Re: [Xen-devel] [PATCH v2 06/19] x86/pv: Implement pv_inject_{event, page_fault, hw_exception}()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 28/11/16 11:58, Tim Deegan wrote:
> At 11:13 +0000 on 28 Nov (1480331603), Andrew Cooper wrote:
>> To help with event injection improvements for the PV uses of x86_emulate(),
>> implement a event injection API which matches its hvm counterpart.
>>
>> This is started with taking do_guest_trap() and modifying its calling API to
>> pv_inject_event(), subsequentally implementing the former in terms of the
>> latter.
>>
>> The existing propagate_page_fault() is fairly similar to
>> pv_inject_page_fault(), although it has a return value.  Only a single caller
>> makes use of the return value, and non-NULL is only returned if the passed 
>> cr2
>> is non-canonical.  Opencode this single case in
>> handle_gdt_ldt_mapping_fault(), allowing propagate_page_fault() to become
>> void.
>>
>> The #PF specific bits are moved into pv_inject_event(), and
>> pv_inject_page_fault() is implemented as a static inline wrapper.
>> reserved_bit_page_fault() is pure code motion.
>>
>> No functional change.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Acked-by: Tim Deegan <tim@xxxxxxx>
>
> with one note:
>
>> +    if ( vector == TRAP_page_fault )
>> +    {
>> +        v->arch.pv_vcpu.ctrlreg[2] = event->cr2;
>> +        arch_set_cr2(v, event->cr2);
>> +
>> +        /* Re-set error_code.user flag appropriately for the guest. */
>> +        error_code &= ~PFEC_user_mode;
>> +        if ( !guest_kernel_mode(v, regs) )
>> +            error_code |= PFEC_user_mode;
> I can see that you're just moving this code, but isn't it wrong for
> what are now called "implicit" accesses?  My Ack stands on this patch
> regardless.

One swamp at a time. :)

I have an equally sized series for that mess.

~Andrew

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