powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory

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POWER secure guests (i.e., guests which use the Protected 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().

Fixes: 2efbc58f15 ("powerpc/pseries/svm: Force SWIOTLB for secure guests")
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200818221126.391073-1-bauerman@linux.ibm.com

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Thiago Jung Bauermann 2020-08-18 19:11:26 -03:00 • committed by Michael Ellerman

parent 231b232df8

commit eae9eec476

3 changed files with 35 additions and 1 deletions

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4

arch/powerpc/include/asm/svm.h

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arch/powerpc/mm/mem.c

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26

arch/powerpc/platforms/pseries/svm.c

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