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KVM: x86/mmu: Remove handle_changed_spte_dirty_log()

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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>
Reviewed-by: David Matlack <dmatlack@google.com>
[sean: add blurb to __handle_changed_spte()'s comment]
Link: https://lore.kernel.org/r/20230321220021.2119033-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Vipin Sharma 2023-03-21 15:00:20 -07:00 committed by Sean Christopherson
parent 0b7cc2547d
commit 1f9973456e
1 changed files with 3 additions and 23 deletions
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26
arch/x86/kvm/mmu/tdp_mmu.c
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@ -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);
@ -516,7 +498,9 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
* the MMU lock and the operation must synchronize with other
* threads that might be modifying SPTEs.
*
* Handle bookkeeping that might result from the modification of a SPTE.
* Handle bookkeeping that might result from the modification of a SPTE. Note,
* dirty logging updates are handled in common code, not here (see make_spte()
* and fast_pf_fix_direct_spte()).
*/
static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
u64 old_spte, u64 new_spte, int level,
@ -613,8 +597,6 @@ 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);
}
/*
@ -725,8 +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;
}