Re: [PATCH v2 3/3] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server

["Yu, Zhang" <yu.c.zhang@linux.intel.com>]

Thanks, Tim.

On 4/4/2016 4:25 PM, Tim Deegan wrote:
> At 18:53 +0800 on 31 Mar (1459450418), Yu Zhang wrote:
>> A new HVMOP - HVMOP_map_mem_type_to_ioreq_server, is added to
>> let one ioreq server claim/disclaim its responsibility for the
>> handling of guest pages with p2m type p2m_ioreq_server. Users
>> of this HVMOP can specify whether the p2m_ioreq_server is supposed
>> to handle write accesses or read ones or both in a parameter named
>> flags. For now, we only support one ioreq server for this p2m type,
>> so once an ioreq server has claimed its ownership, subsequent calls
>> of the HVMOP_map_mem_type_to_ioreq_server will fail. Users can also
>> disclaim the ownership of guest ram pages with this p2m type, by
>> triggering this new HVMOP, with ioreq server id set to the current
>> owner's and flags parameter set to 0.
>>
>> For now, both HVMOP_map_mem_type_to_ioreq_server and p2m_ioreq_server
>> are only supported for HVMs with HAP enabled.
>
> "For now", meaning you intend to make this work on shadow pagetables? :P
> If not, please just say it's HAP-only.
>

Well, I have no clear plan in the near future to support this on shadow
mode, and I'll change the commit message in next version. :)

>> diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
>> index c81302a..2e0d258 100644
>> --- a/xen/arch/x86/mm/shadow/multi.c
>> +++ b/xen/arch/x86/mm/shadow/multi.c
>> @@ -3224,8 +3224,7 @@ static int sh_page_fault(struct vcpu *v,
>>       }
>>
>>       /* Need to hand off device-model MMIO to the device model */
>> -    if ( p2mt == p2m_mmio_dm
>> -         || (p2mt == p2m_ioreq_server && ft == ft_demand_write) )
>> +    if ( p2mt == p2m_mmio_dm )
>>       {
>>           gpa = guest_walk_to_gpa(&gw);
>>           goto mmio;
>
> Acked-by: Tim Deegan <tim@xen.org>
>
>

Regards.
Yu

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