pve-kernel/patches/kernel/0010-KVM-nSVM-Advertise-support-for-flush-by-ASID.patch
Fiona Ebner f3ec9c1f62 patches: kernel: switch to using full index for patch files
git will automatically change the length of the index hashes when
formatting a patch depending on what references are present in the
submodule. After pulling in the stable tags today, git wanted to add
a character to all hashes for me. Use --full-index when generating the
patches to avoid such issues in the future.

No functional change intended.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
2024-12-19 19:52:25 +01:00

38 lines
1.6 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Wed, 18 Oct 2023 12:41:04 -0700
Subject: [PATCH] KVM: nSVM: Advertise support for flush-by-ASID
Advertise support for FLUSHBYASID when nested SVM is enabled, as KVM can
always emulate flushing TLB entries for a vmcb12 ASID, e.g. by running L2
with a new, fresh ASID in vmcb02. Some modern hypervisors, e.g. VMWare
Workstation 17, require FLUSHBYASID support and will refuse to run if it's
not present.
Punt on proper support, as "Honor L1's request to flush an ASID on nested
VMRUN" is one of the TODO items in the (incomplete) list of issues that
need to be addressed in order for KVM to NOT do a full TLB flush on every
nested SVM transition (see nested_svm_transition_tlb_flush()).
Reported-by: Stefan Sterz <s.sterz@proxmox.com>
Closes: https://lkml.kernel.org/r/b9915c9c-4cf6-051a-2d91-44cc6380f455%40proxmox.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Stefan Sterz <s.sterz@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/kvm/svm/svm.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 5ab2c92c7331deba414de1077b3ea0eb58920d66..1cd03c985fdc4f72ea774d8d4457400230409430 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5174,6 +5174,7 @@ static __init void svm_set_cpu_caps(void)
if (nested) {
kvm_cpu_cap_set(X86_FEATURE_SVM);
kvm_cpu_cap_set(X86_FEATURE_VMCBCLEAN);
+ kvm_cpu_cap_set(X86_FEATURE_FLUSHBYASID);
/*
* KVM currently flushes TLBs on *every* nested SVM transition,