Re: [PATCH v4 02/10] riscv: Define arch_apei_get_mem_attribute for RISC-V

[Sunil V L]

On Wed, May 13, 2026 at 2:13 PM Himanshu Chauhan
<himanshu.chauhan@xxxxxxxxxxxxxxxx> wrote:
>
> ghes_map function uses arch_apei_get_mem_attribute to get the
> protection bits for a given physical address. These protection
> bits are then used to map the physical address.
>
> Signed-off-by: Himanshu Chauhan <himanshu.chauhan@xxxxxxxxxxxxxxxx>
> ---
>  arch/riscv/include/asm/acpi.h | 16 ++++++++++++++++
>  arch/riscv/kernel/acpi.c      | 12 ++++++++++++
>  2 files changed, 28 insertions(+)
>
> diff --git a/arch/riscv/include/asm/acpi.h b/arch/riscv/include/asm/acpi.h
> index 26ab37c171bc..c142db9f81a7 100644
> --- a/arch/riscv/include/asm/acpi.h
> +++ b/arch/riscv/include/asm/acpi.h
> @@ -14,6 +14,7 @@
>
>  /* Basic configuration for ACPI */
>  #ifdef CONFIG_ACPI
> +pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
>
>  typedef u64 phys_cpuid_t;
>  #define PHYS_CPUID_INVALID INVALID_HARTID
> @@ -27,6 +28,21 @@ extern int acpi_disabled;
>  extern int acpi_noirq;
>  extern int acpi_pci_disabled;
>
> +#ifdef CONFIG_ACPI_APEI
> +/*
> + * acpi_disable_cmcff to disable IA-32 Corrected Machine Check (CMC)
> + * Firmware-First mode. It is not required in RISC-V architecture
> + * and is present for compatibility
> + */
> +#define acpi_disable_cmcff 1
> +static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
> +{
> +       return  __acpi_get_mem_attribute(addr);
> +}
> +#else /* CONFIG_ACPI_APEI */
> +#define acpi_disable_cmcff 0
> +#endif /* !CONFIG_ACPI_APEI */
> +
>  static inline void disable_acpi(void)
>  {
>         acpi_disabled = 1;
> diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
> index 068e0b404b6f..7a6770697999 100644
> --- a/arch/riscv/kernel/acpi.c
> +++ b/arch/riscv/kernel/acpi.c
> @@ -204,6 +204,18 @@ struct acpi_madt_rintc *acpi_cpu_get_madt_rintc(int cpu)
>         return &cpu_madt_rintc[cpu];
>  }
>
> +pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
> +{
> +       u64 attr;
> +
> +       attr = efi_mem_attributes(addr);
> +       if (attr & EFI_MEMORY_WB)
> +               return PAGE_KERNEL;
> +       if ((attr & EFI_MEMORY_WC) || (attr & EFI_MEMORY_WT))
> +               return pgprot_writecombine(PAGE_KERNEL);
> +       return PAGE_KERNEL;
> +}
> +
>  /*
>   * __acpi_map_table() will be called before paging_init(), so early_ioremap()
>   * or early_memremap() should be called here to for ACPI table mapping.
>
Reviewed-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>