[PATCH 5.12 142/178] x86/ioremap: Map EFI-reserved memory as encrypted for SEV

Greg Kroah-Hartman
2021-06-21T16:48:53Z

From: Tom Lendacky <thomas.lendacky@amd.com>

commit 8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b upstream.

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@suse.de>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Joerg Roedel <jroedel@suse.de>
Cc: <stable@vger.kernel.org> # 5.10+
Link: https://lkml.kernel.org/r/20210608095439.12668-2-joro@8bytes.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/mm/ioremap.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -118,7 +118,9 @@ static void __ioremap_check_other(resour
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;
}