Commit eae9eec4 authored by Thiago Jung Bauermann's avatar Thiago Jung Bauermann Committed by Michael Ellerman
Browse files

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: 2efbc58f ("powerpc/pseries/svm: Force SWIOTLB for secure guests")
Signed-off-by: default avatarThiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200818221126.391073-1-bauerman@linux.ibm.com
parent 231b232d

arch/powerpc/include/asm/svm.h

+4 −0
Original line number Diff line number Diff line
@@ -15,6 +15,8 @@ static inline bool is_secure_guest(void) 
	return mfmsr() & MSR_S;

}



void __init svm_swiotlb_init(void);



void dtl_cache_ctor(void *addr);

#define get_dtl_cache_ctor()	(is_secure_guest() ? dtl_cache_ctor : NULL)
@@ -25,6 +27,8 @@ static inline bool is_secure_guest(void) 
	return false;

}



static inline void svm_swiotlb_init(void) {}



#define get_dtl_cache_ctor() NULL



#endif /* CONFIG_PPC_SVM */

arch/powerpc/mm/mem.c

+5 −1
Original line number Diff line number Diff line
@@ -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>
@@ -282,6 +283,9 @@ void __init mem_init(void) 
	 * back to to-down.

	 */

	memblock_set_bottom_up(true);

	if (is_secure_guest())

		svm_swiotlb_init();

	else

		swiotlb_init(0);

#endif

arch/powerpc/platforms/pseries/svm.c

+26 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
 */



#include <linux/mm.h>

#include <linux/memblock.h>

#include <asm/machdep.h>

#include <asm/svm.h>

#include <asm/swiotlb.h>
@@ -35,6 +36,31 @@ static int __init init_svm(void) 
}

machine_early_initcall(pseries, init_svm);



/*

 * Initialize SWIOTLB. Essentially the same as swiotlb_init(), except that it

 * can allocate the buffer anywhere in memory. Since the hypervisor doesn't have

 * any addressing limitation, we don't need to allocate it in low addresses.

 */

void __init svm_swiotlb_init(void)

{

	unsigned char *vstart;

	unsigned long bytes, io_tlb_nslabs;



	io_tlb_nslabs = (swiotlb_size_or_default() >> IO_TLB_SHIFT);

	io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);



	bytes = io_tlb_nslabs << IO_TLB_SHIFT;



	vstart = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE);

	if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, false))

		return;



	if (io_tlb_start)

		memblock_free_early(io_tlb_start,

				    PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));

	panic("SVM: Cannot allocate SWIOTLB buffer");

}



int set_memory_encrypted(unsigned long addr, int numpages)

{

	if (!PAGE_ALIGNED(addr))

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