Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752874AbaAVPxm (ORCPT ); Wed, 22 Jan 2014 10:53:42 -0500 Received: from service87.mimecast.com ([91.220.42.44]:50263 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752070AbaAVPxi convert rfc822-to-8bit (ORCPT ); Wed, 22 Jan 2014 10:53:38 -0500 Date: Wed, 22 Jan 2014 15:53:31 +0000 From: Lorenzo Pieralisi To: Hanjun Guo Cc: "Rafael J. Wysocki" , Catalin Marinas , Will Deacon , Russell King - ARM Linux , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "grant.likely@linaro.org" , Matthew Garrett , Olof Johansson , Linus Walleij , Bjorn Helgaas , Rob Herring , Mark Rutland , Arnd Bergmann , "patches@linaro.org" , "linux-kernel@vger.kernel.org" , "linaro-kernel@lists.linaro.org" , "linaro-acpi@lists.linaro.org" , Charles Garcia-Tobin Subject: Re: [PATCH 10/20] ARM64 / ACPI: Enumerate possible/present CPU set and map logical cpu id to APIC id Message-ID: <20140122155331.GD24288@e102568-lin.cambridge.arm.com> References: <1389961514-13562-1-git-send-email-hanjun.guo@linaro.org> <1389961514-13562-11-git-send-email-hanjun.guo@linaro.org> MIME-Version: 1.0 In-Reply-To: <1389961514-13562-11-git-send-email-hanjun.guo@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginalArrivalTime: 22 Jan 2014 15:53:32.0919 (UTC) FILETIME=[1A2E2070:01CF178A] X-MC-Unique: 114012215533506301 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 17, 2014 at 12:25:04PM +0000, Hanjun Guo wrote: [...] > +/* map logic cpu id to physical GIC id */ > +extern int arm_cpu_to_apicid[NR_CPUS]; > +#define cpu_physical_id(cpu) arm_cpu_to_apicid[cpu] Sudeep already commented on this, please update it accordingly. > + > #else /* !CONFIG_ACPI */ > #define acpi_disabled 1 /* ACPI sometimes enabled on ARM */ > #define acpi_noirq 1 /* ACPI sometimes enabled on ARM */ > diff --git a/drivers/acpi/plat/arm-core.c b/drivers/acpi/plat/arm-core.c > index 8ba3e6f..1d9b789 100644 > --- a/drivers/acpi/plat/arm-core.c > +++ b/drivers/acpi/plat/arm-core.c > @@ -31,6 +31,7 @@ > #include > > #include > +#include > > /* > * We never plan to use RSDT on arm/arm64 as its deprecated in spec but this > @@ -52,6 +53,13 @@ EXPORT_SYMBOL(acpi_pci_disabled); > */ > static u64 acpi_lapic_addr __initdata; Is this variable actually needed ? > > +/* available_cpus here means enabled cpu in MADT */ > +static int available_cpus; Ditto. > + > +/* Map logic cpu id to physical GIC id (physical CPU id). */ > +int arm_cpu_to_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 }; > +static int boot_cpu_apic_id = -1; Do we need all these variables ? I think we should reuse cpu_logical_map data structures for that, it looks suspiciously familiar. > #define BAD_MADT_ENTRY(entry, end) ( \ > (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ > ((struct acpi_subtable_header *)entry)->length < sizeof(*entry)) > @@ -132,6 +140,55 @@ static int __init acpi_parse_madt(struct acpi_table_header *table) > * Please refer to chapter5.2.12.14/15 of ACPI 5.0 > */ > > +/** > + * acpi_register_gic_cpu_interface - register a gic cpu interface and > + * generates a logic cpu number > + * @id: gic cpu interface id to register > + * @enabled: this cpu is enabled or not > + * > + * Returns the logic cpu number which maps to the gic cpu interface > + */ > +static int acpi_register_gic_cpu_interface(int id, u8 enabled) > +{ > + int cpu; > + > + if (id >= MAX_GIC_CPU_INTERFACE) { > + pr_info(PREFIX "skipped apicid that is too big\n"); > + return -EINVAL; > + } > + > + total_cpus++; > + if (!enabled) > + return -EINVAL; > + > + if (available_cpus >= NR_CPUS) { > + pr_warn(PREFIX "NR_CPUS limit of %d reached," > + " Processor %d/0x%x ignored.\n", NR_CPUS, total_cpus, id); > + return -EINVAL; > + } Hmm...what if you are missing the boot CPU ? It is a worthy check. Have a look at smp_init_cpus(), it does not bail out on cpu>= NR_CPUS because you do want to make sure that the DT contains the boot CPU node. Same logic applies. > + > + available_cpus++; > + Is available_cpus != num_possible_cpus() ? It does not look like hence available_cpus can go. > + /* allocate a logic cpu id for the new comer */ > + if (boot_cpu_apic_id == id) { > + /* > + * boot_cpu_init() already hold bit 0 in cpu_present_mask > + * for BSP, no need to allocte again. > + */ > + cpu = 0; > + } else { > + cpu = cpumask_next_zero(-1, cpu_present_mask); > + } > + > + /* map the logic cpu id to APIC id */ > + arm_cpu_to_apicid[cpu] = id; > + > + set_cpu_present(cpu, true); > + set_cpu_possible(cpu, true); This is getting nasty. Before adding this patch and previous ones we need to put in place a method for the kernel to make a definite choice between ACPI and DT and stick to that. We can't initialize the logical map twice (which will happen if your DT has valid cpu nodes and a chosen node pointing to proper ACPI tables) or even having some entries initialized from DT and others by ACPI. It is a big fat no-no, please update the series accordingly. > + > + return cpu; > +} > + > static int __init > acpi_parse_gic(struct acpi_subtable_header *header, const unsigned long end) > { > @@ -144,6 +201,16 @@ acpi_parse_gic(struct acpi_subtable_header *header, const unsigned long end) > > acpi_table_print_madt_entry(header); > > + /* > + * We need to register disabled CPU as well to permit > + * counting disabled CPUs. This allows us to size > + * cpus_possible_map more accurately, to permit > + * to not preallocating memory for all NR_CPUS > + * when we use CPU hotplug. > + */ > + acpi_register_gic_cpu_interface(processor->gic_id, > + processor->flags & ACPI_MADT_ENABLED); > + > return 0; > } > > @@ -186,6 +253,19 @@ static int __init acpi_parse_madt_gic_entries(void) > return count; > } > > +#ifdef CONFIG_SMP > + if (available_cpus == 0) { > + pr_info(PREFIX "Found 0 CPUs; assuming 1\n"); > + arm_cpu_to_apicid[available_cpus] = > + read_cpuid_mpidr() & MPIDR_HWID_BITMASK; > + available_cpus = 1; /* We've got at least one of these */ > + } I'd rather check the MADT for at least the boot cpu to present, if it is not ACPI tables are horribly buggy and the kernel should barf on that. > +#endif > + > + /* Make boot-up look pretty */ > + pr_info("%d CPUs available, %d CPUs total\n", available_cpus, > + total_cpus); Ok, now, how can we use the "disabled" CPUs == (total_cpus - available_cpus) ? Are we keeping track of them in the kernel at all ? It does not look like, so I wonder whether we need this bit of info. I do not see why it is pretty to know that there are disabled, aka unusable CPUs. > return 0; > } > > @@ -321,6 +401,9 @@ int __init early_acpi_boot_init(void) > if (acpi_disabled) > return -ENODEV; > > + /* Get the boot CPU's GIC cpu interface id before MADT parsing */ > + boot_cpu_apic_id = read_cpuid_mpidr() & MPIDR_HWID_BITMASK; See Sudeep's comment. Thanks, Lorenzo -- 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/