Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751860AbaJ0KAR (ORCPT ); Mon, 27 Oct 2014 06:00:17 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:40342 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751363AbaJ0KAO (ORCPT ); Mon, 27 Oct 2014 06:00:14 -0400 Message-ID: <544E1732.5090902@linaro.org> Date: Mon, 27 Oct 2014 17:58:10 +0800 From: Hanjun Guo User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Lorenzo Pieralisi CC: Catalin Marinas , "Rafael J. Wysocki" , Mark Rutland , Olof Johansson , "grant.likely@linaro.org" , Will Deacon , "graeme.gregory@linaro.org" , Arnd Bergmann , Sudeep Holla , "jcm@redhat.com" , Jason Cooper , Marc Zyngier , Bjorn Helgaas , Daniel Lezcano , Mark Brown , Rob Herring , Robert Richter , Lv Zheng , Robert Moore , Liviu Dudau , Randy Dunlap , Charles Garcia-Tobin , "Kangkang.Shen@huawei.com" , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linaro-acpi@lists.linaro.org" Subject: Re: [PATCH v5 12/18] ACPI / processor: Make it possible to get CPU hardware ID via GICC References: <1413553034-20956-1-git-send-email-hanjun.guo@linaro.org> <1413553034-20956-13-git-send-email-hanjun.guo@linaro.org> <20141024173920.GB8303@red-moon> In-Reply-To: <20141024173920.GB8303@red-moon> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014-10-25 1:39, Lorenzo Pieralisi wrote: > On Fri, Oct 17, 2014 at 02:37:08PM +0100, Hanjun Guo wrote: >> Introduce a new function map_gicc_mpidr() to allow MPIDRs to be obtained >> from the GICC Structure introduced by ACPI 5.1. >> >> MPIDR is the CPU hardware ID as local APIC ID on x86 platform, so we use >> MPIDR not the GIC CPU interface ID to identify CPUs. >> >> Signed-off-by: Hanjun Guo >> --- >> arch/arm64/include/asm/acpi.h | 29 +++++++++++++++++++++++++++++ >> arch/arm64/kernel/acpi.c | 1 - >> drivers/acpi/processor_core.c | 37 +++++++++++++++++++++++++++++++++++++ >> 3 files changed, 66 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h >> index c82d4a1..483ff45 100644 >> --- a/arch/arm64/include/asm/acpi.h >> +++ b/arch/arm64/include/asm/acpi.h >> @@ -12,6 +12,8 @@ >> #ifndef _ASM_ACPI_H >> #define _ASM_ACPI_H >> >> +#include >> + >> /* Basic configuration for ACPI */ >> #ifdef CONFIG_ACPI >> #define acpi_strict 1 /* No out-of-spec workarounds on ARM64 */ >> @@ -45,6 +47,33 @@ static inline void enable_acpi(void) >> acpi_noirq = 0; >> } >> >> +/* MPIDR value provided in GICC structure is 64 bits, but the >> + * existing apic_id (CPU hardware ID) using in acpi processor >> + * driver is 32-bit, to conform to the same datatype we need >> + * to repack the GICC structure MPIDR. >> + * >> + * Only 32 bits of MPIDR are used: >> + * >> + * Bits [0:7] Aff0; >> + * Bits [8:15] Aff1; >> + * Bits [16:23] Aff2; >> + * Bits [32:39] Aff3; >> + */ >> +static inline u32 pack_mpidr(u64 mpidr) >> +{ >> + return (u32) ((mpidr & 0xff00000000) >> 8) | mpidr; >> +} >> + >> +/* >> + * The ACPI processor driver for ACPI core code needs this macro >> + * to find out this cpu was already mapped (mapping from CPU hardware >> + * ID to CPU logical ID) or not. >> + * >> + * cpu_logical_map(cpu) is the mapping of MPIDR and the logical cpu, >> + * and MPIDR is the cpu hardware ID we needed to pack. >> + */ >> +#define cpu_physical_id(cpu) pack_mpidr(cpu_logical_map(cpu)) >> + >> /* >> * It's used from ACPI core in kdump to boot UP system with SMP kernel, >> * with this check the ACPI core will not override the CPU index >> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c >> index 34837e0..e91ec76 100644 >> --- a/arch/arm64/kernel/acpi.c >> +++ b/arch/arm64/kernel/acpi.c >> @@ -24,7 +24,6 @@ >> #include >> #include >> >> -#include >> #include >> #include >> >> diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c >> index e32321c..4007313 100644 >> --- a/drivers/acpi/processor_core.c >> +++ b/drivers/acpi/processor_core.c >> @@ -64,6 +64,38 @@ static int map_lsapic_id(struct acpi_subtable_header *entry, >> return 0; >> } >> >> +/* >> + * On ARM platform, MPIDR value is the hardware ID as apic ID >> + * on Intel platforms >> + */ >> +static int map_gicc_mpidr(struct acpi_subtable_header *entry, >> + int device_declaration, u32 acpi_id, int *mpidr) >> +{ >> + struct acpi_madt_generic_interrupt *gicc = >> + container_of(entry, struct acpi_madt_generic_interrupt, header); >> + >> + if (!(gicc->flags & ACPI_MADT_ENABLED)) >> + return -ENODEV; >> + >> + /* In the GIC interrupt model, logical processors are >> + * required to have a Processor Device object in the DSDT, >> + * so we should check device_declaration here >> + */ >> + if (device_declaration && (gicc->uid == acpi_id)) { >> + /* >> + * Only bits [0:7] Aff0, bits [8:15] Aff1, bits [16:23] Aff2 >> + * and bits [32:39] Aff3 are meaningful, so pack the Affx >> + * fields into a single 32 bit identifier to accommodate the >> + * acpi processor drivers. >> + */ >> + *mpidr = ((gicc->arm_mpidr & 0xff00000000) >> 8) >> + | gicc->arm_mpidr; > > The simple fact that you define a function to pack the mpidr value and > you can't use it here because this is *generic* code is telling, and > a very bad omen. At the cost of sounding like a broken record, I do not > like this mpidr->apic->logical_cpu song and dance at all. > ACPI is peppered with code (eg hotplug is another example, CPUidle driver > even worse) that is supposed to be generic but contains x86 code to carry > out this cpuid conversion, I really think that in order to start an ARM64 > ACPI port properly we should at least try to factor out this physical to > logical cpu id conversion, and it is not the first time that I mention this > on the lists. I know, thanks for pointing this out. As I replied in previous version of this patch set, apic_id is x86/ia64 specific, but the meaning behind it is not. It means the CPU hardware id to identify itself in the system, it just like MPIDR on ARM. I will send out a patch for RFC to convert apic_id to physid which is generic for all platforms. > > I will also talk to Rafael about this at the earliest opportunity, I > guess that x86 code relies on apic-id because some ACPI versions could > not rely on the acpi-id or some other reasons I have to investigate. As ACPI spec (section 8.4, Declaring Processors) said, Each processor in the system must be declared in the ACPI namespace, so each cpu will have acpi_id in all ACPI versions, and in theory we can map acpi_id to logical cpu id if we want to. But things are complicated, apic_id is connected to many tables, MADT for smp init, DSDT for device driver, and SRAT for NUMA (there is no acpi_id in it, ONLY has apic_id in the table for x86/ia64), so if we want to factor the code to map acpi_id to logical cpu id, we need to modify: - ACPI drivers; - SMP init for x86 and ia64 - the mappings for NUMA init for x86 and ia64 that will be lots of work I think. I'm willing to discuss this further and come out a solution, please comment on what I said and share your ideas :) Thanks Hanjun -- 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/