linux-kernel - [tip: x86/urgent] x86/ioremap: Map EFI-reserved memory as encrypted for SEV

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Date:   Tue, 08 Jun 2021 15:26:59 -0000
From:   "tip-bot2 for Tom Lendacky" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Borislav Petkov <bp@...e.de>, <stable@...r.kernel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/ioremap: Map EFI-reserved memory as encrypted for SEV

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b
Gitweb:        https://git.kernel.org/tip/8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b
Author:        Tom Lendacky <thomas.lendacky@....com>
AuthorDate:    Tue, 08 Jun 2021 11:54:33 +02:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Tue, 08 Jun 2021 16:26:55 +02:00

x86/ioremap: Map EFI-reserved memory as encrypted for SEV

Some drivers require memory that is marked as EFI boot services
data. In order for this memory to not be re-used by the kernel
after ExitBootServices(), efi_mem_reserve() is used to preserve it
by inserting a new EFI memory descriptor and marking it with the
EFI_MEMORY_RUNTIME attribute.

Under SEV, memory marked with the EFI_MEMORY_RUNTIME attribute needs to
be mapped encrypted by Linux, otherwise the kernel might crash at boot
like below:

  EFI Variables Facility v0.08 2004-May-17
  general protection fault, probably for non-canonical address 0x3597688770a868b2: 0000 [#1] SMP NOPTI
  CPU: 13 PID: 1 Comm: swapper/0 Not tainted 5.12.4-2-default #1 openSUSE Tumbleweed
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:efi_mokvar_entry_next
  [...]
  Call Trace:
   efi_mokvar_sysfs_init
   ? efi_mokvar_table_init
   do_one_initcall
   ? __kmalloc
   kernel_init_freeable
   ? rest_init
   kernel_init
   ret_from_fork

Expand the __ioremap_check_other() function to additionally check for
this other type of boot data reserved at runtime and indicate that it
should be mapped encrypted for an SEV guest.

 [ bp: Massage commit message. ]

Fixes: 58c909022a5a ("efi: Support for MOK variable config table")
Reported-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Tested-by: Joerg Roedel <jroedel@...e.de>
Cc: <stable@...r.kernel.org> # 5.10+
Link: https://lkml.kernel.org/r/20210608095439.12668-2-joro@8bytes.org
---
 arch/x86/mm/ioremap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 12c686c..60ade7d 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -118,7 +118,9 @@ static void __ioremap_check_other(resource_size_t addr, struct ioremap_desc *des
 	if (!IS_ENABLED(CONFIG_EFI))
 		return;
 
-	if (efi_mem_type(addr) == EFI_RUNTIME_SERVICES_DATA)
+	if (efi_mem_type(addr) == EFI_RUNTIME_SERVICES_DATA ||
+	    (efi_mem_type(addr) == EFI_BOOT_SERVICES_DATA &&
+	     efi_mem_attributes(addr) & EFI_MEMORY_RUNTIME))
 		desc->flags |= IORES_MAP_ENCRYPTED;
 }