linux_dsm_epyc7002/drivers/firmware/efi
Sai Praneeth 3eb420e70d efi: Use a work queue to invoke EFI Runtime Services
Presently, when a user process requests the kernel to execute any
UEFI runtime service, the kernel temporarily switches to a separate
set of page tables that describe the virtual mapping of the UEFI
runtime services regions in memory. Since UEFI runtime services are
typically invoked with interrupts enabled, any code that may be called
during this time, will have an incorrect view of the process's address
space. Although it is unusual for code running in interrupt context to
make assumptions about the process context it runs in, there are cases
(such as the perf subsystem taking samples) where this causes problems.

So let's set up a work queue for calling UEFI runtime services, so that
the actual calls are made when the work queue items are dispatched by a
work queue worker running in a separate kernel thread. Such threads are
not expected to have userland mappings in the first place, and so the
additional mappings created for the UEFI runtime services can never
clash with any.

The ResetSystem() runtime service is not covered by the work queue
handling, since it is not expected to return, and may be called at a
time when the kernel is torn down to the point where we cannot expect
work queues to still be operational.

The non-blocking variants of SetVariable() and QueryVariableInfo()
are also excluded: these are intended to be used from atomic context,
which obviously rules out waiting for a completion to be signalled by
another thread. Note that these variants are currently only used for
UEFI runtime services calls that occur very early in the boot, and
for ones that occur in critical conditions, e.g., to flush kernel logs
to UEFI variables via efi-pstore.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
[ardb: exclude ResetSystem() from the workqueue treatment
       merge from 2 separate patches and rewrite commit log]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180711094040.12506-4-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 00:43:12 +02:00
..
libstub efi/libstub/tpm: Initialize efi_physical_addr_t vars to zero for mixed mode 2018-06-22 10:58:27 +02:00
test License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
apple-properties.c device property: Get rid of union aliasing 2018-05-17 12:47:21 +02:00
arm-init.c treewide: use PHYS_ADDR_MAX to avoid type casting ULLONG_MAX 2018-06-15 07:55:25 +09:00
arm-runtime.c efi: Use efi_mm in x86 as well as ARM 2018-03-12 10:05:01 +01:00
capsule-loader.c efi/capsule-loader: Don't output reset log when reset flags are not set 2018-05-14 08:57:49 +02:00
capsule.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
cper-arm.c efi/cper: Remove the INDENT_SP silliness 2018-05-14 08:57:47 +02:00
cper-x86.c efi: Decode IA32/X64 Context Info structure 2018-05-14 08:57:48 +02:00
cper.c efi: Decode IA32/X64 Processor Error Section 2018-05-14 08:57:47 +02:00
dev-path-parser.c efi: Add device path parser 2016-11-13 08:23:15 +01:00
efi-bgrt.c efi/bgrt: Use efi_mem_type() 2017-08-26 09:20:33 +02:00
efi-pstore.c pstore: Convert internal records to timespec64 2018-06-05 16:57:31 -07:00
efi.c efi: Use a work queue to invoke EFI Runtime Services 2018-07-16 00:43:12 +02:00
efibc.c efibc: Report more information in the error messages 2016-06-27 13:06:54 +02:00
efivars.c efi: Don't use spinlocks for efi vars 2016-09-09 16:08:42 +01:00
esrt.c efi/esrt: Fix handling of early ESRT table mapping 2018-03-12 10:05:01 +01:00
fake_mem.c x86/efi: Don't allocate memmap through memblock after mm_init() 2017-01-07 08:58:07 +01:00
Kconfig efi: Decode IA32/X64 Processor Error Section 2018-05-14 08:57:47 +02:00
Makefile efi: Decode IA32/X64 Processor Error Section 2018-05-14 08:57:47 +02:00
memattr.c x86/efi: Add support for EFI_MEMORY_ATTRIBUTES_TABLE 2017-02-01 08:45:44 +01:00
memmap.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
runtime-map.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
runtime-wrappers.c efi: Use a work queue to invoke EFI Runtime Services 2018-07-16 00:43:12 +02:00
tpm.c efi: call get_event_log before ExitBootServices 2018-01-08 12:58:35 +02:00
vars.c efi: Don't use spinlocks for efi vars 2016-09-09 16:08:42 +01:00