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    SubjectRe: [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory
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    Konrad Rzeszutek Wilk <konrad.wilk@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@linux.ibm.com>
    >
    > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

    Thanks!

    --
    Thiago Jung Bauermann
    IBM Linux Technology Center

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