Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:
> Re-add code to mark CR4.UMIP as reserved if UMIP is not supported by the
> host. The UMIP handling was unintentionally dropped during a recent
> refactoring.
>
> Not flagging CR4.UMIP allows the guest to set its CR4.UMIP regardless of
> host support or userspace desires. On CPUs with UMIP support, including
> emulated UMIP, this allows the guest to enable UMIP against the wishes
> of the userspace VMM. On CPUs without any form of UMIP, this results in
> a failed VM-Enter due to invalid guest state.
>
> Fixes: 345599f9a2928 ("KVM: x86: Add macro to ensure reserved cr4 bits checks stay in sync")
This one in only in kvm/next so just in case another force-push is
around the corner I'd suggest we squash this change in :-)
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 7e3f1d937224..e70d1215638a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -898,6 +898,8 @@ EXPORT_SYMBOL_GPL(kvm_set_xcr);
> __reserved_bits |= X86_CR4_PKE; \
> if (!__cpu_has(__c, X86_FEATURE_LA57)) \
> __reserved_bits |= X86_CR4_LA57; \
> + if (!__cpu_has(__c, X86_FEATURE_UMIP)) \
> + __reserved_bits |= X86_CR4_UMIP; \
> __reserved_bits; \
> })
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
--
Vitaly
