Description of problem: On an old but well-working server (Dual Xeon 5150), a recent f27 kernel update has made qemu/kvm useless on the machine by slowing it to an absolute crawl. Guest OS doesn't seem to matter (observed both with rhel7 and win10), though post-spectre-ness is possibly related. The following type of message is printed endlessly to the console: [ 2913.089185] vmwrite error: reg 401e value 2020 (err 12) [ 2913.096191] CPU: 0 PID: 5854 Comm: CPU 0/KVM Not tainted 4.16.5-200.fc27.x86_64 #1 [ 2913.103323] Hardware name: Dell Inc. PowerEdge 2900/0J7551, BIOS 2.6.1 04/20/2009 [ 2913.110501] Call Trace: [ 2913.117718] dump_stack+0x5c/0x85 [ 2913.124929] vmx_set_cr4+0x1cf/0x200 [kvm_intel] [ 2913.132200] ? vmexit_fill_RSB+0x18/0x30 [kvm_intel] [ 2913.139529] kvm_set_cr4+0x18e/0x2c0 [kvm] [ 2913.146844] handle_cr+0x5a8/0x650 [kvm_intel] [ 2913.154184] vmx_handle_exit+0xaf/0x14c0 [kvm_intel] [ 2913.161530] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] [ 2913.168864] ? vmexit_fill_RSB+0x18/0x30 [kvm_intel] [ 2913.176055] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] [ 2913.183089] ? vmx_vcpu_run+0x367/0x520 [kvm_intel] [ 2913.190064] kvm_arch_vcpu_ioctl_run+0x699/0x16e0 [kvm] [ 2913.197026] ? kvm_vcpu_mmap+0x20/0x20 [kvm] [ 2913.203930] ? kvm_vcpu_ioctl+0x32b/0x5d0 [kvm] [ 2913.210764] kvm_vcpu_ioctl+0x32b/0x5d0 [kvm] [ 2913.217479] ? __switch_to+0x468/0x4c0 [ 2913.224085] do_vfs_ioctl+0xa4/0x620 [ 2913.230587] SyS_ioctl+0x74/0x80 [ 2913.236917] do_syscall_64+0x74/0x180 [ 2913.243269] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 [ 2913.249638] RIP: 0033:0x7f7f471870f7 [ 2913.255987] RSP: 002b:00007f7f3993a878 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 2913.262537] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f7f471870f7 [ 2913.269174] RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 000000000000000f [ 2913.275839] RBP: 0000560505c69e80 R08: 0000560505c84230 R09: 000000000000ffff [ 2913.282542] R10: 0000560508f735a0 R11: 0000000000000246 R12: 00005605077b6cb6 [ 2913.289356] R13: 0000000000000000 R14: 00007f7f5085c000 R15: 00005605077b6c20 I don't much care if spectre/meltdown protection doesn't work well in the guests or the host for that matter. But these messages are bogging the server down by factors of 100. Version-Release number of selected component (if applicable): kernel-4.16.5-200.fc27.x86_64 qemu-kvm-2.10.1-3.fc27.x86_64
Hi Frank, Thanks for the report. This looks like a known issue (you can confirm by testing https://koji.fedoraproject.org/koji/taskinfo?taskID=26538797). There's a patch that's been submitted upstream. It's not made its way into the KVM tree, though. Once I see a KVM maintainer accept it I'll put it in the Fedora stable builds. *** This bug has been marked as a duplicate of bug 1566258 ***