Re: [PATCH V5] acpi/prmt: find block with specific type

From: Ard Biesheuvel
Date: Wed Oct 02 2024 - 17:12:07 EST

On Wed, 2 Oct 2024 at 20:06, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>
> On Wed, Sep 11, 2024 at 5:55 PM KobaK <kobak@xxxxxxxxxx> wrote:
> >
> > 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:
> > __efi_queue_work+0x11c/0x170
> > efi_call_acpi_prm_handler+0x68/0xd0
> > acpi_platformrt_space_handler+0x198/0x258
> > acpi_ev_address_space_dispatch+0x144/0x388
> > acpi_ex_access_region+0x9c/0x118
> > acpi_ex_write_serial_bus+0xc4/0x218
> > acpi_ex_write_data_to_field+0x168/0x218
> > acpi_ex_store_object_to_node+0x1a8/0x258
> > acpi_ex_store+0xec/0x330
> > acpi_ex_opcode_1A_1T_1R+0x15c/0x618
> > acpi_ds_exec_end_op+0x274/0x548
> > acpi_ps_parse_loop+0x10c/0x6b8
> > acpi_ps_parse_aml+0x140/0x3b0
> > acpi_ps_execute_method+0x12c/0x2a0
> > acpi_ns_evaluate+0x210/0x310
> > acpi_evaluate_object+0x178/0x358
> > acpi_proc_write+0x1a8/0x8a0 [acpi_call]
> > proc_reg_write+0xcc/0x150
> > vfs_write+0xd8/0x380
> > ksys_write+0x70/0x120
> > __arm64_sys_write+0x24/0x48
> > invoke_syscall.constprop.0+0x80/0xf8
> > do_el0_svc+0x50/0x110
> > el0_svc+0x48/0x1d0
> > el0t_64_sync_handler+0x15c/0x178
> > el0t_64_sync+0x1a8/0x1b0
> >
> > Find a block with specific type to fix this.
> > prmt find a block with EFI_RUNTIME_SERVICES_DATA for prm handler and
> > find a block with EFI_RUNTIME_SERVICES_CODE for prm context.
> > If no suitable block is found, a warning message will be prompted
> > but the procedue continues to manage the next prm handler.
> > However, if the prm handler is actullay 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.
> >
> > [1] https://uefi.org/sites/default/files/resources/UEFI_Spec_2_10_Aug29.pdf
>
> I need input from EFI people on this, so can you please resend the
> patch with a CC to linux-efi@xxxxxxxxxxxxxxx?
>
> > Fixes: cefc7ca46235 ("ACPI: PRM: implement OperationRegion handler for the PlatformRtMechanism subtype")
> > Signed-off-by: KobaK <kobak@xxxxxxxxxx>

Please use your full name.

> > Reviewed-by: Matthew R. Ochs <mochs@xxxxxxxxxx>
> > ---
> > 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
> > ---
> > drivers/acpi/prmt.c | 49 +++++++++++++++++++++++++++++++--------------
> > 1 file changed, 34 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/acpi/prmt.c b/drivers/acpi/prmt.c
> > index c78453c74ef5..cd4a7f5491d6 100644
> > --- a/drivers/acpi/prmt.c
> > +++ b/drivers/acpi/prmt.c
> > @@ -72,15 +72,17 @@ 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(u64 pa, u32 type)
> > {
> > 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->type == type) &&
> > + (md->phys_addr < pa && pa < md->phys_addr + PAGE_SIZE * md->num_pages)) {
> > return pa_offset + md->virt_addr + page - md->phys_addr;
> > + }
> > }
> >
> > return 0;
> > @@ -148,9 +150,18 @@ 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(handler_info->handler_address, EFI_RUNTIME_SERVICES_CODE);

Wouldn't it make more sense to test the EFI_MEMORY_RUNTIME attribute
rather than expecting/assuming a certain memory type in each case?
That attribute is precisely what controls whether or not a region has
been remapped into the firmware's page tables.

> > + th->static_data_buffer_addr =
> > + efi_pa_va_lookup(handler_info->static_data_buffer_address, EFI_RUNTIME_SERVICES_DATA);
> > + th->acpi_param_buffer_addr =
> > + efi_pa_va_lookup(handler_info->acpi_param_buffer_address, EFI_RUNTIME_SERVICES_DATA);
> > +
> > + if (!th->handler_addr || !th->static_data_buffer_addr || !th->acpi_param_buffer_addr)
> > + pr_warn(
> > + "Idx: %llu, Parts of handler(GUID: %pUL) are missed, handler_addr %p, data_addr %p, param_addr %p",

Please improve this diagnostic: 'are missed' is not very helpful.


> > + cur_handler, &th->guid, th->handler_addr,
> > + (void *)th->static_data_buffer_addr, (void *)th->acpi_param_buffer_addr);
> > } while (++cur_handler < tm->handler_count && (handler_info = get_next_handler(handler_info)));
> >
> > return 0;
> > @@ -250,8 +261,16 @@ static acpi_status acpi_platformrt_space_handler(u32 function,
> >
> > handler = find_prm_handler(&buffer->handler_guid);
> > module = find_prm_module(&buffer->handler_guid);
> > - if (!handler || !module)
> > - goto invalid_guid;
> > + if (!handler || !module) {
> > + buffer->prm_status = PRM_HANDLER_GUID_NOT_FOUND;
> > + return AE_OK;
> > + }
> > +
> > + 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;
> > @@ -274,8 +293,10 @@ static acpi_status acpi_platformrt_space_handler(u32 function,
> > case PRM_CMD_START_TRANSACTION:
> >
> > module = find_prm_module(&buffer->handler_guid);
> > - if (!module)
> > - goto invalid_guid;
> > + if (!module) {
> > + buffer->prm_status = PRM_HANDLER_GUID_NOT_FOUND;
> > + return AE_OK;
> > + }

What is the reason for this change, and the ones down below?

> >
> > if (module->updatable)
> > module->updatable = false;
> > @@ -286,8 +307,10 @@ static acpi_status acpi_platformrt_space_handler(u32 function,
> > case PRM_CMD_END_TRANSACTION:
> >
> > module = find_prm_module(&buffer->handler_guid);
> > - if (!module)
> > - goto invalid_guid;
> > + if (!module) {
> > + buffer->prm_status = PRM_HANDLER_GUID_NOT_FOUND;
> > + return AE_OK;
> > + }
> >
> > if (module->updatable)
> > buffer->prm_status = UPDATE_UNLOCK_WITHOUT_LOCK;
> > @@ -302,10 +325,6 @@ static acpi_status acpi_platformrt_space_handler(u32 function,
> > }
> >
> > return AE_OK;
> > -
> > -invalid_guid:
> > - buffer->prm_status = PRM_HANDLER_GUID_NOT_FOUND;
> > - return AE_OK;
> > }
> >
> > void __init init_prmt(void)
> > --
> > 2.43.0
> >
> >
>