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KVM: x86/mmu: Factor out spte atomic bit clearing routine

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This new function, tdp_mmu_clear_spte_bits_atomic(), will be used in a
follow-up patch to enable lockless Accessed bit clearing.

Signed-off-by: James Houghton <jthoughton@google.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Link: https://lore.kernel.org/r/20250204004038.1680123-4-jthoughton@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
James Houghton 2025-02-04 00:40:30 +00:00 committed by Sean Christopherson
parent aa34b81165
commit e29b74920e
1 changed files with 9 additions and 6 deletions
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15
arch/x86/kvm/mmu/tdp_iter.h
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@ -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;