Re: [PATCH v9 11/15] s390x: protvirt: Disable address checks for PV guest IO emulation

[Janosch Frank]

On 3/12/20 5:10 PM, Christian Borntraeger wrote:
> 
> 
> On 12.03.20 17:07, Janosch Frank wrote:
>> On 3/12/20 4:41 PM, Christian Borntraeger wrote:
>>> On 11.03.20 14:21, 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.
>>>
>>> Maybe also mention that the data structures for  the I/O instrutions
>>> start at offset 0 of the SIDA?
>>
>> You mean in the comment for get_address_from_regs() or in the commit
>> message? It would certainly make sense for get_address_from_regs().
> 
> Maybe both?
> 

This is what I have now:

s390x: protvirt: Disable address checks for PV guest IO emulation

IO instruction data is routed through SIDAD for protected guests, so
adresses do not need to be checked, as this is kernel memory which is
always available.

Also the instruction data always starts at offset 0 of the SIDAD.

Signed-off-by: Janosch Frank <address@hidden>
Reviewed-by: Thomas Huth <address@hidden>
Reviewed-by: David Hildenbrand <address@hidden>
Reviewed-by: Christian Borntraeger <address@hidden>

and

+    /*


+     * Addresses for protected guests are all offsets into the


+     * satellite block which holds the IO control structures. Those


+     * control structures are always starting at offset 0 and are


+     * always aligned and accessible. So we can return 0 here which


+     * will pass the following address checks.


+     */

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