Re: [PATCH V7] acpi/prmt: find block with specific type

Koba Ko
2024-10-09T06:51:53Z

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@nvidia.com> wrote:
>> From: kobak <kobak@nvidia.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@nvidia.com>
>> Reviewed-by: Matthew R. Ochs <mochs@nvidia.com>
>> Reviewed-by: Zhang Rui <rui.zhang@intel.com>
> Reviewed-by: Ard Biesheuvel <ardb@kernel.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
>>