Re: [PATCH v2 22/28] KVM: x86/mmu: Mark SPTEs in disconnected pages as removed

[Paolo Bonzini]

On 02/02/21 19:57, Ben Gardon wrote:
> +			 * Marking the SPTE as a removed SPTE is not
> +			 * strictly necessary here as the MMU lock should

"should" is a bit too weak---the point of !shared is that the MMU lock 
*will* stop other threads from concurrent modifications of the SPTEs.

Paolo

> +			 * stop other threads from concurrentrly modifying
> +			 * this SPTE. Using the removed SPTE value keeps
> +			 * the shared and non-atomic cases consistent and
> +			 * simplifies the function.
> +			 */
> +			WRITE_ONCE(*sptep, REMOVED_SPTE);