linux-kernel - [PATCH 08/23] KVM: nSVM: only copy L1 non-VMLOAD/VMSAVE data in svm_set_nested

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Date:   Tue,  2 Mar 2021 14:33:28 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     seanjc@...gle.com
Subject: [PATCH 08/23] KVM: nSVM: only copy L1 non-VMLOAD/VMSAVE data in svm_set_nested_state()

The VMLOAD/VMSAVE data is not taken from userspace, since it will
not be restored on VMEXIT (it will be copied from VMCB02 to VMCB01).
For clarity, replace the wholesale copy of the VMCB save area
with a copy of that state only.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/svm/nested.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 945c2a48b591..585b5aa1914f 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -715,7 +715,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	/*
 	 * Restore processor state that had been saved in vmcb01
 	 */
-	kvm_set_rflags(&svm->vcpu, svm->vmcb->save.rflags | X86_EFLAGS_FIXED);
+	kvm_set_rflags(&svm->vcpu, svm->vmcb->save.rflags);
 	svm_set_efer(&svm->vcpu, svm->vmcb->save.efer);
 	svm_set_cr0(&svm->vcpu, svm->vmcb->save.cr0 | X86_CR0_PE);
 	svm_set_cr4(&svm->vcpu, svm->vmcb->save.cr4);
@@ -1250,7 +1250,23 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 	svm->nested.vmcb12_gpa = kvm_state->hdr.svm.vmcb_pa;
 	if (svm->current_vmcb == &svm->vmcb01)
 		svm->nested.vmcb02.ptr->save = svm->vmcb01.ptr->save;
-	svm->vmcb01.ptr->save = *save;
+
+	svm->vmcb01.ptr->save.es = save->es;
+	svm->vmcb01.ptr->save.cs = save->cs;
+	svm->vmcb01.ptr->save.ss = save->ss;
+	svm->vmcb01.ptr->save.ds = save->ds;
+	svm->vmcb01.ptr->save.gdtr = save->gdtr;
+	svm->vmcb01.ptr->save.idtr = save->idtr;
+	svm->vmcb01.ptr->save.rflags = save->rflags | X86_EFLAGS_FIXED;
+	svm->vmcb01.ptr->save.efer = save->efer;
+	svm->vmcb01.ptr->save.cr0 = save->cr0;
+	svm->vmcb01.ptr->save.cr3 = save->cr3;
+	svm->vmcb01.ptr->save.cr4 = save->cr4;
+	svm->vmcb01.ptr->save.rax = save->rax;
+	svm->vmcb01.ptr->save.rsp = save->rsp;
+	svm->vmcb01.ptr->save.rip = save->rip;
+	svm->vmcb01.ptr->save.cpl = 0;
+
 	nested_load_control_from_vmcb12(svm, ctl);
 
 	svm_switch_vmcb(svm, &svm->nested.vmcb02);
-- 
2.26.2