On Fri, 2022-03-04 at 11:49 -0800, isaku.yamahata@xxxxxxxxx wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> SPTE_PRIVATE_PROHIBIT specifies the share or private GPA is allowed or not.
> It needs to be kept over zapping the EPT entry. Currently the EPT entry is
> initialized shadow_init_value unconditionally to clear
> SPTE_PRIVATE_PROHIBIT bit. To carry SPTE_PRIVATE_PROHIBIT bit, introduce a
> helper function to get initial value for zapped entry with
> SPTE_PRIVATE_PROHIBIT bit. Replace shadow_init_value with it.
Isn't it better to merge patch 53-55, especially 54-55 together?
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ---
> arch/x86/kvm/mmu/tdp_mmu.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 1949f81027a0..6d750563824d 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -610,6 +610,12 @@ static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
> return true;
> }
>
> +static u64 shadow_init_spte(u64 old_spte)
> +{
> + return shadow_init_value |
> + (is_private_prohibit_spte(old_spte) ? SPTE_PRIVATE_PROHIBIT : 0);
> +}
> +
> static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm,
> struct tdp_iter *iter)
> {
> @@ -641,7 +647,8 @@ static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm,
> * shadow_init_value (which sets "suppress #VE" bit) so it
> * can be set when EPT table entries are zapped.
> */
> - WRITE_ONCE(*rcu_dereference(iter->sptep), shadow_init_value);
> + WRITE_ONCE(*rcu_dereference(iter->sptep),
> + shadow_init_spte(iter->old_spte));
>
> return true;
> }
In this and next patch (54-55), in all the code path, you already have the iter-
>sptep, from which you can get the sp->private_sp, and check using
is_private_sp(). Why do we need this SPTE_PRIVATE_PRORHIBIT bit?
Are you suggesting we can have mixed private/shared mapping under a private_sp?
> @@ -853,7 +860,8 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
>
> if (!shared) {
> /* see comments in tdp_mmu_zap_spte_atomic() */
> - tdp_mmu_set_spte(kvm, &iter, shadow_init_value);
> + tdp_mmu_set_spte(kvm, &iter,
> + shadow_init_spte(iter.old_spte));
> flush = true;
> } else if (!tdp_mmu_zap_spte_atomic(kvm, &iter)) {
> /*
> @@ -1038,11 +1046,14 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
> new_spte = make_mmio_spte(vcpu,
> tdp_iter_gfn_unalias(vcpu->kvm, iter),
> pte_access);
> - else
> + else {
> wrprot = make_spte(vcpu, sp, fault->slot, pte_access,
> tdp_iter_gfn_unalias(vcpu->kvm, iter),
> fault->pfn, iter->old_spte, fault->prefetch,
> true, fault->map_writable, &new_spte);
> + if (is_private_prohibit_spte(iter->old_spte))
> + new_spte |= SPTE_PRIVATE_PROHIBIT;
> + }
>
> if (new_spte == iter->old_spte)
> ret = RET_PF_SPURIOUS;
> @@ -1335,7 +1346,7 @@ static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter,
> * invariant that the PFN of a present * leaf SPTE can never change.
> * See __handle_changed_spte().
> */
> - tdp_mmu_set_spte(kvm, iter, shadow_init_value);
> + tdp_mmu_set_spte(kvm, iter, shadow_init_spte(iter->old_spte));
>
> if (!pte_write(range->pte)) {
> new_spte = kvm_mmu_changed_pte_notifier_make_spte(iter->old_spte,
