KVM: VMX: Pass cr0.mp through to the guest when the fpu is active
When cr0.mp is clear, the guest doesn't expect a #NM in response to
a WAIT instruction. Because we always keep cr0.mp set, it will get
a #NM, and potentially be confused.
Fix by keeping cr0.mp set only when the fpu is inactive, and passing
it through when inactive.
Reported-by: Lorenzo Martignoni <martignlo@gmail.com>
Analyzed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a680d93..7a56879 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -66,7 +66,7 @@
#define KVM_GUEST_CR0_MASK \
(KVM_GUEST_CR0_MASK_UNRESTRICTED_GUEST | X86_CR0_PG | X86_CR0_PE)
#define KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST \
- (X86_CR0_WP | X86_CR0_NE | X86_CR0_MP)
+ (X86_CR0_WP | X86_CR0_NE)
#define KVM_VM_CR0_ALWAYS_ON \
(KVM_VM_CR0_ALWAYS_ON_UNRESTRICTED_GUEST | X86_CR0_PG | X86_CR0_PE)
#define KVM_CR4_GUEST_OWNED_BITS \
@@ -791,12 +791,15 @@
static void vmx_fpu_activate(struct kvm_vcpu *vcpu)
{
+ ulong cr0;
+
if (vcpu->fpu_active)
return;
vcpu->fpu_active = 1;
- vmcs_clear_bits(GUEST_CR0, X86_CR0_TS);
- if (kvm_read_cr0_bits(vcpu, X86_CR0_TS))
- vmcs_set_bits(GUEST_CR0, X86_CR0_TS);
+ cr0 = vmcs_readl(GUEST_CR0);
+ cr0 &= ~(X86_CR0_TS | X86_CR0_MP);
+ cr0 |= kvm_read_cr0_bits(vcpu, X86_CR0_TS | X86_CR0_MP);
+ vmcs_writel(GUEST_CR0, cr0);
update_exception_bitmap(vcpu);
vcpu->arch.cr0_guest_owned_bits = X86_CR0_TS;
vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);
@@ -807,7 +810,7 @@
static void vmx_fpu_deactivate(struct kvm_vcpu *vcpu)
{
vmx_decache_cr0_guest_bits(vcpu);
- vmcs_set_bits(GUEST_CR0, X86_CR0_TS);
+ vmcs_set_bits(GUEST_CR0, X86_CR0_TS | X86_CR0_MP);
update_exception_bitmap(vcpu);
vcpu->arch.cr0_guest_owned_bits = 0;
vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);
@@ -1757,7 +1760,7 @@
ept_update_paging_mode_cr0(&hw_cr0, cr0, vcpu);
if (!vcpu->fpu_active)
- hw_cr0 |= X86_CR0_TS;
+ hw_cr0 |= X86_CR0_TS | X86_CR0_MP;
vmcs_writel(CR0_READ_SHADOW, cr0);
vmcs_writel(GUEST_CR0, hw_cr0);