This looks similar to the following kernel thread https://lore.kernel.org/lkml/a60333b9-6b42-4730-6509-cf1a0cd5c...@citrix.com/T/ > Apparently "size 832 != kernel_size 0" so let the debugging continue... [...] > So we've actually found and fixed the issue, but XSAVE and therefore automatically gnarly. > https://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=c3bd0b83ea5b7c0da6542687436042eeea1e7909 > >There is no real hardware with XSAVEC but not XSAVES; the spec does try >to distinguish the two, and it's useful for virt to offer XSAVEC without >XSAVES. > >CPUID.0xd[1].ebx is spec'd as the total size for XSAVES of all current >XCR0|XSS states. This is known dodgy already for native, as it leaks >the current MSR_XSS setting into userspace. > >I had written the logic originally to hide this dynamic field if XSAVES >wasn't enumerated, but Linux now uses it if XSAVEC is enumerated, to >cross-check what it can see elsewhere in the CPUID state.
On a guest VM running the same hypervisor, we see the xsavec feature is present but not xsaves. https://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=c3bd0b83ea5b7c0da6542687436042eeea1e7909 mentions > While the SDM isn't very clear about this, our present behavior make > Linux 5.19 unhappy. As of commit 8ad7e8f69695 ("x86/fpu/xsave: Support > XSAVEC in the kernel") they're using this CPUID output also to size > the compacted area used by XSAVEC. Getting back zero there isn't really > liked, yet for PV that's the default on capable hardware: XSAVES isn't > exposed to PV domains. > > Considering that the size reported is that of the compacted save area, > I view Linux'es assumption as appropriate (short of the SDM properly > considering the case). Therefore we need to populate the field also when > only XSAVEC is supported for a guest. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2019108 Title: XSAVE consistency problem preventing avx on KVM guests Status in linux package in Ubuntu: Incomplete Bug description: On an openstack KVM guest VM the following kernel message is displayed: "XSAVE consistency problem: size 2560 != kernel_size 0" (see further traces collected through "ubuntu-bug linux" command) As a result, the avx feature isn't enabled in the kernel, failing some programs that require it (e.g mongodb requires avx instruction set). This problem reproduces on 23.04 Lua kernel (6.2.0-20), 22.04 Jammy HWE kernel (5.19.0-35) but not on Jammy GA kernel (5.15.0-71.78). I'm suspecting a kernel regression since v>5.15 that would be more strict with possibly QEMU emulated XSAVE CPUID features. Related yet unanswered support question: https://askubuntu.com/questions/1467238/xsave-consistency-problem- preventing-avx-on-kvm-guests-running-jammy-hwe This looks similar to the following kernel thread https://lore.kernel.org/lkml/a60333b9-6b42-4730-6509-cf1a0cd5c...@citrix.com/T/ Although I don't yet have access to the KVM hypervisor host, I'd like to know if there is a possible workaround by fixing KVM/QEMU configuration possibly enabling XSAVEC in addition to XSAVES feature in the KVM guest, for upgrading KVM/QEMU version. Full diagnostics performed so far at https://github.com/orange- cloudfoundry/paas-templates/issues/1960#issuecomment-1534484042 ProblemType: Bug DistroRelease: Ubuntu 23.04 Package: linux-image-6.2.0-20-generic 6.2.0-20.20 ProcVersionSignature: Ubuntu 6.2.0-20.20-generic 6.2.6 Uname: Linux 6.2.0-20-generic x86_64 AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 May 10 09:35 seq crw-rw---- 1 root audio 116, 33 May 10 09:35 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay' ApportVersion: 2.26.1-0ubuntu2 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CRDA: N/A CasperMD5CheckResult: unknown Date: Wed May 10 12:31:18 2023 IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig' Lspci: Error: [Errno 2] No such file or directory: 'lspci' Lspci-vt: Error: [Errno 2] No such file or directory: 'lspci' Lsusb: Error: [Errno 2] No such file or directory: 'lsusb' Lsusb-t: Error: [Errno 2] No such file or directory: 'lsusb' Lsusb-v: Error: [Errno 2] No such file or directory: 'lsusb' MachineType: OpenStack Foundation OpenStack Nova PciMultimedia: ProcFB: 0 cirrusdrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.2.0-20-generic root=UUID=03a4e7a1-715a-4ceb-8fa6-d86a817a7092 ro vconsole.keymap=us net.ifnames=0 biosdevname=0 crashkernel=auto selinux=0 plymouth.enable=0 console=ttyS0,115200n8 earlyprintk=ttyS0 rootdelay=300 ipv6.disable=1 audit=1 cgroup_enable=memory swapaccount=1 systemd.unified_cgroup_hierarchy=false quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-6.2.0-20-generic N/A linux-backports-modules-6.2.0-20-generic N/A linux-firmware 20230323.gitbcdcfbcf-0ubuntu1 RfKill: Error: [Errno 2] No such file or directory: 'rfkill' SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 04/01/2014 dmi.bios.release: 0.0 dmi.bios.vendor: SeaBIOS dmi.bios.version: rel-1.10.2-0-g5f4c7b1-20181220_000000-szxrtosci10000 dmi.chassis.type: 1 dmi.chassis.vendor: QEMU dmi.chassis.version: pc-i440fx-2.8 dmi.modalias: dmi:bvnSeaBIOS:bvrrel-1.10.2-0-g5f4c7b1-20181220_000000-szxrtosci10000:bd04/01/2014:br0.0:svnOpenStackFoundation:pnOpenStackNova:pvr13.2.1-20220808115737_bd245dd:cvnQEMU:ct1:cvrpc-i440fx-2.8:sku: dmi.product.family: Virtual Machine dmi.product.name: OpenStack Nova dmi.product.version: 13.2.1-20220808115737_bd245dd dmi.sys.vendor: OpenStack Foundation To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2019108/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
