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

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Date:   Thu,  6 Apr 2017 10:37:54 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, qemu-stable@...gnu.org,
        Wanpeng Li <wanpeng.li@...mail.com>,
        David Hildenbrand <david@...hat.com>,
        Ladi Prosek <lprosek@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 4.10 02/81] KVM: nVMX: fix nested EPT detection

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ladi Prosek <lprosek@...hat.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@...gnu.org
Reported-by: Wanpeng Li <wanpeng.li@...mail.com>
Reviewed-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Ladi Prosek <lprosek@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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;