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authorMarcelo Tosatti <mtosatti@redhat.com>2013-04-15 23:30:13 -0300
committerGleb Natapov <gleb@redhat.com>2013-05-08 12:47:43 +0300
commit42bdf991f4cad9678ee2b98c5c2e9299a3f986ef (patch)
treeb0b91769efbecf318e968477cb1b7cc68d0defbd
parent5af43c24ca59a448c9312dd4a4a51d27ec3b9a73 (diff)
downloadlinaro-lsk-42bdf991f4cad9678ee2b98c5c2e9299a3f986ef.tar.gz
KVM: x86: fix maintenance of guest/host xcr0 state
Emulation of xcr0 writes zero guest_xcr0_loaded variable so that subsequent VM-entry reloads CPU's xcr0 with guests xcr0 value. However, this is incorrect because guest_xcr0_loaded variable is read to decide whether to reload hosts xcr0. In case the vcpu thread is scheduled out after the guest_xcr0_loaded = 0 assignment, and scheduler decides to preload FPU: switch_to { __switch_to __math_state_restore restore_fpu_checking fpu_restore_checking if (use_xsave()) fpu_xrstor_checking xrstor64 with CPU's xcr0 == guests xcr0 Fix by properly restoring hosts xcr0 during emulation of xcr0 writes. Analyzed-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
-rw-r--r--arch/x86/kvm/x86.c40
1 files changed, 20 insertions, 20 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 05a8b1a2300..094b5d96ab1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -555,6 +555,25 @@ void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw)
}
EXPORT_SYMBOL_GPL(kvm_lmsw);
+static void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu)
+{
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
+ !vcpu->guest_xcr0_loaded) {
+ /* kvm_set_xcr() also depends on this */
+ xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
+ vcpu->guest_xcr0_loaded = 1;
+ }
+}
+
+static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
+{
+ if (vcpu->guest_xcr0_loaded) {
+ if (vcpu->arch.xcr0 != host_xcr0)
+ xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0);
+ vcpu->guest_xcr0_loaded = 0;
+ }
+}
+
int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
{
u64 xcr0;
@@ -571,8 +590,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
return 1;
if (xcr0 & ~host_xcr0)
return 1;
+ kvm_put_guest_xcr0(vcpu);
vcpu->arch.xcr0 = xcr0;
- vcpu->guest_xcr0_loaded = 0;
return 0;
}
@@ -5614,25 +5633,6 @@ static void inject_pending_event(struct kvm_vcpu *vcpu)
}
}
-static void kvm_load_guest_xcr0(struct kvm_vcpu *vcpu)
-{
- if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
- !vcpu->guest_xcr0_loaded) {
- /* kvm_set_xcr() also depends on this */
- xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0);
- vcpu->guest_xcr0_loaded = 1;
- }
-}
-
-static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
-{
- if (vcpu->guest_xcr0_loaded) {
- if (vcpu->arch.xcr0 != host_xcr0)
- xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0);
- vcpu->guest_xcr0_loaded = 0;
- }
-}
-
static void process_nmi(struct kvm_vcpu *vcpu)
{
unsigned limit = 2;