(Cc the correct arm mailing list) On Thu, Feb 15, 2024 at 02:51:06PM -0800, Boqun Feng wrote: > Currently ACPI_MEMORY_NVS is omitted from the linear map, which causes > a trouble with the following firmware memory region setup: > > [..] efi: 0x0000dfd62000-0x0000dfd83fff [ACPI Reclaim|...] > [..] efi: 0x0000dfd84000-0x0000dfd87fff [ACPI Mem NVS|...] > > , on ARM64 with 64k page size, the whole 0x0000dfd80000-0x0000dfd8ffff > range will be omitted from the the linear map due to 64k round-up. And > a page fault happens when trying to access the ACPI_RECLAIM_MEMORY: > > [...] Unable to handle kernel paging request at virtual address ffff0000dfd80000 > > To fix this, add ACPI_MEMORY_NVS into the linear map. > > Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx # 5.15+ > --- > We hit this in an ARM64 Hyper-V VM when using 64k page size, although > this issue may also be fixed if the efi memory regions are all 64k > aligned, but I don't find this memory region setup is invalid per UEFI > spec, also I don't find that spec disallows ACPI_MEMORY_NVS to be mapped > in the OS linear map, but if there is any better way or I'm reading the > spec incorrectly, please let me know. > > It's Cced stable since 5.15 because that's when Hyper-V ARM64 support is > added, and Hyper-V is the only one that hits the problem so far. > > drivers/firmware/efi/efi-init.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/firmware/efi/efi-init.c b/drivers/firmware/efi/efi-init.c > index a00e07b853f2..9a1b9bc66d50 100644 > --- a/drivers/firmware/efi/efi-init.c > +++ b/drivers/firmware/efi/efi-init.c > @@ -139,6 +139,7 @@ static __init int is_usable_memory(efi_memory_desc_t *md) > case EFI_LOADER_CODE: > case EFI_LOADER_DATA: > case EFI_ACPI_RECLAIM_MEMORY: > + case EFI_ACPI_MEMORY_NVS: > case EFI_BOOT_SERVICES_CODE: > case EFI_BOOT_SERVICES_DATA: > case EFI_CONVENTIONAL_MEMORY: > @@ -202,8 +203,12 @@ static __init void reserve_regions(void) > if (!is_usable_memory(md)) > memblock_mark_nomap(paddr, size); > > - /* keep ACPI reclaim memory intact for kexec etc. */ > - if (md->type == EFI_ACPI_RECLAIM_MEMORY) > + /* > + * keep ACPI reclaim and NVS memory and intact for kexec > + * etc. > + */ > + if (md->type == EFI_ACPI_RECLAIM_MEMORY || > + md->type == EFI_ACPI_MEMORY_NVS) > memblock_reserve(paddr, size); > } > } > -- > 2.43.0 >
