linux-kernel - Re: [PATCH V9] acpi/prmt: find block with specific type

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Message-ID: <6a08b06b-5672-473a-9a0a-7068da5db0d1@nvidia.com>
Date: Sun, 13 Oct 2024 03:49:56 +0800
From: Koba Ko <kobak@...dia.com>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: Matt Ochs <mochs@...dia.com>, James Morse <james.morse@....com>,
 "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
 Zhang Rui <rui.zhang@...el.com>, linux-efi@...r.kernel.org
Subject: Re: [PATCH V9] acpi/prmt: find block with specific type


On 10/13/24 03:46, Ard Biesheuvel wrote:
> External email: Use caution opening links or attachments
>
>
> On Sat, 12 Oct 2024 at 21:42, KobaK <kobak@...dia.com> wrote:
>> From: Koba Ko <kobak@...dia.com>
>>
>> PRMT needs to find the correct type of block to
>> translate the PA-VA mapping for EFI runtime services.
>>
>> The issue arises because the PRMT is finding a block of
>> type EFI_CONVENTIONAL_MEMORY, which is not appropriate for
>> runtime services as described in Section 2.2.2 (Runtime
>> Services) of the UEFI Specification [1]. Since the PRM handler is
>> a type of runtime service, this causes an exception
>> when the PRM handler is called.
>>
>>      [Firmware Bug]: Unable to handle paging request in EFI runtime service
>>      WARNING: CPU: 22 PID: 4330 at drivers/firmware/efi/runtime-wrappers.c:341
>>          __efi_queue_work+0x11c/0x170
>>      Call trace:
>>
>> Find a block with specific type to fix this.
>> PRMT find a block with EFI_MEMORY_RUNTIME for PRM handler and PRM context.
>> If no suitable block is found, a warning message will be prompted
>> but the procedure continues to manage the next PRM handler.
>> However, if the PRM handler is actually called without proper allocation,
>> it would result in a failure during error handling.
>>
>> By using the correct memory types for runtime services,
>> ensure that the PRM handler and the context are
>> properly mapped in the virtual address space during runtime,
>> preventing the paging request error.
>>
>> The issue is really that only memory that has been remapped for
>> runtime by the firmware can be used by the PRM handler, and so the
>> region needs to have the EFI_MEMORY_RUNTIME attribute.
>>
>> [1] https://uefi.org/sites/default/files/resources/UEFI_Spec_2_10_Aug29.pdf
>> Fixes: cefc7ca46235 ("ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype")
>> cc: stable@...r.kernel.org
>> Signed-off-by: Koba Ko <kobak@...dia.com>
>> Reviewed-by: Matthew R. Ochs <mochs@...dia.com>
>> Reviewed-by: Zhang Rui <rui.zhang@...el.com>
>> Reviewed-by: Ard Biesheuvel <ardb@...nel.org>
>> ---
>> V2:
>> 1. format the changelog and add more about error handling.
>> 2. replace goto
>> V3: Warn if parts of handler are missed during va-pa translating.
>> V4: Fix the 0day
>> V5: Fix typo and pr_warn warning
>> V6: use EFI_MOMOERY_RUNTIME to find block and split goto refactor as a single
>> patch
>> V7:
>> 1. refine the codes and commit description as per comments
>> 2. drop goto refacotr
>> V8: Fix 0day and cc to stable
>> V9: Describe 0day fix
>> cast PA as (void *) in pr_warn
> Sigh.
>
> Please read to the end of my previous email and fix the other thing too.
Sorry, I lost that.