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

["Zhang, Jonathan Zhixiong" <zjzhang@codeaurora.org>]

Thanks Will. I will create a new patch in this patch set to supplement
arm64's page protection type definitions accordingly to meet the needs
as defined in UEFI 2.5 table 8. More comments inline...

On 7/21/2015 8:08 AM, Will Deacon wrote:
> 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.
Yes, I will define PROT_DEVICE_nGnRnE.
>
>> +
>> +	return PAGE_KERNEL;
>
> About about about WC and WT?
For WC, PROT_NORMAL_NC will be returned.
For WT, I will define PROT_NORNMAL_WT. To enable that, I will also
need to add MT_NORMAL_WT to MAIR_EL1.
>
> Will
>

-- 
Jonathan (Zhixiong) Zhang
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project