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

[Janosch Frank <frankja@linux.ibm.com>]

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On 3/5/20 11:00 AM, David Hildenbrand wrote:
> 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 <frankja@linux.ibm.com>
>>>> Reviewed-by: Thomas Huth <thuth@redhat.com>
>>>> ---
>>>>  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

huh? SIDA is the satellite block

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



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