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

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: 2efbc58f157a ("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

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 42e25874f5a8..ddc32cc1b6cf 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -49,6 +49,7 @@
 #include <asm/swiotlb.h>
 #include <asm/rtas.h>
 #include <asm/kasan.h>
+#include <asm/svm.h>
 
 #include <mm/mmu_decl.h>
 
@@ -282,7 +283,10 @@ void __init mem_init(void)
 	 * back to to-down.
 	 */
 	memblock_set_bottom_up(true);
-	swiotlb_init(0);
+	if (is_secure_guest())
+		svm_swiotlb_init();
+	else
+		swiotlb_init(0);
 #endif
 
 	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);