Re: [PATCH V3 2/13] KVM/MMU: Add tlb flush with range helper function

[Paolo Bonzini]

On 27/09/2018 05:48, Tianyu Lan wrote:
> +
> +	if (range && kvm_x86_ops->tlb_remote_flush_with_range) {
> +		/*
> +		 * Read tlbs_dirty before flushing tlbs in order
> +		 * to track dirty tlbs during flushing.
> +		 */
> +		long dirty_count = smp_load_acquire(&kvm->tlbs_dirty);
> +
> +		ret = kvm_x86_ops->tlb_remote_flush_with_range(kvm, range);
> +		cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);

This is wrong, because it's not the entire TLB that is flushed.  So you
cannot do the cmpxchg here.

Paolo

> +
> +	if (ret)
> +		kvm_flush_remote_tlbs(kvm);
> +}
> +