41 lines
1.3 KiB
Diff
41 lines
1.3 KiB
Diff
From 61fe0ac44f8d9714accad28bab0179d85f969b23 Mon Sep 17 00:00:00 2001
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From: Maxim Levitsky <mlevitsk@redhat.com>
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Date: Tue, 25 Oct 2022 15:47:40 +0300
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Subject: [PATCH] KVM: x86: SVM: don't save SVM state to SMRAM when VM is not
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long mode capable
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When the guest CPUID doesn't have support for long mode, 32 bit SMRAM
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layout is used and it has no support for preserving EFER and/or SVM
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state.
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Note that this isn't relevant to running 32 bit guests on VM which is
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long mode capable - such VM can still run 32 bit guests in compatibility
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mode.
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Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
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---
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arch/x86/kvm/svm/svm.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
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index 44d6a2240e9e..9f2e3fe3dcd7 100644
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--- a/arch/x86/kvm/svm/svm.c
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+++ b/arch/x86/kvm/svm/svm.c
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@@ -4446,6 +4446,14 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, union kvm_smram *smram)
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if (!is_guest_mode(vcpu))
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return 0;
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+ /*
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+ * 32-bit SMRAM format doesn't preserve EFER and SVM state. Userspace is
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+ * responsible for ensuring nested SVM and SMIs are mutually exclusive.
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+ */
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+
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+ if (!guest_cpuid_has(vcpu, X86_FEATURE_LM))
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+ return 1;
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+
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smram->smram64.svm_guest_flag = 1;
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smram->smram64.svm_guest_vmcb_gpa = svm->nested.vmcb12_gpa;
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--
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2.38.1
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