Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes:
> Alternative patch: remove the filtering from kvm_mmu_get_page() and check
> for direct on call sites. cr4_pae setting in kvm_calc_mmu_role_common()
> can be preserved for consistency.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index f2d1d230d5b8..7fb8118f2af6 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2420,8 +2420,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
> role = vcpu->arch.mmu->mmu_role.base;
> role.level = level;
> role.direct = direct;
> - if (role.direct)
> - role.cr4_pae = 0;
> role.access = access;
> if (!vcpu->arch.mmu->direct_map
> && vcpu->arch.mmu->root_level <= PT32_ROOT_LEVEL) {
> @@ -5176,7 +5174,7 @@ static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa,
> gpa, bytes, sp->role.word);
>
> offset = offset_in_page(gpa);
> - pte_size = sp->role.cr4_pae ? 8 : 4;
> + pte_size = (sp->role.cr4_pae && !sp->role.direct) ? 8 : 4;
>
> /*
> * Sometimes, the OS only writes the last one bytes to update status
> @@ -5200,7 +5198,7 @@ static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte)
> page_offset = offset_in_page(gpa);
> level = sp->role.level;
> *nspte = 1;
> - if (!sp->role.cr4_pae) {
> + if (!sp->role.cr4_pae || sp->role.direct) {
> page_offset <<= 1; /* 32->64 */
> /*
> * A 32-bit pde maps 4MB while the shadow pdes map
While I personally prefer this approach to not setting role.cr4_pae in
kvm_calc_mmu_role_common() I'd like to get maintainers opinion (I did
test the patch with ept=off but I have to admit I don't know much about
shadow page tables which actually use detect_write_misaligned()/
get_written_sptes())
Paolo, Radim, (anyone else) - any thoughts?
--
Vitaly
