kernel.git/drivers/firmware/efi/efi.c, branch linux-5.18.y

efi: Allow to enable EFI runtime services by default on RT

2022-06-09T08:29:58Z

[ Upstream commit a031651ff2144a3d81d4916856c093bc1ea0a413 ] Commit d9f283ae71af ("efi: Disable runtime services on RT") disabled EFI runtime services by default when the CONFIG_PREEMPT_RT option is enabled. The rationale for that commit is that some EFI calls could take too much time, leading to large latencies which is an issue for Real-Time kernels. But a side effect of that change was that now is not possible anymore to enable the EFI runtime services by default when CONFIG_PREEMPT_RT is set, without passing an efi=runtime command line parameter to the kernel. Instead, let's add a new EFI_DISABLE_RUNTIME boolean Kconfig option, that would be set to n by default but to y if CONFIG_PREEMPT_RT is enabled. That way, the current behaviour is preserved but gives users a mechanism to enable the EFI runtimes services in their kernels if that is required. For example, if the firmware could guarantee bounded time for EFI calls. Also, having a separate boolean config could allow users to disable the EFI runtime services by default even when CONFIG_PREEMPT_RT is not set. Reported-by: Alexander Larsson Fixes: d9f283ae71af ("efi: Disable runtime services on RT") Signed-off-by: Javier Martinez Canillas Link: https://lore.kernel.org/r/20220331151654.184433-1-javierm@redhat.com Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi: fix return value of __setup handlers

2022-03-01T08:02:21Z

When "dump_apple_properties" is used on the kernel boot command line, it causes an Unknown parameter message and the string is added to init's argument strings: Unknown kernel command line parameters "dump_apple_properties BOOT_IMAGE=/boot/bzImage-517rc6 efivar_ssdt=newcpu_ssdt", will be passed to user space. Run /sbin/init as init process with arguments: /sbin/init dump_apple_properties with environment: HOME=/ TERM=linux BOOT_IMAGE=/boot/bzImage-517rc6 efivar_ssdt=newcpu_ssdt Similarly when "efivar_ssdt=somestring" is used, it is added to the Unknown parameter message and to init's environment strings, polluting them (see examples above). Change the return value of the __setup functions to 1 to indicate that the __setup options have been handled. Fixes: 58c5475aba67 ("x86/efi: Retrieve and assign Apple device properties") Fixes: 475fb4e8b2f4 ("efi / ACPI: load SSTDs from EFI variables") Signed-off-by: Randy Dunlap Reported-by: Igor Zhbanov Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Cc: Ard Biesheuvel Cc: linux-efi@vger.kernel.org Cc: Lukas Wunner Cc: Octavian Purdila Cc: "Rafael J. Wysocki" Cc: Matt Fleming Link: https://lore.kernel.org/r/20220301041851.12459-1-rdunlap@infradead.org Signed-off-by: Ard Biesheuvel

efi: runtime: avoid EFIv2 runtime services on Apple x86 machines

2022-01-23T09:31:27Z

Aditya reports [0] that his recent MacbookPro crashes in the firmware when using the variable services at runtime. The culprit appears to be a call to QueryVariableInfo(), which we did not use to call on Apple x86 machines in the past as they only upgraded from EFI v1.10 to EFI v2.40 firmware fairly recently, and QueryVariableInfo() (along with UpdateCapsule() et al) was added in EFI v2.00. The only runtime service introduced in EFI v2.00 that we actually use in Linux is QueryVariableInfo(), as the capsule based ones are optional, generally not used at runtime (all the LVFS/fwupd firmware update infrastructure uses helper EFI programs that invoke capsule update at boot time, not runtime), and not implemented by Apple machines in the first place. QueryVariableInfo() is used to 'safely' set variables, i.e., only when there is enough space. This prevents machines with buggy firmwares from corrupting their NVRAMs when they run out of space. Given that Apple machines have been using EFI v1.10 services only for the longest time (the EFI v2.0 spec was released in 2006, and Linux support for the newly introduced runtime services was added in 2011, but the MacbookPro12,1 released in 2015 still claims to be EFI v1.10 only), let's avoid the EFI v2.0 ones on all Apple x86 machines. [0] https://lore.kernel.org/all/6D757C75-65B1-468B-842D-10410081A8E4@live.com/ Cc: Cc: Jeremy Kerr Cc: Matthew Garrett Reported-by: Aditya Garg Tested-by: Orlando Chamberlain Signed-off-by: Ard Biesheuvel Tested-by: Aditya Garg Link: https://bugzilla.kernel.org/show_bug.cgi?id=215277

efi: Allow efi=runtime

2021-09-28T20:44:15Z

In case the command line option "efi=noruntime" is default at built-time, the user could overwrite its state by `efi=runtime' and allow it again. This is useful on PREEMPT_RT where "efi=noruntime" is default and the user might need to alter the boot order for instance. Acked-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Ard Biesheuvel

efi: Disable runtime services on RT

2021-09-28T20:43:53Z

Based on measurements the EFI functions get_variable / get_next_variable take up to 2us which looks okay. The functions get_time, set_time take around 10ms. These 10ms are too much. Even one ms would be too much. Ard mentioned that SetVariable might even trigger larger latencies if the firmware will erase flash blocks on NOR. The time-functions are used by efi-rtc and can be triggered during run-time (either via explicit read/write or ntp sync). The variable write could be used by pstore. These functions can be disabled without much of a loss. The poweroff / reboot hooks may be provided by PSCI. Disable EFI's runtime wrappers on PREEMPT_RT. This was observed on "EFI v2.60 by SoftIron Overdrive 1000". Acked-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Ard Biesheuvel

firmware/efi: Tell memblock about EFI iomem reservations

2021-07-16T16:05:49Z

kexec_load_file() relies on the memblock infrastructure to avoid stamping over regions of memory that are essential to the survival of the system. However, nobody seems to agree how to flag these regions as reserved, and (for example) EFI only publishes its reservations in /proc/iomem for the benefit of the traditional, userspace based kexec tool. On arm64 platforms with GICv3, this can result in the payload being placed at the location of the LPI tables. Shock, horror! Let's augment the EFI reservation code with a memblock_reserve() call, protecting our dear tables from the secondary kernel invasion. Reported-by: Moritz Fischer Tested-by: Moritz Fischer Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Cc: Ard Biesheuvel Cc: James Morse Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Ard Biesheuvel

firmware/efi: Fix a use after bug in efi_mem_reserve_persistent

2021-03-19T06:44:27Z

In the for loop in efi_mem_reserve_persistent(), prsv = rsv->next use the unmapped rsv. Use the unmapped pages will cause segment fault. Fixes: 18df7577adae6 ("efi/memreserve: deal with memreserve entries in unmapped memory") Signed-off-by: Lv Yunlong Signed-off-by: Ard Biesheuvel

mm/gup: prevent gup_fast from racing with COW during fork

2020-12-15T20:13:39Z

Since commit 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes") pages under a FOLL_PIN will not be write protected during COW for fork. This means that pages returned from pin_user_pages(FOLL_WRITE) should not become write protected while the pin is active. However, there is a small race where get_user_pages_fast(FOLL_PIN) can establish a FOLL_PIN at the same time copy_present_page() is write protecting it: CPU 0 CPU 1 get_user_pages_fast() internal_get_user_pages_fast() copy_page_range() pte_alloc_map_lock() copy_present_page() atomic_read(has_pinned) == 0 page_maybe_dma_pinned() == false atomic_set(has_pinned, 1); gup_pgd_range() gup_pte_range() pte_t pte = gup_get_pte(ptep) pte_access_permitted(pte) try_grab_compound_head() pte = pte_wrprotect(pte) set_pte_at(); pte_unmap_unlock() // GUP now returns with a write protected page The first attempt to resolve this by using the write protect caused problems (and was missing a barrrier), see commit f3c64eda3e50 ("mm: avoid early COW write protect games during fork()") Instead wrap copy_p4d_range() with the write side of a seqcount and check the read side around gup_pgd_range(). If there is a collision then get_user_pages_fast() fails and falls back to slow GUP. Slow GUP is safe against this race because copy_page_range() is only called while holding the exclusive side of the mmap_lock on the src mm_struct. [akpm@linux-foundation.org: coding style fixes] Link: https://lore.kernel.org/r/CAHk-=wi=iCnYCARbPGjkVJu9eyYeZ13N64tZYLdOB8CP5Q_PLw@mail.gmail.com Link: https://lkml.kernel.org/r/2-v4-908497cf359a+4782-gup_fork_jgg@nvidia.com Fixes: f3c64eda3e50 ("mm: avoid early COW write protect games during fork()") Signed-off-by: Jason Gunthorpe Suggested-by: Linus Torvalds Reviewed-by: John Hubbard Reviewed-by: Jan Kara Reviewed-by: Peter Xu Acked-by: "Ahmed S. Darwish" [seqcount_t parts] Cc: Andrea Arcangeli Cc: "Aneesh Kumar K.V" Cc: Christoph Hellwig Cc: Hugh Dickins Cc: Jann Horn Cc: Kirill Shutemov Cc: Kirill Tkhai Cc: Leon Romanovsky Cc: Michal Hocko Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

efi/efivars: Set generic ops before loading SSDT

2020-11-25T15:55:02Z

Efivars allows for overriding of SSDT tables, however starting with commit bf67fad19e493b ("efi: Use more granular check for availability for variable services") this use case is broken. When loading SSDT generic ops should be set first, however mentioned commit reversed order of operations. Fix this by restoring original order of operations. Fixes: bf67fad19e493b ("efi: Use more granular check for availability for variable services") Signed-off-by: Amadeusz Sławiński Link: https://lore.kernel.org/r/20201123172817.124146-1-amadeuszx.slawinski@linux.intel.com Tested-by: Cezary Rojewski Signed-off-by: Ard Biesheuvel

Merge branch 'efi/urgent' into efi/core, to pick up fixes

2020-10-12T11:38:31Z

These fixes missed the v5.9 merge window, pick them up for early v5.10 merge. Signed-off-by: Ingo Molnar