KVM: nVMX: load GUEST_EFER after GUEST_CR0 during emulated VM-entry

vmx_set_cr0() modifies GUEST_EFER and "IA-32e mode guest" in the current
VMCS. Call vmx_set_efer() after vmx_set_cr0() so that emulated VM-entry
is more faithful to VMCS12.

This patch correctly causes VM-entry to fail when "IA-32e mode guest" is
1 and GUEST_CR0.PG is 0. Previously this configuration would succeed and
"IA-32e mode guest" would silently be disabled by KVM.

Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fa29585..d1a4f42 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10272,15 +10272,6 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
                nested_ept_init_mmu_context(vcpu);
        }
 
-       if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER)
-               vcpu->arch.efer = vmcs12->guest_ia32_efer;
-       else if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
-               vcpu->arch.efer |= (EFER_LMA | EFER_LME);
-       else
-               vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
-       /* Note: modifies VM_ENTRY/EXIT_CONTROLS and GUEST/HOST_IA32_EFER */
-       vmx_set_efer(vcpu, vcpu->arch.efer);
-
        /*
         * This sets GUEST_CR0 to vmcs12->guest_cr0, with possibly a modified
         * TS bit (for lazy fpu) and bits which we consider mandatory enabled.
@@ -10295,6 +10286,15 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
        vmx_set_cr4(vcpu, vmcs12->guest_cr4);
        vmcs_writel(CR4_READ_SHADOW, nested_read_cr4(vmcs12));
 
+       if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER)
+               vcpu->arch.efer = vmcs12->guest_ia32_efer;
+       else if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
+               vcpu->arch.efer |= (EFER_LMA | EFER_LME);
+       else
+               vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
+       /* Note: modifies VM_ENTRY/EXIT_CONTROLS and GUEST/HOST_IA32_EFER */
+       vmx_set_efer(vcpu, vcpu->arch.efer);
+
        /* shadow page tables on either EPT or shadow page tables */
        kvm_set_cr3(vcpu, vmcs12->guest_cr3);
        kvm_mmu_reset_context(vcpu);