** Description changed: SRU Justification: [ Impact ] - * For non-VFs, function zpci_bus_is_isolated_vf() should return false, - because they aren't VFs. - While zpci_iov_find_parent_pf() specifically checks if a function is a VF, - it then simply returns that there is no parent. + * For non-VFs, function zpci_bus_is_isolated_vf() should return false, + because they aren't VFs. + While zpci_iov_find_parent_pf() specifically checks if a function is a VF, + it then simply returns that there is no parent. - * The simplistic check for a parent then leads to these functions being - confused with isolated VFs, and isolating them on their own domain even - if sibling PFs should share the domain. + * The simplistic check for a parent then leads to these functions being + confused with isolated VFs, and isolating them on their own domain even + if sibling PFs should share the domain. [ Fix ] - * This is fixed by explicitly checking if a function is not a VF. - (Notice that at this point the case where RIDs are ignored is already - handled - and in this case all PCI functions get isolated by being - properly detected in zpci_bus_is_multifunction_root().) + * This is fixed by explicitly checking if a function is not a VF. + (Notice that at this point the case where RIDs are ignored is already + handled - and in this case all PCI functions get isolated by being + properly detected in zpci_bus_is_multifunction_root().) - * 8691abd3afaa "s390/pci: Fix zpci_bus_is_isolated_vf() for non-VFs" + * 8691abd3afaa "s390/pci: Fix zpci_bus_is_isolated_vf() for non-VFs" [ Test Plan ] - * Setup Ubuntu Server (24.04/24.10) for s390x on an IBM z17 - or LinuxONE 5 LPAR. + * Setup Ubuntu Server (24.04/24.10) for s390x on an IBM z17 + or LinuxONE 5 LPAR. - * Have at least two PCIe adapters that support PF/VF (like RoCE Express) - available in that LPAR. + * Have at least two PCIe-adapter-based PCHIDs (physical channel IDs), + that support PF/VF (physical functions) available in this LPAR. + (Like RoCE Express aka ConnectX-6, in NETD mode.) - * Attach multiple PFs of a PF access mode device (notice that this is only - possible with z17 and L1-5 hardware), such as the two PFs of a NETD - to the same LPAR. + * Attach multiple PFs of a PF access mode device (notice that this is only + possible with z17 and L1-5 hardware), such as the two PFs of a NETD + to the same LPAR. - * Observe that they are put into separate PCI domains - instead of sharing the same domain as expected by drivers. + * Observe that they are put into separate PCI domains + instead of sharing the same domain as expected by drivers. - * Due to lack of hardware, the verification will be conducted by IBM. + * A PCI ID has the format "DDDD:BB:ff.d", + whereas the 'DDDD' the PCI Domain is and "ff.d" the PCI Function. - * The fix was discussed upstream and flagged a stable kernel update. + * With a fixed kernel "lspci -vvt" shows + a common PCI Domain (here "[0180:00]") in the PCI ID, + that has two (both) PCI Functions attached (here "00.0" and "00.1"): + # lspci -vvt + -[0180:00]-+-00.0 Mellanox Technologies MT2894 Family [ConnectX-6 Lx] + - \-00.1 Mellanox Technologies MT2894 Family [ConnectX-6 Lx] + + * However, a kernel without the fix included would show here + two separate PCI Domains, instead of a common one. + + * Due to lack of hardware, the verification will be conducted by IBM. + + * The fix was discussed upstream and flagged a stable kernel update. [ Where problems could occur ] - * The modification is limited to one additional if statement - across two lines) in function zpci_bus_is_isolated_vf() - in file arch/s390/pci/pci_bus.c. + * The modification is limited to one additional if statement + across two lines) in function zpci_bus_is_isolated_vf() + in file arch/s390/pci/pci_bus.c. - * Hence the modification will be limited to the s390x-specific parts of - the PCI code in the kernel (sometimes refers to as zPCI), - and will NOT impact any other architecture! + * Hence the modification will be limited to the s390x-specific parts of + the PCI code in the kernel (sometimes refers to as zPCI), + and will NOT impact any other architecture! - * If add. if-statement is not correct and a wrong bool is returned, - function zpci_bus_is_isolated_vf() might report and incorrect zpci_bus - status. Either isolated when it's not or not-isolated when it really is. + * If add. if-statement is not correct and a wrong bool is returned, + function zpci_bus_is_isolated_vf() might report and incorrect zpci_bus + status. Either isolated when it's not or not-isolated when it really is. - * And since the new if statement got inserted before the already existing - 'if (!pdev)', the latter code in function zpci_bus_is_isolated_vf() - might be accidentally skipped. + * And since the new if statement got inserted before the already existing + 'if (!pdev)', the latter code in function zpci_bus_is_isolated_vf() + might be accidentally skipped. - * All this might lead to a similar confusion of the functions in regard to - isolated VFs status and whether isolating them on their own domain even - or not, hence proper testing is needed. + * All this might lead to a similar confusion of the functions in regard to + isolated VFs status and whether isolating them on their own domain even + or not, hence proper testing is needed. [ Other Info ] - * Since the commit got upstream accepted with v6.15-rc1, - 'Questing' is not affected. + * Since the commit got upstream accepted with v6.15-rc1, + 'Questing' is not affected. - * Plucky got fixed with - https://bugs.launchpad.net/bugs/2108854 - (cherry-picked as https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/plucky/commit/?id=58412b2aa12aa43c90d5414e22898a041ec05e8a) + * Plucky got fixed with + https://bugs.launchpad.net/bugs/2108854 + (cherry-picked as https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/plucky/commit/?id=58412b2aa12aa43c90d5414e22898a041ec05e8a) - * Hence the only remaining affected releases, that contain the offending - commit ("s390/pci: Fix handling of isolated VFs"), are oracular and noble. + * Hence the only remaining affected releases, that contain the offending + commit ("s390/pci: Fix handling of isolated VFs"), are oracular and noble. - * Since this issue does not happen (thus cannot be recreated nor tested) - on the IBM Z hardware we have in Canonical, the verification(s) will be - done by IBM on most recent hardware. + * Since this issue does not happen (thus cannot be recreated nor tested) + on the IBM Z hardware we have in Canonical, the verification(s) will be + done by IBM on most recent hardware. __________ s390/pci: Fix zpci_bus_is_isolated_vf() for non-VFs Commit: 8691abd3afaadd816a298503ec1a759df1305d2e ------------------------- For non-VFs, zpci_bus_is_isolated_vf() should return false because they aren't VFs. While zpci_iov_find_parent_pf() specifically checks if a function is a VF, it then simply returns that there is no parent. The simplistic check for a parent then leads to these functions being confused with isolated VFs and isolating them on their own domain even if sibling PFs should share the domain. Fix this by explicitly checking if a function is not a VF. Note also that at this point the case where RIDs are ignored is already handled and in this case all PCI functions get isolated by being detected in zpci_bus_is_multifunction_root(). Cc: [email protected] Fixes: 2844ddbd540f ("s390/pci: Fix handling of isolated VFs") Signed-off-by: Niklas Schnelle <[email protected]> Reviewed-by: Halil Pasic <[email protected]> Signed-off-by: Vasily Gorbik <[email protected]>
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2111599 Title: [UBUNTU 24.04] s390/pci: Fix zpci_bus_is_isolated_vf() for non-VF To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/2111599/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
