KVM: VMX: Avoid saving and restoring msr_efer on lightweight vmexit

[mirror_ubuntu-artful-kernel.git] / drivers / kvm / kvm_main.c

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 095d673b9efb8d6ee2026f81456619c821401b68..af07cd539bbac481af799d8108352924c75b8647 100644 (file)
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -73,6 +73,7 @@ static struct kvm_stats_debugfs_item {
        { "request_irq", STAT_OFFSET(request_irq_exits) },
        { "irq_exits", STAT_OFFSET(irq_exits) },
        { "light_exits", STAT_OFFSET(light_exits) },
+       { "efer_reload", STAT_OFFSET(efer_reload) },
        { NULL }
 };
 
@@ -2378,6 +2379,27 @@ out:
        return r;
 }
 
+static void cpuid_fix_nx_cap(struct kvm_vcpu *vcpu)
+{
+       u64 efer;
+       int i;
+       struct kvm_cpuid_entry *e, *entry;
+
+       rdmsrl(MSR_EFER, efer);
+       entry = NULL;
+       for (i = 0; i < vcpu->cpuid_nent; ++i) {
+               e = &vcpu->cpuid_entries[i];
+               if (e->function == 0x80000001) {
+                       entry = e;
+                       break;
+               }
+       }
+       if (entry && (entry->edx & EFER_NX) && !(efer & EFER_NX)) {
+               entry->edx &= ~(1 << 20);
+               printk(KERN_INFO ": guest NX capability removed\n");
+       }
+}
+
 static int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
                                    struct kvm_cpuid *cpuid,
                                    struct kvm_cpuid_entry __user *entries)
@@ -2392,6 +2414,7 @@ static int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
                           cpuid->nent * sizeof(struct kvm_cpuid_entry)))
                goto out;
        vcpu->cpuid_nent = cpuid->nent;
+       cpuid_fix_nx_cap(vcpu);
        return 0;
 
 out: