[PATCH v2 4/4] swiotlb: Free tbl memory in swiotlb_exit()

From: Will Deacon
Date: Tue Jul 20 2021 - 09:41:45 EST


Although swiotlb_exit() frees the 'slots' metadata array referenced by
'io_tlb_default_mem', it leaves the underlying buffer pages allocated
despite no longer being usable.

Extend swiotlb_exit() to free the buffer pages as well as the slots
array.

Cc: Claire Chang <tientzu@xxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Tested-by: Claire Chang <tientzu@xxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
kernel/dma/swiotlb.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index b3c793ed9e64..87c40517e822 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -328,18 +328,27 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)

void __init swiotlb_exit(void)
{
- size_t size;
struct io_tlb_mem *mem = &io_tlb_default_mem;
+ unsigned long tbl_vaddr;
+ size_t tbl_size, slots_size;

if (!mem->nslabs)
return;

pr_info("tearing down default memory pool\n");
- size = array_size(sizeof(*mem->slots), mem->nslabs);
- if (mem->late_alloc)
- free_pages((unsigned long)mem->slots, get_order(size));
- else
- memblock_free_late(__pa(mem->slots), PAGE_ALIGN(size));
+ tbl_vaddr = (unsigned long)phys_to_virt(mem->start);
+ tbl_size = PAGE_ALIGN(mem->end - mem->start);
+ slots_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), mem->nslabs));
+
+ set_memory_encrypted(tbl_vaddr, tbl_size >> PAGE_SHIFT);
+ if (mem->late_alloc) {
+ free_pages(tbl_vaddr, get_order(tbl_size));
+ free_pages((unsigned long)mem->slots, get_order(slots_size));
+ } else {
+ memblock_free_late(mem->start, tbl_size);
+ memblock_free_late(__pa(mem->slots), slots_size);
+ }
+
memset(mem, 0, sizeof(*mem));
}

--
2.32.0.402.g57bb445576-goog