Commit 1f997345 authored by Vipin Sharma's avatar Vipin Sharma Committed by Sean Christopherson
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KVM: x86/mmu: Remove handle_changed_spte_dirty_log() 



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: default avatarVipin Sharma <vipinsh@google.com>
Reviewed-by: default avatarDavid 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: default avatarSean Christopherson <seanjc@google.com>
parent 0b7cc254

arch/x86/kvm/mmu/tdp_mmu.c

+3 −23
Original line number Diff line number Diff line
@@ -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;

}