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KVM: x86/mmu: Fold set_external_spte_present() into its sole caller

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Fold set_external_spte_present() into __tdp_mmu_set_spte_atomic() in
anticipation of propagating *all* changes (like atomic zap) triggered by
tdp_mmu_set_spte_atomic() to the external PTEs.

No functional change intended.

Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://patch.msgid.link/20260509075520.4177-1-yan.y.zhao@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2026-05-09 15:55:19 +08:00
parent 176dcd88f4
commit 78d23e299b
1 changed files with 31 additions and 41 deletions
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72
arch/x86/kvm/mmu/tdp_mmu.c
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@ -495,33 +495,6 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback);
}
static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sptep,
gfn_t gfn, u64 *old_spte,
u64 new_spte, int level)
{
bool was_present = is_shadow_present_pte(*old_spte);
int ret;
KVM_BUG_ON(was_present, kvm);
lockdep_assert_held(&kvm->mmu_lock);
/*
* We need to lock out other updates to the SPTE until the external
* page table has been modified. Use FROZEN_SPTE similar to
* the zapping case.
*/
if (!try_cmpxchg64(rcu_dereference(sptep), old_spte, FROZEN_SPTE))
return -EBUSY;
ret = kvm_x86_call(set_external_spte)(kvm, gfn, level, new_spte);
if (ret)
__kvm_tdp_mmu_write_spte(sptep, *old_spte);
else
__kvm_tdp_mmu_write_spte(sptep, new_spte);
return ret;
}
/**
* handle_changed_spte - handle bookkeeping associated with an SPTE change
* @kvm: kvm instance
@ -626,6 +599,8 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm,
struct tdp_iter *iter,
u64 new_spte)
{
u64 *raw_sptep = rcu_dereference(iter->sptep);
/*
* The caller is responsible for ensuring the old SPTE is not a FROZEN
* SPTE. KVM should never attempt to zap or manipulate a FROZEN SPTE,
@ -635,8 +610,13 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm,
WARN_ON_ONCE(iter->yielded || is_frozen_spte(iter->old_spte));
if (is_mirror_sptep(iter->sptep) && !is_frozen_spte(new_spte)) {
bool was_present = is_shadow_present_pte(iter->old_spte);
int ret;
KVM_BUG_ON(was_present, kvm);
lockdep_assert_held(&kvm->mmu_lock);
/*
* Users of atomic zapping don't operate on mirror roots,
* so don't handle it and bug the VM if it's seen.
@ -644,25 +624,35 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm,
if (KVM_BUG_ON(!is_shadow_present_pte(new_spte), kvm))
return -EBUSY;
ret = set_external_spte_present(kvm, iter->sptep, iter->gfn,
&iter->old_spte, new_spte, iter->level);
if (ret)
return ret;
} else {
u64 *sptep = rcu_dereference(iter->sptep);
/*
* Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs
* and does not hold the mmu_lock. On failure, i.e. if a
* different logical CPU modified the SPTE, try_cmpxchg64()
* updates iter->old_spte with the current value, so the caller
* operates on fresh data, e.g. if it retries
* tdp_mmu_set_spte_atomic()
* We need to lock out other updates to the SPTE until the external
* page table has been modified. Use FROZEN_SPTE similar to
* the zapping case.
*/
if (!try_cmpxchg64(sptep, &iter->old_spte, new_spte))
if (!try_cmpxchg64(raw_sptep, &iter->old_spte, FROZEN_SPTE))
return -EBUSY;
ret = kvm_x86_call(set_external_spte)(kvm, iter->gfn, iter->level,
new_spte);
if (ret)
__kvm_tdp_mmu_write_spte(iter->sptep, iter->old_spte);
else
__kvm_tdp_mmu_write_spte(iter->sptep, new_spte);
return ret;
}
/*
* Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs and
* does not hold the mmu_lock. On failure, i.e. if a different logical
* CPU modified the SPTE, try_cmpxchg64() updates iter->old_spte with
* the current value, so the caller operates on fresh data, e.g. if it
* retries tdp_mmu_set_spte_atomic().
*/
if (!try_cmpxchg64(raw_sptep, &iter->old_spte, new_spte))
return -EBUSY;
return 0;
}