This is a note to let you know that I've just added the patch titled ACPI: PRM: Check whether EFI runtime is available to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: acpi-prm-check-whether-efi-runtime-is-available.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 182da6f2b81a78709c58021542fb694f8ed80774 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel <ardb@xxxxxxxxxx> Date: Thu, 12 Jan 2023 14:33:19 +0100 Subject: ACPI: PRM: Check whether EFI runtime is available From: Ard Biesheuvel <ardb@xxxxxxxxxx> commit 182da6f2b81a78709c58021542fb694f8ed80774 upstream. The ACPI PRM address space handler calls efi_call_virt_pointer() to execute PRM firmware code, but doing so is only permitted when the EFI runtime environment is available. Otherwise, such calls are guaranteed to result in a crash, and must therefore be avoided. Given that the EFI runtime services may become unavailable after a crash occurring in the firmware, we need to check this each time the PRM address space handler is invoked. If the EFI runtime services were not available at registration time to being with, don't install the address space handler at all. Fixes: cefc7ca46235 ("ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype") Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> Cc: All applicable <stable@xxxxxxxxxxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/acpi/prmt.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/drivers/acpi/prmt.c +++ b/drivers/acpi/prmt.c @@ -236,6 +236,11 @@ static acpi_status acpi_platformrt_space efi_status_t status; struct prm_context_buffer context; + if (!efi_enabled(EFI_RUNTIME_SERVICES)) { + pr_err_ratelimited("PRM: EFI runtime services no longer available\n"); + return AE_NO_HANDLER; + } + /* * The returned acpi_status will always be AE_OK. Error values will be * saved in the first byte of the PRM message buffer to be used by ASL. @@ -325,6 +330,11 @@ void __init init_prmt(void) pr_info("PRM: found %u modules\n", mc); + if (!efi_enabled(EFI_RUNTIME_SERVICES)) { + pr_err("PRM: EFI runtime services unavailable\n"); + return; + } + status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT, ACPI_ADR_SPACE_PLATFORM_RT, &acpi_platformrt_space_handler, Patches currently in stable-queue which might be from ardb@xxxxxxxxxx are queue-6.1/acpi-prm-check-whether-efi-runtime-is-available.patch