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Commit 967bc679 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Greg Kroah-Hartman
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KVM: nVMX: do not use dangling shadow VMCS after guest reset 



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: default avatarJan Kiszka <jan.kiszka@siemens.com>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3a17ca86

arch/x86/kvm/vmx.c

+7 −1
Original line number Diff line number Diff line
@@ -8457,6 +8457,7 @@ 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.sync_shadow_vmcs = false;

}



static inline void nested_release_vmcs12(struct vcpu_vmx *vmx)
@@ -8468,7 +8469,6 @@ static inline void nested_release_vmcs12(struct vcpu_vmx *vmx) 
		/* 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;
@@ -8668,6 +8668,9 @@ 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);
@@ -8706,6 +8709,9 @@ 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++) {