linux-kernel - [PATCH v2 03/46] KVM: SVM: Zero out GDTR.base and IDTR.base on INIT

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Date:   Tue, 13 Jul 2021 09:32:41 -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, Reiji Watanabe <reijiw@...gle.com>
Subject: [PATCH v2 03/46] KVM: SVM: Zero out GDTR.base and IDTR.base on INIT

Explicitly set GDTR.base and IDTR.base to zero when intializing the VMCB.
Functionally this only affects INIT, as the bases are implicitly set to
zero on RESET by virtue of the VMCB being zero allocated.

Per AMD's APM, GDTR.base and IDTR.base are zeroed after RESET and INIT.

Fixes: 04d2cc7780d4 ("KVM: Move main vcpu loop into subarch independent code")
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 616b9679ddcc..2150642e1bef 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1254,7 +1254,9 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
 		SVM_SELECTOR_S_MASK | SVM_SELECTOR_CODE_MASK;
 	save->cs.limit = 0xffff;
 
+	save->gdtr.base = 0;
 	save->gdtr.limit = 0xffff;
+	save->idtr.base = 0;
 	save->idtr.limit = 0xffff;
 
 	init_sys_seg(&save->ldtr, SEG_TYPE_LDT);
-- 
2.32.0.93.g670b81a890-goog