lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <20230529204807.z2th6cilnrbzj2e2@skbuf> Date: Mon, 29 May 2023 23:48:07 +0300 From: Vladimir Oltean <vladimir.oltean@....com> To: linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com> Cc: netdev@...r.kernel.org, Rob Herring <robh@...nel.org>, Claudiu Manoil <claudiu.manoil@....com>, Michael Walle <michael@...le.cc>, linux-kernel@...r.kernel.org Subject: Re: [PATCH pci] PCI: don't skip probing entire device if first fn OF node has status = "disabled" Hi Bjorn, On Sun, May 21, 2023 at 02:51:41PM +0300, Vladimir Oltean wrote: > pci_scan_child_bus_extend() calls pci_scan_slot() with devfn > (bus:device:function) being a multiple of 8, i.e. for each unique > device. > > pci_scan_slot() has logic to say that if the function 0 of a device is > absent, the entire device is absent and we can skip the other functions > entirely. Traditionally, this has meant that pci_bus_read_dev_vendor_id() > returns an error code for that function. > > However, since the blamed commit, there is an extra confounding > condition: function 0 of the device exists and has a valid vendor id, > but it is disabled in the device tree. In that case, pci_scan_slot() > would incorrectly skip the entire device instead of just that function. > > Such is the case with the NXP LS1028A SoC, which has an ECAM > for embedded Ethernet (see pcie@...000000 in > arm64/boot/dts/freescale/fsl-ls1028a.dtsi). Each Ethernet port > represents a function within the ENETC ECAM, with function 0 going > to ENETC Ethernet port 0, connected to SERDES port 0 (SGMII or USXGMII). > > When using a SERDES protocol such as 0x9999, all 4 SERDES lanes go to > the Ethernet switch (function 5 on this ECAM) and none go to ENETC > port 0. So, ENETC port 0 needs to have status = "disabled", and embedded > Ethernet takes place just through the other functions (fn 2 is the DSA > master, fn 3 is the MDIO controller, fn 5 is the DSA switch etc). > Contrast this with other SERDES protocols like 0x85bb, where the switch > takes up a single SERDES lane and uses the QSGMII protocol - so ENETC > port 0 also gets access to a SERDES lane. > > Therefore, here, function 0 being unused has nothing to do with the > entire PCI device being unused. > > Add a "bool present_but_skipped" which is propagated from the caller > of pci_set_of_node() all the way to pci_scan_slot(), so that it can > distinguish an error reading the ECAM from a disabled device in the > device tree. > > Fixes: 6fffbc7ae137 ("PCI: Honor firmware's device disabled status") > Signed-off-by: Vladimir Oltean <vladimir.oltean@....com> > --- Do you have some comments here? Thanks, Vladimir
Powered by blists - more mailing lists