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swiotlb: do not zero buffer in set_memory_decrypted()

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For larger TDX VM, memset() after set_memory_decrypted() in
swiotlb_update_mem_attributes() takes substantial portion of boot time.

Zeroing doesn't serve any functional purpose. Malicious VMM can mess
with decrypted/shared buffer at any point.

Remove the memset().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Kirill A. Shutemov 2022-01-25 16:20:01 +03:00 • committed by Christoph Hellwig
parent 0280e3c58f
commit dfcf2e017f
1 changed files with 0 additions and 2 deletions
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2
kernel/dma/swiotlb.c
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@ -207,8 +207,6 @@ void __init swiotlb_update_mem_attributes(void)
mem->vaddr = swiotlb_mem_remap(mem, bytes);
if (!mem->vaddr)
mem->vaddr = vaddr;
memset(mem->vaddr, 0, bytes);
}
static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,