Re: [PATCH V8] acpi/prmt: find block with specific type

[Koba Ko]

On 10/13/24 03:36, Ard Biesheuvel wrote:
> External email: Use caution opening links or attachments
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>
> On Sat, 12 Oct 2024 at 21:16, KobaK <kobak@xxxxxxxxxx> wrote:
> > From: Koba Ko <kobak@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxxx
> > Signed-off-by: Koba Ko <kobak@xxxxxxxxxx>
> > Reviewed-by: Matthew R. Ochs <mochs@xxxxxxxxxx>
> > Reviewed-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> > Reviewed-by: Ard Biesheuvel <ardb@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
> > 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
> 'fix 0day' means nothing - please describe what the actual change is
> compared to the previous version.
Thanks, will do it in v9
> > ---
> >   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..552442bc10fd 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, (void *)pa);
> > +
> 'pa' is not a pointer so don't treat it as one - please drop the cast,
> and use 0x%llx as the format specifier.