Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933484AbbHLFii (ORCPT ); Wed, 12 Aug 2015 01:38:38 -0400 Received: from mail-ig0-f180.google.com ([209.85.213.180]:34197 "EHLO mail-ig0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932127AbbHLFih (ORCPT ); Wed, 12 Aug 2015 01:38:37 -0400 MIME-Version: 1.0 In-Reply-To: <20150811215748.GA8173@codeblueprint.co.uk> References: <1439054333-21766-1-git-send-email-zjzhang@codeaurora.org> <1439054333-21766-5-git-send-email-zjzhang@codeaurora.org> <20150811215748.GA8173@codeblueprint.co.uk> Date: Wed, 12 Aug 2015 07:38:36 +0200 Message-ID: Subject: Re: [PATCH V11 4/5] arm64: apei: implement arch_apei_get_mem_attributes() From: Ard Biesheuvel To: Matt Fleming Cc: "Jonathan (Zhixiong) Zhang" , Catalin Marinas , Will Deacon , Fu Wei , Al Stone , Borislav Petkov , Matt Fleming , "Rafael J. Wysocki" , Hanjun Guo , Leif Lindholm , "linux-kernel@vger.kernel.org" , Linaro ACPI Mailman List , Timur Tabi Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3162 Lines: 86 On 11 August 2015 at 23:57, Matt Fleming wrote: > On Sat, 08 Aug, at 10:18:52AM, Jonathan (Zhixiong) Zhang wrote: >> From: "Jonathan (Zhixiong) Zhang" >> >> Table 8 of UEFI 2.5 section 2.3.6.1 defines mappings from EFI >> memory types to MAIR attribute encodings for arm64. >> >> If the physical address has memory attributes defined by EFI >> memmap as EFI_MEMORY_[UC|WC|WT], return approprate page protection >> type according to the UEFI spec. Otherwise, return PAGE_KERNEL. >> >> Reviewed-by: Catalin Marinas >> Acked-by: Hanjun Guo >> Signed-off-by: Jonathan (Zhixiong) Zhang >> --- >> arch/arm64/include/asm/acpi.h | 30 ++++++++++++++++++++++++++++++ >> 1 file changed, 30 insertions(+) >> >> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h >> index 614096732839..b77a2d133da9 100644 >> --- a/arch/arm64/include/asm/acpi.h >> +++ b/arch/arm64/include/asm/acpi.h >> @@ -19,6 +19,11 @@ >> #include >> #include >> >> +#ifdef CONFIG_ACPI_APEI >> +#include >> +#include >> +#endif >> + >> /* Macros for consistency checks of the GICC subtable of MADT */ >> #define ACPI_MADT_GICC_LENGTH \ >> (acpi_gbl_FADT.header.revision < 6 ? 76 : 80) >> @@ -91,4 +95,29 @@ 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) >> +{ >> + /* >> + * According to "Table 8 Map: EFI memory types to AArch64 memory types" >> + * of UEFI 2.5 section 2.3.6.1, each EFI memory type is mapped to >> + * corresponding MAIR attribute encoding. >> + * The EFI memory attribute advises all possible capabilities of a >> + * memory region. We use the most efficient capability. >> + */ >> + >> + u64 attr; >> + >> + attr = efi_mem_attributes(addr); >> + if (attr & EFI_MEMORY_WB) >> + return PAGE_KERNEL; >> + if (attr & EFI_MEMORY_WT) >> + return __pgprot(PROT_NORMAL_WT); >> + if (attr & EFI_MEMORY_WC) >> + return __pgprot(PROT_NORMAL_NC); >> + return __pgprot(PROT_DEVICE_nGnRnE); >> +} >> +#endif >> + >> #endif /*_ASM_ACPI_H*/ > > Everyone happy with this change? Ard? > Yes, this looks fine. As long as any region that has the EFI_MEMORY_WB attribute gets mapped as PAGE_KERNEL, we know we won't be violating any architectural mismatched attributes constraints (since all EFI_MEMORY_WB regions, even the occupied ones, are covered by the kernel direct mapping as well) For the other ones, it is merely an optimization, but arguably still an improvement. Reviewed-by: Ard Biesheuvel Thanks, Ard. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/