38 lines
1.6 KiB
Diff
38 lines
1.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Sean Christopherson <seanjc@google.com>
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Date: Wed, 18 Oct 2023 12:41:04 -0700
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Subject: [PATCH] KVM: nSVM: Advertise support for flush-by-ASID
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Advertise support for FLUSHBYASID when nested SVM is enabled, as KVM can
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always emulate flushing TLB entries for a vmcb12 ASID, e.g. by running L2
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with a new, fresh ASID in vmcb02. Some modern hypervisors, e.g. VMWare
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Workstation 17, require FLUSHBYASID support and will refuse to run if it's
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not present.
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Punt on proper support, as "Honor L1's request to flush an ASID on nested
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VMRUN" is one of the TODO items in the (incomplete) list of issues that
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need to be addressed in order for KVM to NOT do a full TLB flush on every
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nested SVM transition (see nested_svm_transition_tlb_flush()).
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Reported-by: Stefan Sterz <s.sterz@proxmox.com>
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Closes: https://lkml.kernel.org/r/b9915c9c-4cf6-051a-2d91-44cc6380f455%40proxmox.com
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Signed-off-by: Sean Christopherson <seanjc@google.com>
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Signed-off-by: Stefan Sterz <s.sterz@proxmox.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kvm/svm/svm.c | 1 +
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1 file changed, 1 insertion(+)
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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 e90b429c84f1..5c7faf7c447f 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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@@ -5085,6 +5085,7 @@ static __init void svm_set_cpu_caps(void)
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if (nested) {
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kvm_cpu_cap_set(X86_FEATURE_SVM);
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kvm_cpu_cap_set(X86_FEATURE_VMCBCLEAN);
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+ kvm_cpu_cap_set(X86_FEATURE_FLUSHBYASID);
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/*
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* KVM currently flushes TLBs on *every* nested SVM transition,
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