[Patch v3 6/7] KVM: x86/mmu: Remove handle_changed_spte_dirty_log()

Vipin Sharma
2023-02-11T01:47:06Z

Remove handle_changed_spte_dirty_log() as there is no code flow which
sets 4KiB SPTE writable and hit this path. This function marks the page
dirty in a memslot only if new SPTE is 4KiB in size and writable.

Current users of handle_changed_spte_dirty_log() are:
1. set_spte_gfn() - Create only non writable SPTEs.
2. write_protect_gfn() - Change an SPTE to non writable.
3. zap leaf and roots APIs - Everything is 0.
4. handle_removed_pt() - Sets SPTEs to REMOVED_SPTE
5. tdp_mmu_link_sp() - Makes non leaf SPTEs.

There is also no path which creates a writable 4KiB without going
through make_spte() and this functions takes care of marking SPTE dirty
in the memslot if it is PT_WRITABLE.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 22 ----------------------
1 file changed, 22 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index e50e869bf879..0c031319e901 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -345,24 +345,6 @@ static void handle_changed_spte_acc_track(u64 old_spte, u64 new_spte, int level)
kvm_set_pfn_accessed(spte_to_pfn(old_spte));
}

-static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
- u64 old_spte, u64 new_spte, int level)
-{
- bool pfn_changed;
- struct kvm_memory_slot *slot;
-
- if (level > PG_LEVEL_4K)
- return;
-
- pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte);
-
- if ((!is_writable_pte(old_spte) || pfn_changed) &&
- is_writable_pte(new_spte)) {
- slot = __gfn_to_memslot(__kvm_memslots(kvm, as_id), gfn);
- mark_page_dirty_in_slot(kvm, slot, gfn);
- }
-}
-
static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
kvm_account_pgtable_pages((void *)sp->spt, +1);
@@ -614,8 +596,6 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
__handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level,
shared);
handle_changed_spte_acc_track(old_spte, new_spte, level);
- handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte,
- new_spte, level);
}

/*
@@ -727,8 +707,6 @@ static u64 tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,

__handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, false);
handle_changed_spte_acc_track(old_spte, new_spte, level);
- handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte, new_spte,
- level);
return old_spte;
}

--
2.39.1.581.gbfd45094c4-goog