Re: [PATCH v6 13/18] s390x: protvirt: Disable address checks for PV guest IO emulation

[David Hildenbrand]

On 05.03.20 10:42, Janosch Frank wrote:
> On 3/4/20 6:55 PM, David Hildenbrand wrote:
>> On 04.03.20 12:42, Janosch Frank wrote:
>>> IO instruction data is routed through SIDAD for protected guests, so
>>> adresses do not need to be checked, as this is kernel memory.
>>>
>>> Signed-off-by: Janosch Frank <address@hidden>
>>> Reviewed-by: Thomas Huth <address@hidden>
>>> ---
>>>  target/s390x/ioinst.c | 26 +++++++++++++++++++-------
>>>  1 file changed, 19 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
>>> index c437a1d8c6..e4102430aa 100644
>>> --- a/target/s390x/ioinst.c
>>> +++ b/target/s390x/ioinst.c
>>> @@ -17,6 +17,16 @@
>>>  #include "trace.h"
>>>  #include "hw/s390x/s390-pci-bus.h"
>>>  
>>> +static uint64_t get_address_from_regs(CPUS390XState *env, uint32_t ipb,
>>> +                                      uint8_t *ar)
>>> +{
>>
>> Please add a comment here why this is done. (e.g., make all address
>> checks - like alignment checks - in the caller succeed, and we don't
>> need the address).
> 
>      * Addresses for protected guests are all offsets into the
> 
> 
>      * satellite block which holds the IO control structures. Those

maybe mention SIDA as well

> 
> 
>      * control structures are always aligned and accessible, so we can
> 
> 
>      * return 0 here which will pass the following address checks.
> 
> ?


Sounds good!


-- 
Thanks,

David / dhildenb