Re: [PATCH RFC 02/10] KVM: Allow reading memslots while holding slots_arch_lock
From: Sean Christopherson <seanjc@google.com>
Date: 2026-09-10 16:30:25
Also in:
kvm, lkml
On Thu, Sep 10, 2026, Marco Elver wrote:
kvm_swap_active_memslots() updates kvm->memslots[as_id] while holding both kvm->slots_lock and kvm->slots_arch_lock. Holding either lock guarantees that memslots cannot be concurrently modified.
Sure, but that's irrelevant. The goal of the srcu_dereference_check() is to ensure that readers see a stable view of the VM's overall memory, not simply that kvm->memslots can't be written.
Allow reading memslots in __kvm_memslots() when kvm->slots_arch_lock is held.
Why?
quoted hunk ↗ jump to hunk
Signed-off-by: Marco Elver <elver@google.com> --- include/linux/kvm_host.h | 1 + 1 file changed, 1 insertion(+)diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 03bfc92864b6..5ed8260ef01f 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h@@ -1089,6 +1089,7 @@ static inline struct kvm_memslots *__kvm_memslots(struct kvm *kvm, int as_id) as_id = array_index_nospec(as_id, KVM_MAX_NR_ADDRESS_SPACES); return srcu_dereference_check(kvm->memslots[as_id], &kvm->srcu, lockdep_is_held(&kvm->slots_lock) || + lockdep_is_held(&kvm->slots_arch_lock) || !refcount_read(&kvm->users_count)); }-- 2.55.0.1003.g10538fe699-goog