2017-03-22 18:09+0100, Ladi Prosek:
> 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.
>
> Reported-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
> Signed-off-by: Ladi Prosek <lprosek@xxxxxxxxxx>
Adding a standardized "Fixes:" tag even if you mention the commit in
text allows simpler automated backports to stable kernels,
Fixes: 7ca29de21362 ("KVM: nVMX: fix CR3 load if L2 uses PAE paging and EPT")
> ---
> arch/x86/kvm/vmx.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 98e82ee..a525c72 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -10105,8 +10105,11 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
> SECONDARY_EXEC_APIC_REGISTER_VIRT);
> if (nested_cpu_has(vmcs12,
> - CPU_BASED_ACTIVATE_SECONDARY_CONTROLS))
> + CPU_BASED_ACTIVATE_SECONDARY_CONTROLS)) {
> exec_control |= vmcs12->secondary_vm_exec_control;
> + nested_ept_enabled = (vmcs12->secondary_vm_exec_control &
> + SECONDARY_EXEC_ENABLE_EPT) != 0;
I'd prefer to get rid of nested_ept_enabled and directly call
'nested_cpu_has_ept(vmcs12)' instead, like the other place in
prepare_vmcs02() that asks whether we have nested ept.
The change looks correct,
Reviewed-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Thanks.
> + }
>
> if (exec_control & SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY) {
> vmcs_write64(EOI_EXIT_BITMAP0,
> @@ -10121,8 +10124,6 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> vmcs12->guest_intr_status);
> }
>
> - nested_ept_enabled = (exec_control & SECONDARY_EXEC_ENABLE_EPT) != 0;
> -
> /*
> * Write an illegal value to APIC_ACCESS_ADDR. Later,
> * nested_get_vmcs12_pages will either fix it up or
> --
> 2.7.4
>
