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authorVitaly Kuznetsov <vkuznets@redhat.com>2022-04-07 22:10:13 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2022-04-11 19:29:51 +0200
commit42dcbe7d8bac997eef4c379e61d9121a15ed4e36 (patch)
tree8ae299a7eb6ccd0bcd75c1ddf079cba88d1e5109 /arch/x86/kvm/x86.c
parentKVM: SVM: Do not activate AVIC for SEV-enabled guest (diff)
downloadlinux-42dcbe7d8bac997eef4c379e61d9121a15ed4e36.tar.xz
linux-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 '')
-rw-r--r--arch/x86/kvm/x86.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index de49a88df1c2..547ba00ef64f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2901,7 +2901,7 @@ static void kvm_end_pvclock_update(struct kvm *kvm)
static void kvm_update_masterclock(struct kvm *kvm)
{
- kvm_hv_invalidate_tsc_page(kvm);
+ kvm_hv_request_tsc_page_update(kvm);
kvm_start_pvclock_update(kvm);
pvclock_update_vm_gtod_copy(kvm);
kvm_end_pvclock_update(kvm);
@@ -3113,8 +3113,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
offsetof(struct compat_vcpu_info, time));
if (vcpu->xen.vcpu_time_info_set)
kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_time_info_cache, 0);
- if (!v->vcpu_idx)
- kvm_hv_setup_tsc_page(v->kvm, &vcpu->hv_clock);
+ kvm_hv_setup_tsc_page(v->kvm, &vcpu->hv_clock);
return 0;
}
@@ -6241,7 +6240,7 @@ static int kvm_vm_ioctl_set_clock(struct kvm *kvm, void __user *argp)
if (data.flags & ~KVM_CLOCK_VALID_FLAGS)
return -EINVAL;
- kvm_hv_invalidate_tsc_page(kvm);
+ kvm_hv_request_tsc_page_update(kvm);
kvm_start_pvclock_update(kvm);
pvclock_update_vm_gtod_copy(kvm);