[PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory

[Thiago Jung Bauermann]

Konrad Rzeszutek Wilk <konrad.wilk at oracle.com> writes:

> On Tue, Aug 18, 2020 at 07:11:26PM -0300, Thiago Jung Bauermann wrote:
>> POWER secure guests (i.e., guests which use the Protection Execution
>> Facility) need to use SWIOTLB to be able to do I/O with the hypervisor, but
>> they don't need the SWIOTLB memory to be in low addresses since the
>> hypervisor doesn't have any addressing limitation.
>> 
>> This solves a SWIOTLB initialization problem we are seeing in secure guests
>> with 128 GB of RAM: they are configured with 4 GB of crashkernel reserved
>> memory, which leaves no space for SWIOTLB in low addresses.
>> 
>> To do this, we use mostly the same code as swiotlb_init(), but allocate the
>> buffer using memblock_alloc() instead of memblock_alloc_low().
>> 
>> Signed-off-by: Thiago Jung Bauermann <bauerman at linux.ibm.com>
>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>

Thanks!

-- 
Thiago Jung Bauermann
IBM Linux Technology Center