[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] vm_event: Implement ARM SMC events
Hello Corneliu, On 13/04/16 09:55, Corneliu ZUZU wrote: On 4/12/2016 8:24 PM, Tamas K Lengyel wrote: Another issue came to my mind: "HVC #imm", if handled through the hvm-ops code, currently requires setting other registers to predefined values before the HVC is actually issued. That would imply additional effort to save/restore those registers if an external privileged domain would want to set guest breakpoints. Given that, if we were to use HVC for sw-bkpts, IMO it would be nice if the hvm-ops code architecture would be slightly changed such that -lone- "HVM #imm" calls would be achievable for some use cases, such as this. That is not true. All the hypercalls are using the same #imm (XEN_HYPERCALL_TAG = 0xEA1), which indeed requires specific value in various registers to differentiate the HVM-ops. It's up to us to define the requirements for the other #imm. For instance there are some #imm allocated for debugging (see do_debug_trap) that will dump the content of the registers. So what I will do instead of issuing a software_breakpoint vm_event for SMCs, I'll introduce a new type, say VM_EVENT_REASON_PRIVILEGED_CALL, that can be used to forward both hypercalls and SMCs to a monitoring guest. This would also allow us to use the software_breakpoint type for the actual software breakpoint events in the future. TamasIsn't the HVC-part already achieved by guest-request vm-events? Maybe tying this vm-event specifically to SMC (in which case the name could be something like VM_EVENT_REASON_SECURE_CALL) and thus making it ARM-specific would avoid that redundancy? I would create 2 distinct events for HVC and SMC. It would make easier to differentiate them in userspace. Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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