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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2022-04-07 22:10:13 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-04-11 13:29:51 -0400 |
| commit | 42dcbe7d8bac997eef4c379e61d9121a15ed4e36 (patch) | |
| tree | 8ae299a7eb6ccd0bcd75c1ddf079cba88d1e5109 /arch/x86/include/asm/kvm_host.h | |
| parent | c538dc792ff7e456d777f585fdf96aa4e781ed66 (diff) | |
| download | lwn-42dcbe7d8bac997eef4c379e61d9121a15ed4e36.tar.gz lwn-42dcbe7d8bac997eef4c379e61d9121a15ed4e36.zip | |
KVM: x86: hyper-v: Avoid writing to TSC page without an active vCPU
The following WARN is triggered from kvm_vm_ioctl_set_clock():
WARNING: CPU: 10 PID: 579353 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:3161 mark_page_dirty_in_slot+0x6c/0x80 [kvm]
...
CPU: 10 PID: 579353 Comm: qemu-system-x86 Tainted: G W O 5.16.0.stable #20
Hardware name: LENOVO 20UF001CUS/20UF001CUS, BIOS R1CET65W(1.34 ) 06/17/2021
RIP: 0010:mark_page_dirty_in_slot+0x6c/0x80 [kvm]
...
Call Trace:
<TASK>
? kvm_write_guest+0x114/0x120 [kvm]
kvm_hv_invalidate_tsc_page+0x9e/0xf0 [kvm]
kvm_arch_vm_ioctl+0xa26/0xc50 [kvm]
? schedule+0x4e/0xc0
? __cond_resched+0x1a/0x50
? futex_wait+0x166/0x250
? __send_signal+0x1f1/0x3d0
kvm_vm_ioctl+0x747/0xda0 [kvm]
...
The WARN was introduced by commit 03c0304a86bc ("KVM: Warn if
mark_page_dirty() is called without an active vCPU") but the change seems
to be correct (unlike Hyper-V TSC page update mechanism). In fact, there's
no real need to actually write to guest memory to invalidate TSC page, this
can be done by the first vCPU which goes through kvm_guest_time_update().
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220407201013.963226-1-vkuznets@redhat.com>
Diffstat (limited to 'arch/x86/include/asm/kvm_host.h')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 92843fcdc1cf..e0c0f0e1f754 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -974,12 +974,10 @@ enum hv_tsc_page_status { HV_TSC_PAGE_UNSET = 0, /* TSC page MSR was written by the guest, update pending */ HV_TSC_PAGE_GUEST_CHANGED, - /* TSC page MSR was written by KVM userspace, update pending */ + /* TSC page update was triggered from the host side */ HV_TSC_PAGE_HOST_CHANGED, /* TSC page was properly set up and is currently active */ HV_TSC_PAGE_SET, - /* TSC page is currently being updated and therefore is inactive */ - HV_TSC_PAGE_UPDATING, /* TSC page was set up with an inaccessible GPA */ HV_TSC_PAGE_BROKEN, }; |