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" <zjzh...@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 <zjzh...@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
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