Re: [Patch v4 03/18] KVM: x86/mmu: Track count of pages in KVM MMU page caches globally

[David Matlack]

On Mon, Mar 06, 2023 at 02:41:12PM -0800, Vipin Sharma wrote:
>
>  static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
>  {
>  	kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache);
> -	kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache);
> +	mutex_lock(&vcpu->arch.mmu_shadow_page_cache_lock);
> +	mmu_free_sp_memory_cache(&vcpu->arch.mmu_shadow_page_cache);
> +	mutex_unlock(&vcpu->arch.mmu_shadow_page_cache_lock);

Is this lock necessary (even when the shrinker is hooked up)?
mmu_free_memory_caches() is only called when KVM fails to create a vCPU
(before it has been added to vcpu_array) or during VM destruction (after
the VM has been removed from vm_list).