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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
This commit is contained in:
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
View File

@ -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 */

6
arch/powerpc/mm/mem.c
View File

@ -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);

26
arch/powerpc/platforms/pseries/svm.c
View File

@ -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))