kernel/linux.git/drivers/firmware/efi, branch v6.18.21

x86/efi: defer freeing of boot services memory

2026-03-12T11:09:36+00:00

commit a4b0bf6a40f3c107c67a24fbc614510ef5719980 upstream. efi_free_boot_services() frees memory occupied by EFI_BOOT_SERVICES_CODE and EFI_BOOT_SERVICES_DATA using memblock_free_late(). There are two issue with that: memblock_free_late() should be used for memory allocated with memblock_alloc() while the memory reserved with memblock_reserve() should be freed with free_reserved_area(). More acutely, with CONFIG_DEFERRED_STRUCT_PAGE_INIT=y efi_free_boot_services() is called before deferred initialization of the memory map is complete. Benjamin Herrenschmidt reports that this causes a leak of ~140MB of RAM on EC2 t3a.nano instances which only have 512MB or RAM. If the freed memory resides in the areas that memory map for them is still uninitialized, they won't be actually freed because memblock_free_late() calls memblock_free_pages() and the latter skips uninitialized pages. Using free_reserved_area() at this point is also problematic because __free_page() accesses the buddy of the freed page and that again might end up in uninitialized part of the memory map. Delaying the entire efi_free_boot_services() could be problematic because in addition to freeing boot services memory it updates efi.memmap without any synchronization and that's undesirable late in boot when there is concurrency. More robust approach is to only defer freeing of the EFI boot services memory. Split efi_free_boot_services() in two. First efi_unmap_boot_services() collects ranges that should be freed into an array then efi_free_boot_services() later frees them after deferred init is complete. Link: https://lore.kernel.org/all/ec2aaef14783869b3be6e3c253b2dcbf67dbc12a.camel@kernel.crashing.org Fixes: 916f676f8dc0 ("x86, efi: Retain boot service code until after switching to virtual mode") Cc: Signed-off-by: Mike Rapoport (Microsoft) Reviewed-by: Benjamin Herrenschmidt Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

EFI/CPER: don't go past the ARM processor CPER record buffer

2026-03-04T12:19:35+00:00

[ Upstream commit eae21beecb95a3b69ee5c38a659f774e171d730e ] There's a logic inside GHES/CPER to detect if the section_length is too small, but it doesn't detect if it is too big. Currently, if the firmware receives an ARM processor CPER record stating that a section length is big, kernel will blindly trust section_length, producing a very long dump. For instance, a 67 bytes record with ERR_INFO_NUM set 46198 and section length set to 854918320 would dump a lot of data going a way past the firmware memory-mapped area. Fix it by adding a logic to prevent it to go past the buffer if ERR_INFO_NUM is too big, making it report instead: [Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 1 [Hardware Error]: event severity: recoverable [Hardware Error]: Error 0, type: recoverable [Hardware Error]: section_type: ARM processor error [Hardware Error]: MIDR: 0xff304b2f8476870a [Hardware Error]: section length: 854918320, CPER size: 67 [Hardware Error]: section length is too big [Hardware Error]: firmware-generated error record is incorrect [Hardware Error]: ERR_INFO_NUM is 46198 Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Ard Biesheuvel Reviewed-by: Hanjun Guo [ rjw: Subject and changelog tweaks ] Link: https://patch.msgid.link/41cd9f6b3ace3cdff7a5e864890849e4b1c58b63.1767871950.git.mchehab+huawei@kernel.org Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

EFI/CPER: don't dump the entire memory region

2026-03-04T12:19:35+00:00

[ Upstream commit 55cc6fe5716f678f06bcb95140882dfa684464ec ] The current logic at cper_print_fw_err() doesn't check if the error record length is big enough to handle offset. On a bad firmware, if the ofset is above the actual record, length -= offset will underflow, making it dump the entire memory. The end result can be: - the logic taking a lot of time dumping large regions of memory; - data disclosure due to the memory dumps; - an OOPS, if it tries to dump an unmapped memory region. Fix it by checking if the section length is too small before doing a hex dump. Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Ard Biesheuvel Reviewed-by: Hanjun Guo [ rjw: Subject tweaks ] Link: https://patch.msgid.link/1752b5ba63a3e2f148ddee813b36c996cc617e86.1767871950.git.mchehab+huawei@kernel.org Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

efi: Fix reservation of unaccepted memory table

2026-02-26T22:59:44+00:00

[ Upstream commit 0862438c90487e79822d5647f854977d50381505 ] The reserve_unaccepted() function incorrectly calculates the size of the memblock reservation for the unaccepted memory table. It aligns the size of the table, but fails to account for cases where the table's starting physical address (efi.unaccepted) is not page-aligned. If the table starts at an offset within a page and its end crosses into a subsequent page that the aligned size does not cover, the end of the table will not be reserved. This can lead to the table being overwritten or inaccessible, causing a kernel panic in accept_memory(). This issue was observed when starting Intel TDX VMs with specific memory sizes (e.g., > 64GB). Fix this by calculating the end address first (including the unaligned start) and then aligning it up, ensuring the entire range is covered by the reservation. Fixes: 8dbe33956d96 ("efi/unaccepted: Make sure unaccepted table is mapped") Reported-by: Moritz Sanft Signed-off-by: Kiryl Shutsemau (Meta) Reviewed-by: Tom Lendacky Acked-by: Mike Rapoport (Microsoft) Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/cper: Fix cper_bits_to_str buffer handling and return value

2026-01-23T10:21:12+00:00

commit d7f1b4bdc7108be1b178e1617b5f45c8918e88d7 upstream. The return value calculation was incorrect: `return len - buf_size;` Initially `len = buf_size`, then `len` decreases with each operation. This results in a negative return value on success. Fix by returning `buf_size - len` which correctly calculates the actual number of bytes written. Fixes: a976d790f494 ("efi/cper: Add a new helper function to print bitmasks") Signed-off-by: Morduan Zang Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

efi: Add missing static initializer for efi_mm::cpus_allowed_lock

2026-01-02T11:57:07+00:00

commit 40374d308e4e456048d83991e937f13fc8bda8bf upstream. Initialize the cpus_allowed_lock struct member of efi_mm. Cc: stable@vger.kernel.org Signed-off-by: Ard Biesheuvel Acked-by: Catalin Marinas Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman

efi/cper: align ARM CPER type with UEFI 2.9A/2.10 specs

2025-12-18T13:03:41+00:00

[ Upstream commit 96b010536ee020e716d28d9b359a4bcd18800aeb ] Up to UEFI spec 2.9, the type byte of CPER struct for ARM processor was defined simply as: Type at byte offset 4: - Cache error - TLB Error - Bus Error - Micro-architectural Error All other values are reserved Yet, there was no information about how this would be encoded. Spec 2.9A errata corrected it by defining: - Bit 1 - Cache Error - Bit 2 - TLB Error - Bit 3 - Bus Error - Bit 4 - Micro-architectural Error All other values are reserved That actually aligns with the values already defined on older versions at N.2.4.1. Generic Processor Error Section. Spec 2.10 also preserve the same encoding as 2.9A. Adjust CPER and GHES handling code for both generic and ARM processors to properly handle UEFI 2.9A and 2.10 encoding. Link: https://uefi.org/specs/UEFI/2.10/Apx_N_Common_Platform_Error_Record.html#arm-processor-error-information Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Borislav Petkov (AMD) Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/cper: Adjust infopfx size to accept an extra space

2025-12-18T13:03:41+00:00

[ Upstream commit 8ad2c72e21efb3dc76c5b14089fa7984cdd87898 ] Compiling with W=1 with werror enabled produces an error: drivers/firmware/efi/cper-arm.c: In function ‘cper_print_proc_arm’: drivers/firmware/efi/cper-arm.c:298:64: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=] 298 | snprintf(infopfx, sizeof(infopfx), "%s ", newpfx); | ^ drivers/firmware/efi/cper-arm.c:298:25: note: ‘snprintf’ output between 2 and 65 bytes into a destination of size 64 298 | snprintf(infopfx, sizeof(infopfx), "%s ", newpfx); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As the logic there adds an space at the end of infopx buffer. Add an extra space to avoid such warning. Signed-off-by: Mauro Carvalho Chehab Reviewed-by: Jonathan Cameron Acked-by: Borislav Petkov (AMD) Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/cper: Add a new helper function to print bitmasks

2025-12-18T13:03:41+00:00

[ Upstream commit a976d790f49499ccaa0f991788ad8ebf92e7fd5c ] Add a helper function to print a string with names associated to each bit field. A typical example is: const char * const bits[] = { "bit 3 name", "bit 4 name", "bit 5 name", }; char str[120]; unsigned int bitmask = BIT(3) | BIT(5); #define MASK GENMASK(5,3) cper_bits_to_str(str, sizeof(str), FIELD_GET(MASK, bitmask), bits, ARRAY_SIZE(bits)); The above code fills string "str" with "bit 3 name|bit 5 name". Reviewed-by: Jonathan Cameron Signed-off-by: Mauro Carvalho Chehab Acked-by: Borislav Petkov (AMD) Signed-off-by: Ard Biesheuvel Signed-off-by: Sasha Levin

efi/libstub: Fix page table access in 5-level to 4-level paging transition

2025-12-18T13:02:51+00:00

[ Upstream commit 84361123413efc84b06f3441c6c827b95d902732 ] When transitioning from 5-level to 4-level paging, the existing code incorrectly accesses page table entries by directly dereferencing CR3 and applying PAGE_MASK. This approach has several issues: - __native_read_cr3() returns the raw CR3 register value, which on x86_64 includes not just the physical address but also flags Bits above the physical address width of the system (i.e. above __PHYSICAL_MASK_SHIFT) are also not masked. - The pgd value is masked by PAGE_SIZE which doesn't take into account the higher bits such as _PAGE_BIT_NOPTISHADOW. Replace this with proper accessor functions: - native_read_cr3_pa(): Uses CR3_ADDR_MASK to additionally mask metadata out of CR3 (like SME or LAM bits). All remaining bits are real address bits or reserved and must be 0. - mask pgd value with PTE_PFN_MASK instead of PAGE_MASK, accounting for flags above bit 51 (_PAGE_BIT_NOPTISHADOW in particular). Bits below 51, but above the max physical address are reserved and must be 0. Fixes: cb1c9e02b0c1 ("x86/efistub: Perform 4/5 level paging switch from the stub") Reported-by: Michael van der Westhuizen Reported-by: Tobias Fleig Co-developed-by: Kiryl Shutsemau Signed-off-by: Kiryl Shutsemau Signed-off-by: Usama Arif Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Ard Biesheuvel Link: https://patch.msgid.link/20251103141002.2280812-3-usamaarif642@gmail.com Signed-off-by: Sasha Levin