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Date: Wed, 18 Apr 2012 15:03:04 +0300 From: Avi Kivity <avi@...hat.com> To: kvm@...r.kernel.org, Marcelo Tosatti <mtosatti@...hat.com> Cc: linux-kernel@...r.kernel.org, davej@...hat.com Subject: [PATCH 3.4-rc] KVM: VMX: Fix kvm_set_shared_msr() called in preemptible context 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@...hat.com> Signed-off-by: Avi Kivity <avi@...hat.com> --- arch/x86/kvm/vmx.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index ad85adf..4ff0ab9 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2210,9 +2210,12 @@ 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, msr->mask); + preempt_enable(); + } break; } ret = kvm_set_msr_common(vcpu, msr_index, data); -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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