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Commit 81231c69 authored by Avi Kivity's avatar Avi Kivity Committed by Marcelo Tosatti
Browse files

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: default avatarLorenzo Martignoni <martignlo@gmail.com>
Analyzed-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent da15bf43

arch/x86/kvm/vmx.c

+9 −6
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ module_param(emulate_invalid_guest_state, bool, S_IRUGO); 
#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_vcpu_put(struct kvm_vcpu *vcpu) 


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_decache_cr0_guest_bits(struct kvm_vcpu *vcpu); 
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 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) 
		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);