Re: [PATCH V6 3/4] arm64: apei: implement arch_apei_get_mem_attributes()

[Will Deacon <will.deacon@arm.com>]

On Tue, Jul 21, 2015 at 01:32:38AM +0100, Jonathan (Zhixiong) Zhang wrote:
> From: "Jonathan (Zhixiong) Zhang" <zjzhang@codeaurora.org>
> 
> If the physical address has memory attributes defined by EFI
> memmap as EFI_MEMORY_UC, the page protection type is
> PROT_DEVICE_nGnRE. Otherwise, the page protection type is
> PAGE_KERNEL.
> 
> Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
> ---
> This patch applies cleanly to efi-next-14364 of efi/next and
> arm64-upstream-13521 of arm64/master, but needed slight change
> to apply to next-20150720 of linux-next/master and
> pm+acpi-4.2-rc3 of linux-pm/master. The later two branches
> has newer arch/arm64/include/asm/acpi.h with following patch:
>   b6cfb277378e ACPI / ARM64: add BAD_MADT_GICC_ENTRY() macro
> ---
>  arch/arm64/include/asm/acpi.h | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 39248d3adf5d..42e4fd8aaf34 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -19,6 +19,11 @@
>  #include <asm/psci.h>
>  #include <asm/smp_plat.h>
>  
> +#ifdef CONFIG_ACPI_APEI
> +#include <linux/efi.h>
> +#include <asm/pgtable.h>
> +#endif
> +
>  /* Basic configuration for ACPI */
>  #ifdef	CONFIG_ACPI
>  /* ACPI table mapping after acpi_gbl_permanent_mmap is set */
> @@ -84,4 +89,15 @@ static inline const char *acpi_get_enable_method(int cpu)
>  {
>  	return acpi_psci_present() ? "psci" : NULL;
>  }
> +
> +#ifdef CONFIG_ACPI_APEI
> +static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
> +{
> +	if (efi_mem_attributes(addr) & EFI_MEMORY_UC)
> +		return PROT_DEVICE_nGnRE;

The EFI spec says this should be nGnRnE afaict.

> +
> +	return PAGE_KERNEL;

About about about WC and WT?

Will