Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758546AbaJ3Ick (ORCPT ); Thu, 30 Oct 2014 04:32:40 -0400 Received: from mail-pd0-f171.google.com ([209.85.192.171]:43700 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758123AbaJ3Icg (ORCPT ); Thu, 30 Oct 2014 04:32:36 -0400 Message-ID: <5451F728.6060002@linaro.org> Date: Thu, 30 Oct 2014 16:30:32 +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: "Rafael J. Wysocki" CC: Lorenzo Pieralisi , Catalin Marinas , 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> <20141024173920.GB8303@red-moon> <544E1732.5090902@linaro.org> <4773594.btHp9vXayV@vostro.rjw.lan> In-Reply-To: <4773594.btHp9vXayV@vostro.rjw.lan> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014-10-30 5:33, Rafael J. Wysocki wrote: > On Monday, October 27, 2014 05:58:10 PM Hanjun Guo wrote: >> 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. > > And error prone for that matter. Thanks for the clarify, I will send out a patch set to convert apic_id to phys_id in ACPI processor driver soon, then we don't need to map acpi_id to logical cpu number. 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/