diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2020-06-22 16:37:42 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-06-22 13:37:30 -0400 |
| commit | 44d527170731c75587e95052f3eea72b8c651daf (patch) | |
| tree | b982f99840d0e5b36f01e730d8d7ad5c8227c067 /arch/x86/include | |
| parent | af28dfacbe00d53df5dec2bf50640df33138b1fe (diff) | |
KVM: LAPIC: ensure APIC map is up to date on concurrent update requests
The following race can cause lost map update events:
cpu1 cpu2
apic_map_dirty = true
------------------------------------------------------------
kvm_recalculate_apic_map:
pass check
mutex_lock(&kvm->arch.apic_map_lock);
if (!kvm->arch.apic_map_dirty)
and in process of updating map
-------------------------------------------------------------
other calls to
apic_map_dirty = true might be too late for affected cpu
-------------------------------------------------------------
apic_map_dirty = false
-------------------------------------------------------------
kvm_recalculate_apic_map:
bail out on
if (!kvm->arch.apic_map_dirty)
To fix it, record the beginning of an update of the APIC map in
apic_map_dirty. If another APIC map change switches apic_map_dirty
back to DIRTY during the update, kvm_recalculate_apic_map should not
make it CLEAN, and the other caller will go through the slow path.
Reported-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index f8998e97457f..f852ee350beb 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -943,7 +943,7 @@ struct kvm_arch { atomic_t vapics_in_nmi_mode; struct mutex apic_map_lock; struct kvm_apic_map *apic_map; - bool apic_map_dirty; + atomic_t apic_map_dirty; bool apic_access_page_done; unsigned long apicv_inhibit_reasons; |