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) --- drivers/firmware/efi/efi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 111e87a618e5..56e9d73412fa 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -692,13 +692,13 @@ static __init int match_config_table(const efi_guid_t *guid, static __init void reserve_unaccepted(struct efi_unaccepted_memory *unaccepted) { - phys_addr_t start, size; + phys_addr_t start, end; start = PAGE_ALIGN_DOWN(efi.unaccepted); - size = PAGE_ALIGN(sizeof(*unaccepted) + unaccepted->size); + end = PAGE_ALIGN(efi.unaccepted + sizeof(*unaccepted) + unaccepted->size); - memblock_add(start, size); - memblock_reserve(start, size); + memblock_add(start, end - start); + memblock_reserve(start, end - start); } int __init efi_config_parse_tables(const efi_config_table_t *config_tables, -- 2.51.2 The accept_memory() and range_contains_unaccepted_memory() functions employ a "guard page" logic to prevent crashes with load_unaligned_zeropad(). This logic extends the range to be accepted (or checked) by one unit_size if the end of the range is aligned to a unit_size boundary. However, if the caller passes a range that is not page-aligned, the 'end' of the range might not be numerically aligned to unit_size, even if it covers the last page of a unit. This causes the "if (!(end % unit_size))" check to fail, skipping the necessary extension and leaving the next unit unaccepted, which can lead to a kernel panic when accessed by load_unaligned_zeropad(). Align the start address down and the size up to the nearest page boundary before performing the unit_size alignment check. This ensures that the guard unit is correctly added when the range effectively ends on a unit boundary. Signed-off-by: Kiryl Shutsemau (Meta) --- drivers/firmware/efi/unaccepted_memory.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c index c2c067eff634..9ddf3dedd514 100644 --- a/drivers/firmware/efi/unaccepted_memory.c +++ b/drivers/firmware/efi/unaccepted_memory.c @@ -35,14 +35,18 @@ void accept_memory(phys_addr_t start, unsigned long size) struct efi_unaccepted_memory *unaccepted; unsigned long range_start, range_end; struct accept_range range, *entry; - phys_addr_t end = start + size; unsigned long flags; + phys_addr_t end; u64 unit_size; unaccepted = efi_get_unaccepted_table(); if (!unaccepted) return; + start = PAGE_ALIGN_DOWN(start); + size = PAGE_ALIGN(size); + end = start + size; + unit_size = unaccepted->unit_size; /* @@ -160,15 +164,19 @@ void accept_memory(phys_addr_t start, unsigned long size) bool range_contains_unaccepted_memory(phys_addr_t start, unsigned long size) { struct efi_unaccepted_memory *unaccepted; - phys_addr_t end = start + size; unsigned long flags; bool ret = false; + phys_addr_t end; u64 unit_size; unaccepted = efi_get_unaccepted_table(); if (!unaccepted) return false; + start = PAGE_ALIGN_DOWN(start); + size = PAGE_ALIGN(size); + end = start + size; + unit_size = unaccepted->unit_size; /* -- 2.51.2