This is a note to let you know that I've just added the patch titled
KVM: x86: make vapics_in_nmi_mode atomic
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-make-vapics_in_nmi_mode-atomic.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 42720138b06301cc8a7ee8a495a6d021c4b6a9bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@xxxxxxxxxx>
Date: Wed, 1 Jul 2015 15:31:49 +0200
Subject: KVM: x86: make vapics_in_nmi_mode atomic
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From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@xxxxxxxxxx>
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@xxxxxxxxxx>
[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@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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(-)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -571,7 +571,7 @@ 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;
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -305,7 +305,7 @@ static void pit_do_work(struct kthread_w
* 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);
}
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1109,10 +1109,10 @@ static void apic_manage_nmi_watchdog(str
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)
Patches currently in stable-queue which might be from rkrcmar@xxxxxxxxxx are
queue-3.14/kvm-x86-make-vapics_in_nmi_mode-atomic.patch
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