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authorPaolo Bonzini <pbonzini@redhat.com>2020-06-22 16:37:42 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2020-06-22 13:37:30 -0400
commit44d527170731c75587e95052f3eea72b8c651daf (patch)
treeb982f99840d0e5b36f01e730d8d7ad5c8227c067 /arch/x86/include
parentaf28dfacbe00d53df5dec2bf50640df33138b1fe (diff)
downloadlinux-44d527170731c75587e95052f3eea72b8c651daf.tar.gz
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.h2
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;