Patch-mainline: v5.19-rc1
Git-commit: 9aa6ea69852c46e551f4180dce4208bd53df418c
References: jsc#PED-342
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
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 <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20220405232939.73860-26-kirill.shutemov@linux.intel.com
Signed-off-by: Juergen Gross <jgross@suse.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 17a492c27306..1ad0228f8ceb 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:
--
2.35.3