Re: [Xen-devel] [PATCH V3 1/3] xen/mem_access: Support for memory-content hiding

["Lengyel, Tamas" <tlengyel@xxxxxxxxxxx>]

Handy feature, thanks for doing it!

@@ -1466,6 +1466,10 @@ void p2m_mem_access_emulate_check(struct vcpu *v,
         }

         v->arch.vm_event.emulate_flags = violation ? rsp->flags : 0;
+
+        if ( rsp->flags & MEM_ACCESS_SET_EMUL_READ_DATA &&

So one of the use-cases for this feature I would have is using it in the vm_event response to the software breakpoint event. A little bit of context: I have written 0xCC into target memory locations, which are further protected by mem_access R/W. This setup right now would suffice to hide the content easily from the R mem_access events without having to remove it. But for X tracing I'm not using mem_access events. Here this feature is locked to be only in response to a mem_access events. I can *technically* work around that by changing the response type to the mem_access event, but it would be nice if this feature would be clearly available for non-mem_access events as well (or at least for software breakpoint). What do you think, does that usecase make sense here?

Tamas

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