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authorAvi Kivity <avi@redhat.com>2012-05-09 16:10:46 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-12 09:32:20 -0700
commita4dfde33d7f8448d65d066392ecccbbf50d55fd8 (patch)
parent8a4a30bf172a05f53714f0f54af2e044a6ede7a8 (diff)
KVM: VMX: Fix kvm_set_shared_msr() called in preemptible context
(cherry picked from commit 2225fd56049643c1a7d645c0ce9d499d43c7974e) kvm_set_shared_msr() may not be called in preemptible context, but vmx_set_msr() does so: BUG: using smp_processor_id() in preemptible [00000000] code: qemu-kvm/22713 caller is kvm_set_shared_msr+0x32/0xa0 [kvm] Pid: 22713, comm: qemu-kvm Not tainted 3.4.0-rc3+ #39 Call Trace: [<ffffffff8131fa82>] debug_smp_processor_id+0xe2/0x100 [<ffffffffa0328ae2>] kvm_set_shared_msr+0x32/0xa0 [kvm] [<ffffffffa03a103b>] vmx_set_msr+0x28b/0x2d0 [kvm_intel] ... Making kvm_set_shared_msr() work in preemptible is cleaner, but it's used in the fast path. Making two variants is overkill, so this patch just disables preemption around the call. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7f33e337b152..a7a6f6011002 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2219,9 +2219,12 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
msr = find_msr_entry(vmx, msr_index);
if (msr) {
msr->data = data;
- if (msr - vmx->guest_msrs < vmx->save_nmsrs)
+ if (msr - vmx->guest_msrs < vmx->save_nmsrs) {
+ preempt_disable();
kvm_set_shared_msr(msr->index, msr->data,
+ preempt_enable();
+ }
ret = kvm_set_msr_common(vcpu, msr_index, data);