From 9aa6ea69852c46e551f4180dce4208bd53df418c Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 6 Apr 2022 02:29:34 +0300 Subject: [PATCH] x86/tdx: Make pages shared in ioremap() In TDX guests, guest memory is protected from host access. If a guest performs I/O, it needs to explicitly share the I/O memory with the host. Make all ioremap()ed pages that are not backed by normal memory (IORES_DESC_NONE or IORES_DESC_RESERVED) mapped as shared. The permissions in PAGE_KERNEL_IO already work for "decrypted" memory on AMD SEV/SME systems. That means that they have no need to make a pgprot_decrypted() call. TDX guests, on the other hand, _need_ change to PAGE_KERNEL_IO for "decrypted" mappings. Add a pgprot_decrypted() for TDX. Co-developed-by: Kuppuswamy Sathyanarayanan Signed-off-by: Kuppuswamy Sathyanarayanan Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Reviewed-by: Andi Kleen Reviewed-by: Tony Luck Reviewed-by: Dave Hansen Reviewed-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20220405232939.73860-26-kirill.shutemov@linux.intel.com --- arch/x86/mm/ioremap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 17a492c..1ad0228 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -242,10 +242,15 @@ __ioremap_caller(resource_size_t phys_addr, unsigned long size, * If the page being mapped is in memory and SEV is active then * make sure the memory encryption attribute is enabled in the * resulting mapping. + * In TDX guests, memory is marked private by default. If encryption + * is not requested (using encrypted), explicitly set decrypt + * attribute in all IOREMAPPED memory. */ prot = PAGE_KERNEL_IO; if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted) prot = pgprot_encrypted(prot); + else + prot = pgprot_decrypted(prot); switch (pcm) { case _PAGE_CACHE_MODE_UC: -- 2.7.4