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);