Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757377AbaJ2VMe (ORCPT ); Wed, 29 Oct 2014 17:12:34 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:61090 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756966AbaJ2VMc (ORCPT ); Wed, 29 Oct 2014 17:12:32 -0400 From: "Rafael J. Wysocki" To: Hanjun Guo 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 Date: Wed, 29 Oct 2014 22:33:06 +0100 Message-ID: <4773594.btHp9vXayV@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.16.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <544E1732.5090902@linaro.org> References: <1413553034-20956-1-git-send-email-hanjun.guo@linaro.org> <20141024173920.GB8303@red-moon> <544E1732.5090902@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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/