linux-kernel - [PATCH 2/5] KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap support for real

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Date:   Mon, 20 Dec 2021 16:21:36 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap support for real

Commit c4327f15dfc7 ("KVM: SVM: hyper-v: Enlightened MSR-Bitmap support")
introduced enlightened MSR-Bitmap support for KVM-on-Hyper-V but it didn't
actually enable the support. Similar to enlightened NPT TLB flush and
direct TLB flush features, the guest (KVM) has to tell L0 (Hyper-V) that
it's using the feature by setting the appropriate feature fit in VMCB
control area (sw reserved fields).

Fixes: c4327f15dfc7 ("KVM: SVM: hyper-v: Enlightened MSR-Bitmap support")
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/svm/svm_onhyperv.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/svm_onhyperv.h b/arch/x86/kvm/svm/svm_onhyperv.h
index cdbcfc63d171..489ca56212c6 100644
--- a/arch/x86/kvm/svm/svm_onhyperv.h
+++ b/arch/x86/kvm/svm/svm_onhyperv.h
@@ -46,6 +46,9 @@ static inline void svm_hv_init_vmcb(struct vmcb *vmcb)
 	if (npt_enabled &&
 	    ms_hyperv.nested_features & HV_X64_NESTED_ENLIGHTENED_TLB)
 		hve->hv_enlightenments_control.enlightened_npt_tlb = 1;
+
+	if (ms_hyperv.nested_features & HV_X64_NESTED_MSR_BITMAP)
+		hve->hv_enlightenments_control.msr_bitmap = 1;
 }
 
 static inline void svm_hv_hardware_setup(void)
-- 
2.33.1