[PATCH 4.10 02/81] KVM: nVMX: fix nested EPT detection

Greg Kroah-Hartman
2017-04-06T09:05:54Z

From: Ladi Prosek <lprosek@redhat.com>

commit 7ad658b693536741c37b16aeb07840a2ce75f5b9 upstream.

The nested_ept_enabled flag introduced in commit 7ca29de2136 was not
computed correctly. We are interested only in L1's EPT state, not the
the combined L0+L1 value.

In particular, if L0 uses EPT but L1 does not, nested_ept_enabled must
be false to make sure that PDPSTRs are loaded based on CR3 as usual,
because the special case described in 26.3.2.4 Loading Page-Directory-
Pointer-Table Entries does not apply.

Fixes: 7ca29de21362 ("KVM: nVMX: fix CR3 load if L2 uses PAE paging and EPT")
Cc: qemu-stable@nongnu.org
Reported-by: Wanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/vmx.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10027,7 +10027,6 @@ static int prepare_vmcs02(struct kvm_vcp
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 exec_control;
- bool nested_ept_enabled = false;

vmcs_write16(GUEST_ES_SELECTOR, vmcs12->guest_es_selector);
vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector);
@@ -10192,7 +10191,6 @@ static int prepare_vmcs02(struct kvm_vcp
vmcs12->guest_intr_status);
}

- nested_ept_enabled = (exec_control & SECONDARY_EXEC_ENABLE_EPT) != 0;
vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
}

@@ -10344,7 +10342,7 @@ static int prepare_vmcs02(struct kvm_vcp
vmx_set_efer(vcpu, vcpu->arch.efer);

/* Shadow page tables on either EPT or shadow page tables. */
- if (nested_vmx_load_cr3(vcpu, vmcs12->guest_cr3, nested_ept_enabled,
+ if (nested_vmx_load_cr3(vcpu, vmcs12->guest_cr3, nested_cpu_has_ept(vmcs12),
entry_failure_code))
return 1;