From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Liran Alon <liran.alon@oracle.com>, stable@vger.kernel.org
Subject: [PATCH v2] KVM: nVMX: do not use dangling shadow VMCS after guest reset
Date: Fri, 19 Jul 2019 23:39:50 +0200 [thread overview]
Message-ID: <1563572390-28823-1-git-send-email-pbonzini@redhat.com> (raw)
If a KVM guest is reset while running a nested guest, free_nested will
disable the shadow VMCS execution control in the vmcs01. However,
on the next KVM_RUN vmx_vcpu_run would nevertheless try to sync
the VMCS12 to the shadow VMCS which has since been freed.
This causes a vmptrld of a NULL pointer on my machime, but Jan reports
the host to hang altogether. Let's see how much this trivial patch fixes.
Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx/nested.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 4f23e34f628b..0f1378789bd0 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -194,6 +194,7 @@ static void vmx_disable_shadow_vmcs(struct vcpu_vmx *vmx)
{
secondary_exec_controls_clearbit(vmx, SECONDARY_EXEC_SHADOW_VMCS);
vmcs_write64(VMCS_LINK_POINTER, -1ull);
+ vmx->nested.need_vmcs12_to_shadow_sync = false;
}
static inline void nested_release_evmcs(struct kvm_vcpu *vcpu)
@@ -1341,6 +1342,9 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
unsigned long val;
int i;
+ if (WARN_ON(!shadow_vmcs))
+ return;
+
preempt_disable();
vmcs_load(shadow_vmcs);
@@ -1373,6 +1377,9 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
unsigned long val;
int i, q;
+ if (WARN_ON(!shadow_vmcs))
+ return;
+
vmcs_load(shadow_vmcs);
for (q = 0; q < ARRAY_SIZE(fields); q++) {
@@ -4436,7 +4443,6 @@ static inline void nested_release_vmcs12(struct kvm_vcpu *vcpu)
/* copy to memory all shadowed fields in case
they were modified */
copy_shadow_to_vmcs12(vmx);
- vmx->nested.need_vmcs12_to_shadow_sync = false;
vmx_disable_shadow_vmcs(vmx);
}
vmx->nested.posted_intr_nv = -1;
--
1.8.3.1
next reply other threads:[~2019-07-19 21:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-19 21:39 Paolo Bonzini [this message]
2019-07-19 22:06 ` [PATCH v2] KVM: nVMX: do not use dangling shadow VMCS after guest reset Liran Alon
2019-07-19 22:21 ` Paolo Bonzini
2019-07-19 22:23 ` Liran Alon
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