linux-kernel - [PATCH v4 6/9] KVM: nSVM: move kvm_set_cr3() after nested_svm_uninit_mmu

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Date:   Fri, 10 Jul 2020 16:11:54 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 6/9] KVM: nSVM: move kvm_set_cr3() after nested_svm_uninit_mmu_context()

kvm_mmu_new_pgd() refers to arch.mmu and at this point it still references
arch.guest_mmu while arch.root_mmu is expected.

Note, the change is effectively a nop: when !npt_enabled,
nested_svm_uninit_mmu_context() does nothing (as we don't do
nested_svm_init_mmu_context()) and with npt_enabled we don't
do kvm_set_cr3() but we're about to switch to nested_svm_load_cr3().

No functional change intended.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/svm/nested.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 180929f3dbef..2c308dfa5468 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -611,12 +611,6 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	svm_set_efer(&svm->vcpu, hsave->save.efer);
 	svm_set_cr0(&svm->vcpu, hsave->save.cr0 | X86_CR0_PE);
 	svm_set_cr4(&svm->vcpu, hsave->save.cr4);
-	if (npt_enabled) {
-		svm->vmcb->save.cr3 = hsave->save.cr3;
-		svm->vcpu.arch.cr3 = hsave->save.cr3;
-	} else {
-		(void)kvm_set_cr3(&svm->vcpu, hsave->save.cr3);
-	}
 	kvm_rax_write(&svm->vcpu, hsave->save.rax);
 	kvm_rsp_write(&svm->vcpu, hsave->save.rsp);
 	kvm_rip_write(&svm->vcpu, hsave->save.rip);
@@ -636,6 +630,14 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	kvm_vcpu_unmap(&svm->vcpu, &map, true);
 
 	nested_svm_uninit_mmu_context(&svm->vcpu);
+
+	if (npt_enabled) {
+		svm->vmcb->save.cr3 = hsave->save.cr3;
+		svm->vcpu.arch.cr3 = hsave->save.cr3;
+	} else {
+		(void)kvm_set_cr3(&svm->vcpu, hsave->save.cr3);
+	}
+
 	kvm_mmu_reset_context(&svm->vcpu);
 	kvm_mmu_load(&svm->vcpu);
 
-- 
2.25.4