On Fri, Sep 9, 2016 at 5:11 PM, Stefano Stabellini
<sstabell...@kernel.org> wrote:
> On Fri, 9 Sep 2016, Tamas K Lengyel wrote:
>> When emulating instructions the emulator maintains a small i-cache fetched
>> from the guest memory. Under certain scenarios this memory region may contain
>> instructions that a monitor subscriber would prefer to hide, namely INT3, and
>> instead would prefer to emulate a different instruction in-place.
>>
>> This patch extends the vm_event interface to allow returning this i-cache via
>> the vm_event response.
>>
>> Signed-off-by: Tamas K Lengyel <tamas.leng...@zentific.com>
>>
>> diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
>> index 8398af7..161d149 100644
>> --- a/xen/common/vm_event.c
>> +++ b/xen/common/vm_event.c
>> @@ -407,8 +407,11 @@ void vm_event_resume(struct domain *d, struct
>> vm_event_domain *ved)
>> vm_event_register_write_resume(v, &rsp);
>> break;
>>
>> + case VM_EVENT_REASON_SOFTWARE_BREAKPOINT:
>> + vm_event_interrupt_emulate_check(v, &rsp);
>> + break;
>> +
>> #ifdef CONFIG_HAS_MEM_ACCESS
>> - case VM_EVENT_REASON_MEM_ACCESS:
>> mem_access_resume(v, &rsp);
>> break;
>> #endif
>> diff --git a/xen/include/asm-arm/vm_event.h b/xen/include/asm-arm/vm_event.h
>> index ccc4b60..e56bc78 100644
>> --- a/xen/include/asm-arm/vm_event.h
>> +++ b/xen/include/asm-arm/vm_event.h
>> @@ -40,6 +40,12 @@ static inline void vm_event_toggle_singlestep(struct
>> domain *d, struct vcpu *v)
>> }
>>
>> static inline
>> +void vm_event_interrupt_emulate_check(struct vcpu *v, vm_event_response_t
>> *rsp)
>> +{
>> + /* Not supported on ARM. */
>> +}
>> +
>> +static inline
>> void vm_event_register_write_resume(struct vcpu *v, vm_event_response_t
>> *rsp)
>> {
>> /* Not supported on ARM. */
>
> Doesn't it make sense to return some sort of error?
Not really, there is no path for that error to reach the user who
triggered this via the vm_event response. Usually if there is an error
in the operation specified by the response flag we just print a
message to the Xen console. But since these ops are not supported on
ARM at all - there is no emulator - it would be kind-of be redundant.
Tamas
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
