linux-kernel - [PATCH 1/4] KVM: VMX: Use current VMCS to query WAITPKG support for MSR emulation

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Message-Id: <20210810171952.2758100-2-seanjc@google.com>
Date:   Tue, 10 Aug 2021 10:19:49 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Zeng Guang <guang.zeng@...el.com>
Subject: [PATCH 1/4] KVM: VMX: Use current VMCS to query WAITPKG support for
 MSR emulation

Use the secondary_exec_controls_get() accessor in vmx_has_waitpkg() to
effectively get the controls for the current VMCS, as opposed to using
vmx->secondary_exec_controls, which is the cached value of KVM's desired
controls for vmcs01 and truly not reflective of any particular VMCS.

While the waitpkg control is not dynamic, i.e. vmcs01 will always hold
the same waitpkg configuration as vmx->secondary_exec_controls, the same
does not hold true for vmcs02 if the L1 VMM hides the feature from L2.
If L1 hides the feature _and_ does not intercept MSR_IA32_UMWAIT_CONTROL,
L2 could incorrectly read/write L1's virtual MSR instead of taking a #GP.

Fixes: 6e3ba4abcea5 ("KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL")
Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/vmx.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 0ecc41189292..4f151175d45a 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -521,7 +521,7 @@ static inline struct vmcs *alloc_vmcs(bool shadow)

 static inline bool vmx_has_waitpkg(struct vcpu_vmx *vmx)
 {
-	return vmx->secondary_exec_control &
+	return secondary_exec_controls_get(vmx) &
 		SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE;
 }

-- 
2.32.0.605.g8dce9f2422-goog