From: Vipin Sharma <vipinsh@google.com>
To: seanjc@google.com, pbonzini@redhat.com, bgardon@google.com,
dmatlack@google.com
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Vipin Sharma <vipinsh@google.com>
Subject: [Patch v3 4/7] KVM: x86/mmu: Optimize SPTE change for aging gfn range
Date: Fri, 10 Feb 2023 17:46:23 -0800 [thread overview]
Message-ID: <20230211014626.3659152-5-vipinsh@google.com> (raw)
In-Reply-To: <20230211014626.3659152-1-vipinsh@google.com>
No need to check all of the conditions in __handle_changed_spte(). Aging
a gfn range implies resetting access bit or marking spte for access
tracking.
Use atomic operation to only reset those bits. This avoids checking many
conditions in __handle_changed_spte() API. Also, clean up code by
removing dead code and API parameters.
Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 36 +++++++++++++++++++-----------------
1 file changed, 19 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index c895560244de..5d6e77554797 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -758,13 +758,6 @@ static inline void tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
_tdp_mmu_set_spte(kvm, iter, new_spte, true);
}
-static inline void tdp_mmu_set_spte_no_acc_track(struct kvm *kvm,
- struct tdp_iter *iter,
- u64 new_spte)
-{
- _tdp_mmu_set_spte(kvm, iter, new_spte, false);
-}
-
#define tdp_root_for_each_pte(_iter, _root, _start, _end) \
for_each_tdp_pte(_iter, _root, _start, _end)
@@ -1251,32 +1244,41 @@ static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm,
/*
* Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero
* if any of the GFNs in the range have been accessed.
+ *
+ * No need to mark corresponding PFN as accessed as this call is coming from
+ * the clear_young() or clear_flush_young() notifier, which uses the return
+ * value to determine if the page has been accessed.
*/
static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter,
struct kvm_gfn_range *range)
{
- u64 new_spte = 0;
+ u64 new_spte;
/* If we have a non-accessed entry we don't need to change the pte. */
if (!is_accessed_spte(iter->old_spte))
return false;
- new_spte = iter->old_spte;
-
- if (spte_ad_enabled(new_spte)) {
- new_spte &= ~shadow_accessed_mask;
+ if (spte_ad_enabled(iter->old_spte)) {
+ iter->old_spte = tdp_mmu_clear_spte_bits(iter->sptep,
+ iter->old_spte,
+ shadow_accessed_mask,
+ iter->level);
+ new_spte = iter->old_spte & ~shadow_accessed_mask;
} else {
+ new_spte = mark_spte_for_access_track(iter->old_spte);
+ iter->old_spte = kvm_tdp_mmu_write_spte(iter->sptep,
+ iter->old_spte, new_spte,
+ iter->level);
/*
* Capture the dirty status of the page, so that it doesn't get
* lost when the SPTE is marked for access tracking.
*/
- if (is_writable_pte(new_spte))
- kvm_set_pfn_dirty(spte_to_pfn(new_spte));
-
- new_spte = mark_spte_for_access_track(new_spte);
+ if (is_writable_pte(iter->old_spte))
+ kvm_set_pfn_dirty(spte_to_pfn(iter->old_spte));
}
- tdp_mmu_set_spte_no_acc_track(kvm, iter, new_spte);
+ trace_kvm_tdp_mmu_spte_changed(iter->as_id, iter->gfn, iter->level,
+ iter->old_spte, new_spte);
return true;
}
--
2.39.1.581.gbfd45094c4-goog
next prev parent reply other threads:[~2023-02-11 1:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-11 1:46 [Patch v3 0/7] Optimize clear dirty log Vipin Sharma
2023-02-11 1:46 ` [Patch v3 1/7] KVM: x86/mmu: Add a helper function to check if an SPTE needs atomic write Vipin Sharma
2023-02-11 1:46 ` [Patch v3 2/7] KVM: x86/mmu: Atomically clear SPTE dirty state in the clear-dirty-log flow Vipin Sharma
2023-02-15 21:12 ` David Matlack
2023-03-17 22:59 ` Sean Christopherson
2023-03-17 23:50 ` Vipin Sharma
2023-02-11 1:46 ` [Patch v3 3/7] KVM: x86/mmu: Remove "record_dirty_log" in __tdp_mmu_set_spte() Vipin Sharma
2023-02-15 21:10 ` David Matlack
2023-02-11 1:46 ` Vipin Sharma [this message]
2023-02-15 21:15 ` [Patch v3 4/7] KVM: x86/mmu: Optimize SPTE change for aging gfn range David Matlack
2023-03-21 0:51 ` Sean Christopherson
2023-02-11 1:46 ` [Patch v3 5/7] KVM: x86/mmu: Remove "record_acc_track" in __tdp_mmu_set_spte() Vipin Sharma
2023-02-22 19:31 ` David Matlack
2023-02-11 1:46 ` [Patch v3 6/7] KVM: x86/mmu: Remove handle_changed_spte_dirty_log() Vipin Sharma
2023-02-22 19:36 ` David Matlack
2023-02-11 1:46 ` [Patch v3 7/7] KVM: x86/mmu: Merge all handle_changed_pte* functions Vipin Sharma
2023-02-22 19:42 ` David Matlack
2023-03-17 22:51 ` Sean Christopherson
2023-03-17 23:48 ` Vipin Sharma
2023-03-17 22:57 ` [Patch v3 0/7] Optimize clear dirty log Sean Christopherson
2023-03-17 23:51 ` Vipin Sharma
2023-03-21 0:41 ` Sean Christopherson
2023-03-21 18:11 ` Vipin Sharma
2023-03-21 19:57 ` Sean Christopherson
2023-03-21 20:40 ` Sean Christopherson
2023-03-21 21:38 ` Sean Christopherson
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