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Subject[PATCH 3/4] KVM: nVMX: WARN if PML emulation helper is invoked outside of nested guest
Date
WARN if vmx_write_pml_buffer() is called outside of guest mode instead
of silently ignoring the condition. The only caller is nested EPT's
ept_update_accessed_dirty_bits(), which should only be reachable when
L2 is active.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/vmx/vmx.c | 45 +++++++++++++++++++++---------------------
1 file changed, 23 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a2e7e106cc8f..adf83047bb21 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7507,33 +7507,34 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu, gpa_t gpa)
struct vcpu_vmx *vmx = to_vmx(vcpu);
gpa_t dst;

- if (is_guest_mode(vcpu)) {
- WARN_ON_ONCE(vmx->nested.pml_full);
+ if (WARN_ON_ONCE(!is_guest_mode(vcpu)))
+ return 0;

- /*
- * Check if PML is enabled for the nested guest.
- * Whether eptp bit 6 is set is already checked
- * as part of A/D emulation.
- */
- vmcs12 = get_vmcs12(vcpu);
- if (!nested_cpu_has_pml(vmcs12))
- return 0;
+ if (WARN_ON_ONCE(vmx->nested.pml_full))
+ return 1;

- if (vmcs12->guest_pml_index >= PML_ENTITY_NUM) {
- vmx->nested.pml_full = true;
- return 1;
- }
+ /*
+ * Check if PML is enabled for the nested guest. Whether eptp bit 6 is
+ * set is already checked as part of A/D emulation.
+ */
+ vmcs12 = get_vmcs12(vcpu);
+ if (!nested_cpu_has_pml(vmcs12))
+ return 0;

- gpa &= ~0xFFFull;
- dst = vmcs12->pml_address + sizeof(u64) * vmcs12->guest_pml_index;
-
- if (kvm_write_guest_page(vcpu->kvm, gpa_to_gfn(dst), &gpa,
- offset_in_page(dst), sizeof(gpa)))
- return 0;
-
- vmcs12->guest_pml_index--;
+ if (vmcs12->guest_pml_index >= PML_ENTITY_NUM) {
+ vmx->nested.pml_full = true;
+ return 1;
}

+ gpa &= ~0xFFFull;
+ dst = vmcs12->pml_address + sizeof(u64) * vmcs12->guest_pml_index;
+
+ if (kvm_write_guest_page(vcpu->kvm, gpa_to_gfn(dst), &gpa,
+ offset_in_page(dst), sizeof(gpa)))
+ return 0;
+
+ vmcs12->guest_pml_index--;
+
return 0;
}

--
2.26.0
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