Re: [PATCH] KVM: MMU: Disassociate direct maps from guest levels

[Marcelo Tosatti <mtosatti@redhat.com>]

On Sun, Mar 14, 2010 at 10:22:52AM +0200, Avi Kivity wrote:
> Direct maps are linear translations for a section of memory, used for
> real mode or with large pages.  As such, they are independent of the guest
> levels.
> 
> Teach the mmu about this by making page->role.glevels = 0 for direct maps.
> This allows direct maps to be shared among real mode and the various paging
> modes.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  arch/x86/kvm/mmu.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index b137515..a984bc1 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -1328,6 +1328,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
>  	role = vcpu->arch.mmu.base_role;
>  	role.level = level;
>  	role.direct = direct;
> +	if (role.direct)
> +		role.glevels = 0;
>  	role.access = access;
>  	if (vcpu->arch.mmu.root_level <= PT32_ROOT_LEVEL) {
>  		quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
> -- 
> 1.7.0.2

Isnt this what happens already, since for tdp base_role.glevels is not 
initialized?