From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
commit 88dddc11a8d6b09201b4db9d255b3394d9bc9e57 upstream.
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@xxxxxxxxxxx>
Cc: Liran Alon <liran.alon@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7694,6 +7694,7 @@ static void vmx_disable_shadow_vmcs(stru
{
vmcs_clear_bits(SECONDARY_VM_EXEC_CONTROL, SECONDARY_EXEC_SHADOW_VMCS);
vmcs_write64(VMCS_LINK_POINTER, -1ull);
+ vmx->nested.sync_shadow_vmcs = false;
}
static inline void nested_release_vmcs12(struct vcpu_vmx *vmx)
@@ -7705,7 +7706,6 @@ static inline void nested_release_vmcs12
/* copy to memory all shadowed fields in case
they were modified */
copy_shadow_to_vmcs12(vmx);
- vmx->nested.sync_shadow_vmcs = false;
vmx_disable_shadow_vmcs(vmx);
}
vmx->nested.posted_intr_nv = -1;
@@ -7891,6 +7891,9 @@ static void copy_shadow_to_vmcs12(struct
const unsigned long *fields = shadow_read_write_fields;
const int num_fields = max_shadow_read_write_fields;
+ if (WARN_ON(!shadow_vmcs))
+ return;
+
preempt_disable();
vmcs_load(shadow_vmcs);
@@ -7938,6 +7941,9 @@ static void copy_vmcs12_to_shadow(struct
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++) {
