74 lines
2.2 KiB
Diff
74 lines
2.2 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Tom Lendacky <thomas.lendacky@amd.com>
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Date: Wed, 20 Dec 2017 10:55:47 +0000
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Subject: [PATCH] x86/svm: Set IBPB when running a different VCPU
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5753
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CVE-2017-5715
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Set IBPB (Indirect Branch Prediction Barrier) when the current CPU is
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going to run a VCPU different from what was previously run.
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit 0ba3eaabbb6666ebd344ee80534e58c375a00810)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kvm/svm.c | 16 ++++++++++++++++
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1 file changed, 16 insertions(+)
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diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
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index a1b19e810c49..fade4869856a 100644
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--- a/arch/x86/kvm/svm.c
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+++ b/arch/x86/kvm/svm.c
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@@ -518,6 +518,8 @@ struct svm_cpu_data {
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struct kvm_ldttss_desc *tss_desc;
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struct page *save_area;
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+
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+ struct vmcb *current_vmcb;
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};
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static DEFINE_PER_CPU(struct svm_cpu_data *, svm_data);
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@@ -1685,11 +1687,19 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
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__free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
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kvm_vcpu_uninit(vcpu);
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kmem_cache_free(kvm_vcpu_cache, svm);
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+
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+ /*
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+ * The VMCB could be recycled, causing a false negative in svm_vcpu_load;
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+ * block speculative execution.
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+ */
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+ if (ibpb_inuse)
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+ wrmsrl(MSR_IA32_PRED_CMD, FEATURE_SET_IBPB);
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}
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static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
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{
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struct vcpu_svm *svm = to_svm(vcpu);
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+ struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
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int i;
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if (unlikely(cpu != vcpu->cpu)) {
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@@ -1718,6 +1728,12 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
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if (static_cpu_has(X86_FEATURE_RDTSCP))
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wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
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+ if (sd->current_vmcb != svm->vmcb) {
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+ sd->current_vmcb = svm->vmcb;
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+ if (ibpb_inuse)
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+ wrmsrl(MSR_IA32_PRED_CMD, FEATURE_SET_IBPB);
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+ }
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+
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avic_vcpu_load(vcpu, cpu);
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}
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--
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2.14.2
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