Message-ID: <4bab6b13-6cf6-4393-b2e4-f196ed9c2795@nvidia.com>
Date: Wed, 9 Oct 2024 14:51:45 +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 V7] acpi/prmt: find block with specific type


On 10/9/24 14:50, Ard Biesheuvel wrote:
> External email: Use caution opening links or attachments
>
>
> On Wed, 9 Oct 2024 at 08:45, KobaK <kobak@...dia.com> wrote:
>> From: kobak <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")
>> 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>
>
> This needs a cc:stable too
Hi Ard, Rui
Thanks for reviewed.
>
>> ---
>> 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
>> ---
>>
>>   drivers/acpi/prmt.c | 27 ++++++++++++++++++++++-----
>>   1 file changed, 22 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
>> index 1cfaa5957ac4..51f5ae3d4350 100644
>> --- a/drivers/acpi/prmt.c
>> +++ b/drivers/acpi/prmt.c
>> @@ -72,17 +72,21 @@ struct prm_module_info {
>>          struct prm_handler_info handlers[] __counted_by(handler_count);
>>   };
>>
>> -static u64 efi_pa_va_lookup(u64 pa)
>> +static u64 efi_pa_va_lookup(efi_guid_t *guid, u64 pa)
>>   {
>>          efi_memory_desc_t *md;
>>          u64 pa_offset = pa & ~PAGE_MASK;
>>          u64 page = pa & PAGE_MASK;
>>
>>          for_each_efi_memory_desc(md) {
>> -               if (md->phys_addr < pa && pa < md->phys_addr + PAGE_SIZE * md->num_pages)
>> +               if ((md->attribute & EFI_MEMORY_RUNTIME) &&
>> +                   (md->phys_addr < pa && pa < md->phys_addr + PAGE_SIZE * md->num_pages)) {
>>                          return pa_offset + md->virt_addr + page - md->phys_addr;
>> +               }
>>          }
>>
>> +       pr_warn("Failed to find VA for GUID: %pUL, PA: %p", guid, pa);
>> +
>>          return 0;
>>   }
>>
>> @@ -148,9 +152,15 @@ acpi_parse_prmt(union acpi_subtable_headers *header, const unsigned long end)
>>                  th = &tm->handlers[cur_handler];
>>
>>                  guid_copy(&th->guid, (guid_t *)handler_info->handler_guid);
>> -               th->handler_addr = (void *)efi_pa_va_lookup(handler_info->handler_address);
>> -               th->static_data_buffer_addr = efi_pa_va_lookup(handler_info->static_data_buffer_address);
>> -               th->acpi_param_buffer_addr = efi_pa_va_lookup(handler_info->acpi_param_buffer_address);
>> +               th->handler_addr =
>> +                       (void *)efi_pa_va_lookup(&th->guid, handler_info->handler_address);
>> +
>> +               th->static_data_buffer_addr =
>> +                       efi_pa_va_lookup(&th->guid, handler_info->static_data_buffer_address);
>> +
>> +               th->acpi_param_buffer_addr =
>> +                       efi_pa_va_lookup(&th->guid, handler_info->acpi_param_buffer_address);
>> +
>>          } while (++cur_handler < tm->handler_count && (handler_info = get_next_handler(handler_info)));
>>
>>          return 0;
>> @@ -277,6 +287,13 @@ static acpi_status acpi_platformrt_space_handler(u32 function,
>>                  if (!handler || !module)
>>                          goto invalid_guid;
>>
>> +               if (!handler->handler_addr ||
>> +                   !handler->static_data_buffer_addr ||
>> +                   !handler->acpi_param_buffer_addr) {
>> +                       buffer->prm_status = PRM_HANDLER_ERROR;
>> +                       return AE_OK;
>> +               }
>> +
>>                  ACPI_COPY_NAMESEG(context.signature, "PRMC");
>>                  context.revision = 0x0;
>>                  context.reserved = 0x0;
>> --
>> 2.43.0
>>

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