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| author | Radim Krčmář <rkrcmar@redhat.com> | 2015-07-01 15:31:49 +0200 |
|---|---|---|
| committer | Zefan Li <lizefan@huawei.com> | 2015-10-22 09:20:07 +0800 |
| commit | 08c730489602b6e3092e54180f47a7b3bfc32172 (patch) | |
| tree | 8940b10d3b4fb1b45087452dc3c217868872cc31 | |
| parent | d4ee09b224ce7d0a815aa8a70a9a01b032358393 (diff) | |
| download | lwn-08c730489602b6e3092e54180f47a7b3bfc32172.tar.gz lwn-08c730489602b6e3092e54180f47a7b3bfc32172.zip | |
KVM: x86: make vapics_in_nmi_mode atomic
commit 42720138b06301cc8a7ee8a495a6d021c4b6a9bc upstream.
Writes were a bit racy, but hard to turn into a bug at the same time.
(Particularly because modern Linux doesn't use this feature anymore.)
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[Actually the next patch makes it much, much easier to trigger the race
so I'm including this one for stable@ as well. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/i8254.c | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/lapic.c | 4 |
3 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 4f787579b329..d60facb1a9d4 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -509,7 +509,7 @@ struct kvm_arch { struct kvm_pic *vpic; struct kvm_ioapic *vioapic; struct kvm_pit *vpit; - int vapics_in_nmi_mode; + atomic_t vapics_in_nmi_mode; unsigned int tss_addr; struct page *apic_access_page; diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index db336f9f2c8c..eaad49aa5bed 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -317,7 +317,7 @@ static void pit_do_work(struct work_struct *work) * LVT0 to NMI delivery. Other PIC interrupts are just sent to * VCPU0, and only if its LVT0 is in EXTINT mode. */ - if (kvm->arch.vapics_in_nmi_mode > 0) + if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0) kvm_for_each_vcpu(i, vcpu, kvm) kvm_apic_nmi_wd_deliver(vcpu); } diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 578613da251e..f935b52515bd 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -761,10 +761,10 @@ static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val) if (!nmi_wd_enabled) { apic_debug("Receive NMI setting on APIC_LVT0 " "for cpu %d\n", apic->vcpu->vcpu_id); - apic->vcpu->kvm->arch.vapics_in_nmi_mode++; + atomic_inc(&apic->vcpu->kvm->arch.vapics_in_nmi_mode); } } else if (nmi_wd_enabled) - apic->vcpu->kvm->arch.vapics_in_nmi_mode--; + atomic_dec(&apic->vcpu->kvm->arch.vapics_in_nmi_mode); } static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val) |