Re: [PATCH] AMD Thermal Interrupt Support
- From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 25 Dec 2007 14:04:13 -0800
On Mon, 17 Dec 2007 10:54:53 -0800 (PST) rml@xxxxxxxxxx (Russell Leidich) wrote:
Hi,
This patch to 2.6.24-rc5 enables AMD Barcelona CPUs to register thermal throttling events as machine checks, in the
same fashion as the analogous Intel code.
Changed files:
arch/x86/kernel/cpu/mcheck/Makefile
arch/x86/kernel/cpu/mcheck/mce_amd_64.c
arch/x86/kernel/cpu/mcheck/mce_intel_64.c
include/asm-x86/mce.h
New files:
arch/x86/kernel/cpu/mcheck/mce_thermal.c
...
+extern int num_k8_northbridges;
+extern struct pci_dev **k8_northbridges;
Please never add extern declarations in C files - find a suitable header
which is seen by the definition and by all users.
-static int threshold_cpu_callback(struct notifier_block *nfb,
+static int amd_cpu_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
/* cpu was unsigned int to begin with */
unsigned int cpu = (unsigned long)hcpu;
- if (cpu >= NR_CPUS)
- goto out;
-
switch (action) {
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
threshold_create_device(cpu);
- break;
+ if (thermal_apic_init_allowed) {
+ /*
+ * We need to run thermal_apic_init() on the core that
+ * just came online. If we're already on that core,
+ * then directly run it. Otherwise
+ * smp_call_function_single() to that core.
+ */
+ if (cpu == get_cpu())
+ thermal_apic_init(NULL);
+ else
+ smp_call_function_single(cpu,
+ &thermal_apic_init, NULL, 1, 0);
+ put_cpu();
+ }
smp_call_function_single() already takes care of the
called-on-the-right-cpu case.
+ break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
threshold_remove_device(cpu);
@@ -665,12 +692,11 @@ static int threshold_cpu_callback(struct
default:
break;
}
- out:
return NOTIFY_OK;
}
+
+/*
+ * Enable the delivery of thermal interrupts via the local APIC.
+ */
+static void thermal_apic_init(void *unused) {
eek, google coding "style" ;)
Please feed patches through scripts/checkpatch.pl.
+ unsigned int apic_lv_therm;
+
+ /* Set up APIC_LVTTHMR to issue THERMAL_APIC_VECTOR. */
+ apic_lv_therm = apic_read(APIC_LVTTHMR);
+ /*
+ * See if some agent other than this routine has already initialized
+ * APIC_LVTTHMR, i.e. if it's unmasked, but not equal to the value that
+ * we would have programmed, had we been here before on this core.
+ */
+ if ((!(apic_lv_therm & APIC_LVT_MASKED)) && ((apic_lv_therm &
+ (APIC_MODE_MASK | APIC_VECTOR_MASK)) != (APIC_DM_FIXED |
+ THERMAL_APIC_VECTOR))) {
+ unsigned int cpu = smp_processor_id();
afaict this function is called while the calling thread is running
preemptibly. This smp_processor_id() call should have generated a runtime
warning if it was tested with all debug options enabled?
Please see Documentation/SumitChecklist.
+ printk(KERN_CRIT "CPU 0x%x: Thermal monitoring not "
+ "functional.\n", cpu);
+ if ((apic_lv_therm & APIC_MODE_MASK) == APIC_DM_SMI)
+ printk(KERN_DEBUG "Thermal interrupts already "
+ "handled by SMI according to (((local APIC "
+ "base) + 0x330) bit 0x9).\n");
+ else
+ printk(KERN_DEBUG "Thermal interrupts unexpectedly "
+ "enabled at (((local APIC base) + 0x330) bit "
+ "0x10).\n");
+ } else {
+ /*
+ * Configure the Local Thermal Vector Table Entry to issue
+ * issue thermal interrupts to THERMAL_APIC_VECTOR.
+ *
+ * Start by masking off Delivery Mode and Vector.
+ */
+ apic_lv_therm &= ~(APIC_MODE_MASK | APIC_VECTOR_MASK);
+ /* Fixed interrupt, masked for now. */
+ apic_lv_therm |= APIC_LVT_MASKED | APIC_DM_FIXED |
+ THERMAL_APIC_VECTOR;
+ apic_write(APIC_LVTTHMR, apic_lv_therm);
+ /*
+ * The Intel thermal kernel code implies that there may be a
+ * race involving the mask bit, so clear it only now, after
+ * the other bits have settled.
+ */
+ apic_write(APIC_LVTTHMR, apic_lv_therm & ~APIC_LVT_MASKED);
+ }
+}
+
+
+/*
+ * Determine whether or not the northbridges support thermal throttling
+ * interrupts. If so, initialize them for receiving the same, then perform
+ * corresponding APIC initialization on each core.
+ */
+static int smp_thermal_interrupt_init(void)
+{
+ int nb_num;
+ int thermal_registers_functional;
+
+ /*
+ * If there are no recognized northbridges, then we can't talk to the
+ * thermal registers.
+ */
+ thermal_registers_functional = num_k8_northbridges;
+ /*
+ * If any of the northbridges has PCI ID 0x1103, then its thermal
+ * hardware suffers from an erratum which prevents this code from working,
+ * so abort.
+ */
+ for (nb_num = 0; nb_num < num_k8_northbridges; nb_num++) {
+ if ((k8_northbridges[nb_num]->device) == 0x1103) {
+ thermal_registers_functional = 0;
+ break;
+ }
+ }
+ if (thermal_registers_functional) {
+ /*
+ * Assert that we should log thermal throttling events, whenever
+ * we eventually get around to enabling them.
+ */
+ atomic_set(&therm_throt_en, 1);
+ /*
+ * Bind cpu_specific_smp_thermal_interrupt() to
+ * amd_smp_thermal_interrupt().
+ */
+ cpu_specific_smp_thermal_interrupt = amd_smp_thermal_interrupt;
+ smp_thermal_northbridge_init();
+ /*
+ * We've now initialized sufficient fabric to permit the
+ * initialization of the thermal interrupt APIC vectors, such as
+ * when a core comes online and calls amd_cpu_callback().
+ */
+ thermal_apic_init_allowed = 1;
+ /*
+ * Call thermal_apic_init() on each core.
+ */
+ on_each_cpu(&thermal_apic_init, NULL, 1, 0);
+ smp_thermal_early_throttle_check();
+ }
+ return 0;
+}
The logic in this function looks more complex than it needs to be.
if (num_k8_northbridges == 0)
goto out;
for (nb_num = 0; nb_num < num_k8_northbridges; nb_num++) {
if ((k8_northbridges[nb_num]->device) == 0x1103)
goto out;
}
maybe?
--- linux-2.6.24-rc5.orig/arch/x86/kernel/cpu/mcheck/mce_thermal.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.24-rc5/arch/x86/kernel/cpu/mcheck/mce_thermal.c 2007-12-13 12:26:13.057412000 -0800
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2007 Google Inc.
+ *
+ * Written by Mike Waychison <mikew@xxxxxxxxxx> and Russell Leidich <rml@xxxxxxxxxx>.
+ *
+ * CPU-independent thermal interrupt handler.
+ */
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include "mce.h"
+#include <asm/hw_irq.h>
+#include <asm/idle.h>
+
+static void default_smp_thermal_interrupt(void) {}
static void default_smp_thermal_interrupt(void)
{
}
please.
Can this function ever actually be called?
+cpu_specific_smp_thermal_interrupt_callback cpu_specific_smp_thermal_interrupt =
+ default_smp_thermal_interrupt;
+
+/*
+ * Wrapper for the CPU-specific thermal interrupt service routine. Without
+ * this, we'd have to discern the CPU brand at runtime (because support could
+ * be installed for more than one).
+ */
+asmlinkage void smp_thermal_interrupt(void)
+{
+ ack_APIC_irq();
+ exit_idle();
+ irq_enter();
+ cpu_specific_smp_thermal_interrupt();
+ irq_exit();
+}
diff -uprN linux-2.6.24-rc5.orig/include/asm-x86/mce.h linux-2.6.24-rc5/include/asm-x86/mce.h
--- linux-2.6.24-rc5.orig/include/asm-x86/mce.h 2007-12-11 14:31:34.263515000 -0800
+++ linux-2.6.24-rc5/include/asm-x86/mce.h 2007-12-13 14:10:37.923970000 -0800
@@ -113,7 +113,10 @@ static inline void mce_amd_feature_init(
#endif
void mce_log_therm_throt_event(unsigned int cpu, __u64 status);
+typedef void (*cpu_specific_smp_thermal_interrupt_callback)(void);
Yes, this is the case where typedefs are OK. But please put a _t at the end
of the name.
+extern cpu_specific_smp_thermal_interrupt_callback
+ cpu_specific_smp_thermal_interrupt;
extern atomic_t mce_entry;
extern void do_machine_check(struct pt_regs *, long);
--
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