On Wed, Feb 2, 2022 at 5:02 PM David Matlack <dmatlack@xxxxxxxxxx> wrote:
>
> Separate the code that allocates a new shadow page from the vCPU caches
> from the code that initializes it. This is in preparation for creating
> new shadow pages from VM ioctls for eager page splitting, where we do
> not have access to the vCPU caches.
>
> No functional change intended.
>
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu/mmu.c | 44 +++++++++++++++++++++---------------------
> 1 file changed, 22 insertions(+), 22 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 49f82addf4b5..d4f90a10b652 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1718,7 +1718,7 @@ static void drop_parent_pte(struct kvm_mmu_page *sp,
> mmu_spte_clear_no_track(parent_pte);
> }
>
> -static struct kvm_mmu_page *kvm_mmu_alloc_sp(struct kvm_vcpu *vcpu, int direct)
> +static struct kvm_mmu_page *kvm_mmu_alloc_sp(struct kvm_vcpu *vcpu, bool direct)
> {
> struct kvm_mmu_page *sp;
>
> @@ -1726,16 +1726,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_sp(struct kvm_vcpu *vcpu, int direct)
> sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
> if (!direct)
> sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
> - set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
I'd be inclined to leave this in the allocation function instead of
moving it to the init function. It might not be any less code, but if
you're doing the sp -> page link here, you might as well do the page
-> sp link too.
>
>
> - /*
> - * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages()
> - * depends on valid pages being added to the head of the list. See
> - * comments in kvm_zap_obsolete_pages().
> - */
> - sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
> - list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
> - kvm_mod_used_mmu_pages(vcpu->kvm, +1);
> return sp;
> }
>
> @@ -2144,27 +2135,34 @@ static struct kvm_mmu_page *kvm_mmu_get_existing_sp(struct kvm_vcpu *vcpu,
> return sp;
> }
>
> -static struct kvm_mmu_page *kvm_mmu_create_sp(struct kvm_vcpu *vcpu,
> - struct kvm_memory_slot *slot,
> - gfn_t gfn,
> - union kvm_mmu_page_role role)
> +
> +static void kvm_mmu_init_sp(struct kvm *kvm, struct kvm_mmu_page *sp,
> + struct kvm_memory_slot *slot, gfn_t gfn,
> + union kvm_mmu_page_role role)
> {
> - struct kvm_mmu_page *sp;
> struct hlist_head *sp_list;
>
> - ++vcpu->kvm->stat.mmu_cache_miss;
> + ++kvm->stat.mmu_cache_miss;
> +
> + set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
>
> - sp = kvm_mmu_alloc_sp(vcpu, role.direct);
> sp->gfn = gfn;
> sp->role = role;
> + sp->mmu_valid_gen = kvm->arch.mmu_valid_gen;
>
> - sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
> + /*
> + * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages()
> + * depends on valid pages being added to the head of the list. See
> + * comments in kvm_zap_obsolete_pages().
> + */
> + list_add(&sp->link, &kvm->arch.active_mmu_pages);
> + kvm_mod_used_mmu_pages(kvm, 1);
> +
> + sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
> hlist_add_head(&sp->hash_link, sp_list);
>
> if (!role.direct)
> - account_shadowed(vcpu->kvm, slot, sp);
> -
> - return sp;
> + account_shadowed(kvm, slot, sp);
> }
>
> static struct kvm_mmu_page *kvm_mmu_get_sp(struct kvm_vcpu *vcpu, gfn_t gfn,
> @@ -2179,8 +2177,10 @@ static struct kvm_mmu_page *kvm_mmu_get_sp(struct kvm_vcpu *vcpu, gfn_t gfn,
> goto out;
>
> created = true;
> + sp = kvm_mmu_alloc_sp(vcpu, role.direct);
> +
> slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
> - sp = kvm_mmu_create_sp(vcpu, slot, gfn, role);
> + kvm_mmu_init_sp(vcpu->kvm, sp, slot, gfn, role);
>
> out:
> trace_kvm_mmu_get_page(sp, created);
> --
> 2.35.0.rc2.247.g8bbb082509-goog
>
