Commit dfcf2e01 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Christoph Hellwig
Browse files

swiotlb: do not zero buffer in set_memory_decrypted() 



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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 0280e3c5

kernel/dma/swiotlb.c

+0 −2
Original line number Diff line number Diff line
@@ -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,