Hi Lorenzo,
On 2014年01月22日 23:53, Lorenzo Pieralisi wrote:
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.
Actually after some careful review of the ACPI code, I can't
update it as MPIDR here.
MPIDR can be the ACPI uid and NOT the GIC id, the mapping
of them are something like this in ACPI driver now:
logic cpu id <---> APIC Id (GIC ID) <---> ACPI uid (MPIDR on ARM)
but not logic cpu id <---> ACPI uid directly, you can refer to
the code of processor_core.c
So here I can only map GIC id to logical cpu id.
+
#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 <linux/smp.h>
#include <asm/pgtable.h>
+#include <asm/cputype.h>
/*
* 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 ?
Yes, needed for GIC initialization.
+/* 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.
MPIDR is the different part. if we use MPIDR as GIC id, i think
we can reuse cpu_logical_map, but Sudeep suggested not
use MPIDR as GIC id.
#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.
Thanks, I will review he code you mentioned and find a solution
for ACPI part.
+
+ available_cpus++;
+
Is available_cpus != num_possible_cpus() ? It does not look like hence
available_cpus can go.
No, possible cpus include available cpus and disabled cpus
this is useful for ACPI based CPU hot-plug features.
+ /* 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.
really good catch here :)
so the problem here is that should we use both ACPI and DT in one system?
+
+ 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) ?
For cpus can be hot-added later when system is running.
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.
I will rework this part to get the GIC cpu interface id, not the MPIDR here.
Thanks
Hanjun
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