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Message-ID: <20241105184333.2305744-4-jthoughton@google.com>
Date: Tue, 5 Nov 2024 18:43:25 +0000
From: James Houghton <jthoughton@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: David Matlack <dmatlack@...gle.com>, David Rientjes <rientjes@...gle.com>,
James Houghton <jthoughton@...gle.com>, Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>, Wei Xu <weixugc@...gle.com>, Yu Zhao <yuzhao@...gle.com>,
Axel Rasmussen <axelrasmussen@...gle.com>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v8 03/11] KVM: x86/mmu: Factor out spte atomic bit clearing routine
This new function, tdp_mmu_clear_spte_bits_atomic(), will be used in a
follow-up patch to enable lockless Accessed and R/W/X bit clearing.
Signed-off-by: James Houghton <jthoughton@...gle.com>
---
arch/x86/kvm/mmu/tdp_iter.h | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h
index 2880fd392e0c..a24fca3f9e7f 100644
--- a/arch/x86/kvm/mmu/tdp_iter.h
+++ b/arch/x86/kvm/mmu/tdp_iter.h
@@ -25,6 +25,13 @@ static inline u64 kvm_tdp_mmu_write_spte_atomic(tdp_ptep_t sptep, u64 new_spte)
return xchg(rcu_dereference(sptep), new_spte);
}
+static inline u64 tdp_mmu_clear_spte_bits_atomic(tdp_ptep_t sptep, u64 mask)
+{
+ atomic64_t *sptep_atomic = (atomic64_t *)rcu_dereference(sptep);
+
+ return (u64)atomic64_fetch_and(~mask, sptep_atomic);
+}
+
static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte)
{
KVM_MMU_WARN_ON(is_ept_ve_possible(new_spte));
@@ -63,12 +70,8 @@ static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte,
static inline u64 tdp_mmu_clear_spte_bits(tdp_ptep_t sptep, u64 old_spte,
u64 mask, int level)
{
- atomic64_t *sptep_atomic;
-
- if (kvm_tdp_mmu_spte_need_atomic_write(old_spte, level)) {
- sptep_atomic = (atomic64_t *)rcu_dereference(sptep);
- return (u64)atomic64_fetch_and(~mask, sptep_atomic);
- }
+ if (kvm_tdp_mmu_spte_need_atomic_write(old_spte, level))
+ return tdp_mmu_clear_spte_bits_atomic(sptep, mask);
__kvm_tdp_mmu_write_spte(sptep, old_spte & ~mask);
return old_spte;
--
2.47.0.199.ga7371fff76-goog
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