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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8b3295db3e3sm428368085a.43.2025.11.21.12.31.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Nov 2025 12:31:40 -0800 (PST) Date: Fri, 21 Nov 2025 15:31:29 -0500 From: Gregory Price To: Terry Bowman Cc: dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, dan.j.williams@intel.com, bhelgaas@google.com, shiju.jose@huawei.com, ming.li@zohomail.com, Smita.KoralahalliChannabasappa@amd.com, rrichter@amd.com, dan.carpenter@linaro.org, PradeepVineshReddy.Kodamati@amd.com, lukas@wunner.de, Benjamin.Cheatham@amd.com, sathyanarayanan.kuppuswamy@linux.intel.com, linux-cxl@vger.kernel.org, alucerop@amd.com, ira.weiny@intel.com, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [RESEND v13 02/25] PCI/CXL: Introduce pcie_is_cxl() Message-ID: References: <20251104170305.4163840-1-terry.bowman@amd.com> <20251104170305.4163840-3-terry.bowman@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251104170305.4163840-3-terry.bowman@amd.com> On Tue, Nov 04, 2025 at 11:02:42AM -0600, Terry Bowman wrote: > CXL and AER drivers need the ability to identify CXL devices. > > Introduce set_pcie_cxl() with logic checking for CXL.mem or CXL.cache > status in the CXL Flexbus DVSEC status register. The CXL Flexbus DVSEC > presence is used because it is required for all the CXL PCIe devices.[1] > ------>8 > > +static void set_pcie_cxl(struct pci_dev *dev) > +{ > + struct pci_dev *parent; ... > + parent = pci_upstream_bridge(dev); > + set_pcie_cxl(parent); > +} ... > +static inline bool pcie_is_cxl(struct pci_dev *pci_dev) > +{ > + return pci_dev->is_cxl; > +} > + We have encountered a crash on QEMU where parent=NULL here static inline struct pci_dev *pci_upstream_bridge(struct pci_dev *dev) { dev = pci_physfn(dev); if (pci_is_root_bus(dev->bus)) return NULL; return dev->bus->self; } ~Gregory