From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: stable@vger.kernel.org
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: [PATCH stable-5.1 1/3] KVM: nVMX: do not use dangling shadow VMCS after guest reset
Date: Thu, 25 Jul 2019 13:49:36 +0200 [thread overview]
Message-ID: <20190725114938.3976-2-vkuznets@redhat.com> (raw)
In-Reply-To: <20190725114938.3976-1-vkuznets@redhat.com>
From: Paolo Bonzini <pbonzini@redhat.com>
[ Upstream commit 88dddc11a8d6b09201b4db9d255b3394d9bc9e57 ]
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 4ca834d22169..3f48006a43ec 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -184,6 +184,7 @@ static void vmx_disable_shadow_vmcs(struct vcpu_vmx *vmx)
{
vmcs_clear_bits(SECONDARY_VM_EXEC_CONTROL, SECONDARY_EXEC_SHADOW_VMCS);
vmcs_write64(VMCS_LINK_POINTER, -1ull);
+ vmx->nested.need_vmcs12_sync = false;
}
static inline void nested_release_evmcs(struct kvm_vcpu *vcpu)
@@ -1328,6 +1329,9 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
u64 field_value;
struct vmcs *shadow_vmcs = vmx->vmcs01.shadow_vmcs;
+ if (WARN_ON(!shadow_vmcs))
+ return;
+
preempt_disable();
vmcs_load(shadow_vmcs);
@@ -1366,6 +1370,9 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
u64 field_value = 0;
struct vmcs *shadow_vmcs = vmx->vmcs01.shadow_vmcs;
+ if (WARN_ON(!shadow_vmcs))
+ return;
+
vmcs_load(shadow_vmcs);
for (q = 0; q < ARRAY_SIZE(fields); q++) {
@@ -4340,7 +4347,6 @@ 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_sync = false;
vmx_disable_shadow_vmcs(vmx);
}
vmx->nested.posted_intr_nv = -1;
--
2.20.1
next prev parent reply other threads:[~2019-07-25 11:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 11:49 [PATCH stable-5.1 0/3] KVM: x86: FPU and nested VMX guest reset fixes Vitaly Kuznetsov
2019-07-25 11:49 ` Vitaly Kuznetsov [this message]
2019-07-25 11:49 ` [PATCH stable-5.1 2/3] KVM: nVMX: Clear pending KVM_REQ_GET_VMCS12_PAGES when leaving nested Vitaly Kuznetsov
2019-07-25 11:49 ` [PATCH stable-5.1 3/3] Revert "kvm: x86: Use task structs fpu field for user" Vitaly Kuznetsov
2019-07-25 15:48 ` [PATCH stable-5.1 0/3] KVM: x86: FPU and nested VMX guest reset fixes Paolo Bonzini
2019-07-26 13:49 ` Greg KH
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