lkml.org 
[lkml]   [2022]   [Apr]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: x86/tdx] x86/tdx: Make pages shared in ioremap()
The following commit has been merged into the x86/tdx branch of tip:

Commit-ID: 9aa6ea69852c46e551f4180dce4208bd53df418c
Gitweb: https://git.kernel.org/tip/9aa6ea69852c46e551f4180dce4208bd53df418c
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
AuthorDate: Wed, 06 Apr 2022 02:29:34 +03:00
Committer: Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Thu, 07 Apr 2022 08:27:53 -07:00

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
---
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:
\
 
 \ /
  Last update: 2022-04-09 03:28    [W:0.509 / U:0.144 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site