linux-kernel - Re: [PATCH] ACPI: OSL: Fix the memory mapping of an ACPI GAS that addresses a data structure

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Date:   Tue, 17 May 2022 20:25:55 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     James Liu <james.liu@....com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI: OSL: Fix the memory mapping of an ACPI GAS that
 addresses a data structure

On Tue, May 17, 2022 at 7:56 PM James Liu <james.liu@....com> wrote:
>
> Hi Rafael and all,
> Could you take a look into this patches? The mentioned bug blocks EINJ
> testing whenever a system firmware can correctly support GAS according
> to ACPI 6.4.

The kernel test robot reported an issue with it.  Have you seen that report?

> On Fri, Apr 01, 2022 at 05:28:40PM +0000, james.liu@....com wrote:
> > From: James Liu <james.liu@....com>
> >
> >     Modify acpi_os_map_generic_address and acpi_os_unmap_generic_address
> >     to handle a case that a GAS table (i.e., Table 5.1 in ACPI 6.4) is used
> >     to address a data structure; in this case, the GAS has the field of
> >     "Register Bit Width" equal to 0.
> >
> >     For example, "Injection Instruction Entry" (Table 18.25 in ACPI 6.4)
> >     has a RegisterRegion field that is a GAS that points to a data
> >     structure SET_ERROR_TYPE_WITH_ADDRESS (Table 18.30), which is required
> >     when using EINJ (Error Injection module).
> >
> >     This fix preserves a fairly sufficient memory space (i.e., page size)
> >     to store the data structure so as to prevent EINJ module from loading
> >     failure if platform firmware can support Injection Instruction Entry in
> >     an EINJ table.
> >
> > Signed-off-by: James Liu <james.liu@....com>
> > ---
> >  drivers/acpi/osl.c | 23 +++++++++++++++++++++--
> >  1 file changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> > index 45c5c0e45..ab2f584b1 100644
> > --- a/drivers/acpi/osl.c
> > +++ b/drivers/acpi/osl.c
> > @@ -457,9 +457,15 @@ void __iomem *acpi_os_map_generic_address(struct acpi_generic_address *gas)
> >       if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
> >               return NULL;
> >
> > +     /* Handle a case that GAS is used to address an ACPI data structure */
> > +     if (!gas->bit_width) {
> > +             pr_info("An ACPI data structure at 0x%llx is mapped\n", addr);
> > +             return  acpi_os_map_iomem(addr, PAGE_SIZE);
> > +     }
> > +
> >       /* Handle possible alignment issues */
> >       memcpy(&addr, &gas->address, sizeof(addr));
> > -     if (!addr || !gas->bit_width)
> > +     if (!addr)
> >               return NULL;
> >
> >       return acpi_os_map_iomem(addr, gas->bit_width / 8);
> > @@ -474,9 +480,22 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *gas)
> >       if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
> >               return;
> >
> > +     /* Handle a case that GAS is used to address an ACPI data structure */
> > +     if (!gas->bit_width) {
> > +             pr_info("An ACPI data structure at 0x%llx is unmapped\n", addr);
> > +             mutex_lock(&acpi_ioremap_lock);
> > +             map = acpi_map_lookup(addr, PAGE_SIZE);
> > +             if (!map) {
> > +                     mutex_unlock(&acpi_ioremap_lock);
> > +                     return;
> > +             }
> > +             acpi_os_drop_map_ref(map);
> > +             mutex_unlock(&acpi_ioremap_lock);
> > +     }
> > +
> >       /* Handle possible alignment issues */
> >       memcpy(&addr, &gas->address, sizeof(addr));
> > -     if (!addr || !gas->bit_width)
> > +     if (!addr)
> >               return;
> >
> >       mutex_lock(&acpi_ioremap_lock);
> > --
> > 2.25.1
> >