[PATCH] KVM: x86: Fix the #GP(0) and #UD conditions for XSETBV emulation

From: Like Xu <like.xu.linux@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Jim Mattson <jmattson@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] KVM: x86: Fix the #GP(0) and #UD conditions for XSETBV emulation
Date: Mon, 17 Jan 2022 15:24:56 +0800	[thread overview]
Message-ID: <20220117072456.71155-1-likexu@tencent.com> (raw)

From: Like Xu <likexu@tencent.com>

According to Intel SDM "XSETBV—Set Extended Control Register",
the #UD exception is raised if CPUID.01H:ECX.XSAVE[bit 26] = 0
or if CR4.OSXSAVE[bit 18] = 0, and the #GP(0) exception for the
reason "if the current privilege level is not 0" is only valid
in the protected mode. Translate them into KVM terms.

Fixes: 92f9895c146d ("Move XSETBV emulation to common code")
Signed-off-by: Like Xu <likexu@tencent.com>
---
 arch/x86/kvm/x86.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 76b4803dd3bd..7d8622e592bb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1024,7 +1024,11 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 
 int kvm_emulate_xsetbv(struct kvm_vcpu *vcpu)
 {
-	if (static_call(kvm_x86_get_cpl)(vcpu) != 0 ||
+	if (!guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) ||
+	    !kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
+		return kvm_handle_invalid_op(vcpu);
+
+	if ((is_protmode(vcpu) && static_call(kvm_x86_get_cpl)(vcpu) != 0) ||
 	    __kvm_set_xcr(vcpu, kvm_rcx_read(vcpu), kvm_read_edx_eax(vcpu))) {
 		kvm_inject_gp(vcpu, 0);
 		return 1;
-- 
2.33.1

