pve-edge-kernel/patches/kernel/0008-x86-kvm-Be-careful-not-to-clear-KVM_VCPU_FLUSH_TLB-b.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <[email protected]>
Date: Fri, 31 Jan 2020 08:06:40 -0300
Subject: [PATCH] x86/kvm: Be careful not to clear KVM_VCPU_FLUSH_TLB bit

CVE-2019-3016
CVE-2020-3016

kvm_steal_time_set_preempted() may accidentally clear KVM_VCPU_FLUSH_TLB
bit if it is called more than once while VCPU is preempted.

This is part of CVE-2019-3016.

(This bug was also independently discovered by Jim Mattson
<[email protected]>)

Signed-off-by: Boris Ostrovsky <[email protected]>
Reviewed-by: Joao Martins <[email protected]>
Signed-off-by: Thadeu Lima de Souza Cascardo <[email protected]>
Signed-off-by: Thomas Lamprecht <[email protected]>
---
 arch/x86/kvm/x86.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 778b3a899769..92d8e4ebba16 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3393,6 +3393,9 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
 	if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
 		return;
 
+	if (vcpu->arch.st.steal.preempted)
+		return;
+
 	vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
 
 	kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime,