Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:
> Explicitly zero out quadrant and invalid instead of inheriting them from
> the root_mmu. Functionally, this patch is a nop as we (should) never
> set quadrant for a direct mapped (EPT) root_mmu and nested EPT is only
> allowed if EPT is used for L1, and the root_mmu will never be invalid at
> this point.
>
> Explicitly setting flags sets the stage for repurposing the legacy
> paging bits in role, e.g. nxe, cr0_wp, and sm{a,e}p_andnot_wp, at which
> point 'smm' would be the only flag to be inherited from root_mmu.
>
> Tested-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index e55cebbe7918..71098f2ae870 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -4917,11 +4917,15 @@ static union kvm_mmu_role
> kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
> bool execonly)
> {
> - union kvm_mmu_role role;
> + union kvm_mmu_role role = {0};
> + union kvm_mmu_page_role root_base = vcpu->arch.root_mmu.mmu_role.base;
>
> - /* Base role is inherited from root_mmu */
> - role.base.word = vcpu->arch.root_mmu.mmu_role.base.word;
> - role.ext = kvm_calc_mmu_role_ext(vcpu);
> + /* Legacy paging and SMM flags are inherited from root_mmu */
> + role.base.smm = root_base.smm;
> + role.base.nxe = root_base.nxe;
> + role.base.cr0_wp = root_base.cr0_wp;
> + role.base.smep_andnot_wp = root_base.smep_andnot_wp;
> + role.base.smap_andnot_wp = root_base.smap_andnot_wp;
>
> role.base.level = PT64_ROOT_4LEVEL;
> role.base.direct = false;
> @@ -4929,6 +4933,7 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
> role.base.guest_mode = true;
> role.base.access = ACC_ALL;
>
> + role.ext = kvm_calc_mmu_role_ext(vcpu);
> role.ext.execonly = execonly;
>
> return role;
--
Vitaly
