Signed-off-by: Manish Honap --- drivers/vfio/pci/cxl/vfio_cxl_core.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c b/drivers/vfio/pci/cxl/vfio_cxl_core.c index 125e11354a46..7edc53b25576 100644 --- a/drivers/vfio/pci/cxl/vfio_cxl_core.c +++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c @@ -36,10 +36,30 @@ static int vfio_cxl_init_device(struct vfio_pci_core_device *vdev) if (!pdev->hdm) return -EPROBE_DEFER; + /* The guest drives one virtual decoder; multiple are unsupported. */ + if (pdev->hdm->decoder_count != 1) + return -EOPNOTSUPP; + hdm_size = range_len(&pdev->hdm->settings[0].hpa_range); if (!hdm_size) return -ENXIO; + /* Interleaved decoders are unsupported. */ + if (pdev->hdm->settings[0].interleave_ways != 1) + return -EOPNOTSUPP; + + /* + * The guest drives resets through the CXL Device DVSEC and polls the + * shadow for completion. If the host cannot service a function-scoped + * CXL reset (no reset DVSEC, a multifunction device, or no HDM reset + * support), that guest request could never complete, so refuse the + * device rather than advertise a reset the guest would poll on forever. + */ + if (!cxl_reset_capable(pdev)) { + pci_err(pdev, "vfio-cxl: Unsupported device: host cannot service a CXL reset request\n"); + return -EOPNOTSUPP; + } + dvsec = pci_find_dvsec_capability(pdev, PCI_VENDOR_ID_CXL, PCI_DVSEC_CXL_DEVICE); serial = pci_get_dsn(pdev); -- 2.25.1