linux-kernel - [PATCH 5/5] swiotlb: Free tbl memory in swiotlb

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Date:   Mon, 19 Jul 2021 13:30:54 +0100
From:   Will Deacon <will@...nel.org>
To:     iommu@...ts.linux-foundation.org
Cc:     linux-kernel@...r.kernel.org, Will Deacon <will@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Claire Chang <tientzu@...omium.org>,
        Christoph Hellwig <hch@....de>,
        Robin Murphy <robin.murphy@....com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH 5/5] swiotlb: Free tbl memory in swiotlb_exit()

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@...omium.org>
Cc: Christoph Hellwig <hch@....de>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Tested-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Will Deacon <will@...nel.org>
---
 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