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

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Date:   Mon, 17 Jan 2022 15:24:56 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: x86: Fix the #GP(0) and #UD conditions for XSETBV emulation

From: Like Xu <likexu@...cent.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@...cent.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