Commit 697c89be authored by Vipin Sharma's avatar Vipin Sharma Committed by Sean Christopherson
Browse files

KVM: x86/mmu: Consolidate Dirty vs. Writable clearing logic in TDP MMU 

Deduplicate the guts of the TDP MMU's clearing of dirty status by
snapshotting whether to check+clear the Dirty bit vs. the Writable bit,
which is the only difference between the two flavors of dirty tracking.

Note, kvm_ad_enabled() is just a wrapper for shadow_accessed_mask, i.e.
is constant after kvm-{intel,amd}.ko is loaded.

Link: https://lore.kernel.org/all/Yz4Qi7cn7TWTWQjj@google.com


Signed-off-by: default avatarVipin Sharma <vipinsh@google.com>
[sean: split to separate patch, apply to dirty log, write changelog]
Link: https://lore.kernel.org/r/20230321220021.2119033-4-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 5982a539

arch/x86/kvm/mmu/tdp_mmu.c

+9 −26
Original line number Diff line number Diff line
@@ -1607,8 +1607,8 @@ void kvm_tdp_mmu_try_split_huge_pages(struct kvm *kvm, 
static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,

			   gfn_t start, gfn_t end)

{

	u64 dbit = kvm_ad_enabled() ? shadow_dirty_mask : PT_WRITABLE_MASK;

	struct tdp_iter iter;

	u64 new_spte;

	bool spte_set = false;



	rcu_read_lock();
@@ -1624,19 +1624,10 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, 
		MMU_WARN_ON(kvm_ad_enabled() &&

			    spte_ad_need_write_protect(iter.old_spte));



		if (!kvm_ad_enabled()) {

			if (is_writable_pte(iter.old_spte))

				new_spte = iter.old_spte & ~PT_WRITABLE_MASK;

			else

				continue;

		} else {

			if (iter.old_spte & shadow_dirty_mask)

				new_spte = iter.old_spte & ~shadow_dirty_mask;

			else

		if (!(iter.old_spte & dbit))

			continue;

		}



		if (tdp_mmu_set_spte_atomic(kvm, &iter, new_spte))

		if (tdp_mmu_set_spte_atomic(kvm, &iter, iter.old_spte & ~dbit))

			goto retry;



		spte_set = true;
@@ -1678,8 +1669,9 @@ bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, 
static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root,

				  gfn_t gfn, unsigned long mask, bool wrprot)

{

	u64 dbit = (wrprot || !kvm_ad_enabled()) ? PT_WRITABLE_MASK :

						   shadow_dirty_mask;

	struct tdp_iter iter;

	u64 new_spte;



	rcu_read_lock();
@@ -1697,19 +1689,10 @@ static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, 


		mask &= ~(1UL << (iter.gfn - gfn));



		if (wrprot || !kvm_ad_enabled()) {

			if (is_writable_pte(iter.old_spte))

				new_spte = iter.old_spte & ~PT_WRITABLE_MASK;

			else

		if (!(iter.old_spte & dbit))

			continue;

		} else {

			if (iter.old_spte & shadow_dirty_mask)

				new_spte = iter.old_spte & ~shadow_dirty_mask;

			else

				continue;

		}



		tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte);

		tdp_mmu_set_spte_no_dirty_log(kvm, &iter, iter.old_spte & ~dbit);

	}



	rcu_read_unlock();