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

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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: Vipin 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: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Vipin Sharma 2023-03-21 15:00:11 -07:00 committed by Sean Christopherson
parent 5982a53926
commit 697c89bed9
1 changed files with 9 additions and 26 deletions
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35
arch/x86/kvm/mmu/tdp_mmu.c
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@ -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 @@ retry:
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
continue;
}
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
continue;
} else {
if (iter.old_spte & shadow_dirty_mask)
new_spte = iter.old_spte & ~shadow_dirty_mask;
else
continue;
}
if (!(iter.old_spte & dbit))
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();