2.6.38-stable review patch. If anyone has any objections, please let us know.
------------------ From: Avi Kivity <[email protected]> commit bd3d1ec3d26b61120bb4f60b18ee99aa81839e6b upstream. When we enable an NMI window, we ask for an IRET intercept, since the IRET re-enables NMIs. However, the IRET intercept happens before the instruction executes, while the NMI window architecturally opens afterwards. To compensate for this mismatch, we only open the NMI window in the following exit, assuming that the IRET has by then executed; however, this assumption is not always correct; we may exit due to a host interrupt or page fault, without having executed the instruction. Fix by checking for forward progress by recording and comparing the IRET's rip. This is somewhat of a hack, since an unchaging rip does not mean that no forward progress has been made, but is the simplest fix for now. Signed-off-by: Avi Kivity <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kvm/svm.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -135,6 +135,8 @@ struct vcpu_svm { u32 *msrpm; + ulong nmi_iret_rip; + struct nested_state nested; bool nmi_singlestep; @@ -2653,6 +2655,7 @@ static int iret_interception(struct vcpu ++svm->vcpu.stat.nmi_window_exits; clr_intercept(svm, INTERCEPT_IRET); svm->vcpu.arch.hflags |= HF_IRET_MASK; + svm->nmi_iret_rip = kvm_rip_read(&svm->vcpu); return 1; } @@ -3474,7 +3477,12 @@ static void svm_complete_interrupts(stru svm->int3_injected = 0; - if (svm->vcpu.arch.hflags & HF_IRET_MASK) { + /* + * If we've made progress since setting HF_IRET_MASK, we've + * executed an IRET and can allow NMI injection. + */ + if ((svm->vcpu.arch.hflags & HF_IRET_MASK) + && kvm_rip_read(&svm->vcpu) != svm->nmi_iret_rip) { svm->vcpu.arch.hflags &= ~(HF_NMI_MASK | HF_IRET_MASK); kvm_make_request(KVM_REQ_EVENT, &svm->vcpu); } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
