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Message-Id: <1435695558-3168-4-git-send-email-rkrcmar@redhat.com>
Date: Tue, 30 Jun 2015 22:19:18 +0200
From: Radim Krčmář <rkrcmar@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
Yoshida Nobuo <yoshida.nb@...s.nec.co.jp>
Subject: [PATCH 3/3] KVM: x86: make vapics_in_nmi_mode atomic
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@...hat.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/i8254.c | 2 +-
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 c7fa57b529d2..2a7f5d782c33 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -607,7 +607,7 @@ 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;
struct mutex apic_map_lock;
struct kvm_apic_map *apic_map;
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4dce6f8b6129..f90952f64e79 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -305,7 +305,7 @@ static void pit_do_work(struct kthread_work *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 8dc32b5a4e0d..954e98a8c2e3 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1264,9 +1264,9 @@ static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val)
if (lvt0_in_nmi_mode) {
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
- apic->vcpu->kvm->arch.vapics_in_nmi_mode--;
+ atomic_dec(&apic->vcpu->kvm->arch.vapics_in_nmi_mode);
}
}
--
2.4.5
--
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