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SubjectRe: [PATCH] 2.4.1-ac1 UP-APIC/NMI watchdog fixes
On Fri, 2 Feb 2001, Mikael Pettersson wrote:

> > I'm unsure about the K7_NMI_EVENT macro -- I think it should go into
> > include/asm-i386/msr.h, but the comment should remain here. It should get
> > reworded a bit in this case, I suppose, though.
>
> I'd prefer to keep it in nmi.c -- it doesn't really have any relevance
> elsewhere. I made a macro of it so that I wouldn't need any #ifdef:s
> or long explanations in the code proper.

I'm worrying of numeric constants scattered throughout the source. As
0x76 is a generic K7 performance monitoring event it should exist in
include/asm-i386/msr.h only and be assigned to a macro with a readable
name. That's not a problem now, when it's only used in a single place,
but it will become a problem once somebody uses the constant elsewhere --
I bet he won't bother to search through the whole Linux tree to check if
it's already assigned a macro.

The name is certainly inappropriate for include/asm-i386/msr.h. Another
one should be used there and K7_NMI_EVENT defined to substitute it.

> ... however, nmi_perfctr_msr could serve this purpose since it will be
> non-zero if and only if (cpu_has_apic && nmi_watchdog == NMI_LOCAL_APIC).
> So I would actually suggest something like:
>
> if (nmi_perfctr_msr)
> wrmsr(nmi_perfctr_msr, -(cpu_khz/HZ*1000), -1);

Of course. Here is an updated patch.

Maciej

--
+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+--------------------------------------------------------------+
+ e-mail: macro@ds2.pg.gda.pl, PGP key available +

patch-2.4.1-ac1-upapic-21
diff -up --recursive --new-file linux-2.4.1-ac1.macro/arch/i386/kernel/apic.c linux-2.4.1-ac1/arch/i386/kernel/apic.c
--- linux-2.4.1-ac1.macro/arch/i386/kernel/apic.c Fri Feb 2 12:32:24 2001
+++ linux-2.4.1-ac1/arch/i386/kernel/apic.c Fri Feb 2 13:25:21 2001
@@ -885,10 +885,10 @@ asmlinkage void smp_error_interrupt(void
* This initializes the IO-APIC and APIC hardware if this is
* a UP kernel.
*/
-void __init APIC_init_uniprocessor (void)
+int __init APIC_init_uniprocessor (void)
{
if (!smp_found_config && !cpu_has_apic)
- return;
+ return -1;

/*
* Complain if the BIOS pretends there is one.
@@ -896,7 +896,7 @@ void __init APIC_init_uniprocessor (void
if (!cpu_has_apic && APIC_INTEGRATED(apic_version[boot_cpu_id])) {
printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
boot_cpu_id);
- return;
+ return -1;
}

verify_local_APIC();
@@ -915,4 +915,6 @@ void __init APIC_init_uniprocessor (void
setup_IO_APIC();
#endif
setup_APIC_clocks();
+
+ return 0;
}
diff -up --recursive --new-file linux-2.4.1-ac1.macro/arch/i386/kernel/io_apic.c linux-2.4.1-ac1/arch/i386/kernel/io_apic.c
--- linux-2.4.1-ac1.macro/arch/i386/kernel/io_apic.c Fri Feb 2 12:32:24 2001
+++ linux-2.4.1-ac1/arch/i386/kernel/io_apic.c Fri Feb 2 13:05:37 2001
@@ -38,7 +38,6 @@ static spinlock_t ioapic_lock = SPIN_LOC
/*
* # of IRQ routing registers
*/
-int nr_ioapics;
int nr_ioapic_registers[MAX_IO_APICS];

#if CONFIG_SMP
diff -up --recursive --new-file linux-2.4.1-ac1.macro/arch/i386/kernel/mpparse.c linux-2.4.1-ac1/arch/i386/kernel/mpparse.c
--- linux-2.4.1-ac1.macro/arch/i386/kernel/mpparse.c Fri Feb 2 12:32:24 2001
+++ linux-2.4.1-ac1/arch/i386/kernel/mpparse.c Fri Feb 2 13:05:37 2001
@@ -48,6 +48,8 @@ struct mpc_config_intsrc mp_irqs[MAX_IRQ
/* MP IRQ source entries */
int mp_irq_entries;

+int nr_ioapics;
+
int pic_mode;
unsigned long mp_lapic_addr;

diff -up --recursive --new-file linux-2.4.1-ac1.macro/arch/i386/kernel/nmi.c linux-2.4.1-ac1/arch/i386/kernel/nmi.c
--- linux-2.4.1-ac1.macro/arch/i386/kernel/nmi.c Wed Jan 31 22:01:50 2001
+++ linux-2.4.1-ac1/arch/i386/kernel/nmi.c Fri Feb 2 13:25:21 2001
@@ -82,25 +82,34 @@ __setup("nmi_watchdog=", setup_nmi_watch
/*
* Activate the NMI watchdog via the local APIC.
* Original code written by Keith Owens.
+ * AMD K7 code by Mikael Pettersson.
*/

-#define MSR_K7_EVNTSEL0 0xC0010000
-#define MSR_K7_PERFCTR0 0xC0010004
+static unsigned int nmi_perfctr_msr; /* the MSR to reset in NMI handler */

-void setup_apic_nmi_watchdog (void)
+/* Event 0x76 isn't listed in recent revisions of AMD #22007, and it
+ slows down (but doesn't halt) when the CPU is idle. Unfortunately
+ the K7 doesn't appear to have any other clock-like perfctr event. */
+#define K7_NMI_EVENT 0x76 /* CYCLES_PROCESSOR_IS_RUNNING */
+#define K7_NMI_EVNTSEL ((1<<20)|(3<<16)|K7_NMI_EVENT) /* INT,OS,USR,<event> */
+
+void __init setup_apic_nmi_watchdog (void)
{
int value;

if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
boot_cpu_data.x86 == 6) {
- unsigned evntsel = (1<<20)|(3<<16); /* INT, OS, USR */
-#if 1 /* listed in old docs */
- evntsel |= 0x76; /* CYCLES_PROCESSOR_IS_RUNNING */
-#else /* try this if the above doesn't work */
- evntsel |= 0xC0; /* RETIRED_INSTRUCTIONS */
-#endif
- wrmsr(MSR_K7_EVNTSEL0, 0, 0);
- wrmsr(MSR_K7_PERFCTR0, 0, 0);
+ int i;
+ unsigned int evntsel;
+
+ nmi_perfctr_msr = MSR_K7_PERFCTR0;
+
+ for (i = 0; i < 4; ++i) {
+ wrmsr(MSR_K7_EVNTSEL0 + i, 0, 0);
+ wrmsr(MSR_K7_PERFCTR0 + i, 0, 0);
+ }
+
+ evntsel = K7_NMI_EVNTSEL;
wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
printk("setting K7_PERFCTR0 to %08lx\n", -(cpu_khz/HZ*1000));
wrmsr(MSR_K7_PERFCTR0, -(cpu_khz/HZ*1000), -1);
@@ -112,28 +121,35 @@ void setup_apic_nmi_watchdog (void)
return;
}

- /* clear performance counters 0, 1 */
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+ boot_cpu_data.x86 == 6) {
+
+ nmi_perfctr_msr = MSR_IA32_PERFCTR1;

- wrmsr(MSR_IA32_EVNTSEL0, 0, 0);
- wrmsr(MSR_IA32_EVNTSEL1, 0, 0);
- wrmsr(MSR_IA32_PERFCTR0, 0, 0);
- wrmsr(MSR_IA32_PERFCTR1, 0, 0);
-
- /* send local-APIC timer counter overflow event as an NMI */
-
- value = 1 << 20 /* Interrupt on overflow */
- | 1 << 17 /* OS mode */
- | 1 << 16 /* User mode */
- | 0x79; /* Event, cpu clocks not halted */
- wrmsr(MSR_IA32_EVNTSEL1, value, 0);
- printk("PERFCTR1: %08lx\n", -(cpu_khz/HZ*1000));
- wrmsr(MSR_IA32_PERFCTR1, -(cpu_khz/HZ*1000), 0);
-
- /* Enable performance counters, only using ctr1 */
-
- apic_write_around(APIC_LVTPC, APIC_DM_NMI);
- value = 1 << 22;
- wrmsr(MSR_IA32_EVNTSEL0, value, 0);
+ /* clear performance counters 0, 1 */
+
+ wrmsr(MSR_IA32_EVNTSEL0, 0, 0);
+ wrmsr(MSR_IA32_EVNTSEL1, 0, 0);
+ wrmsr(MSR_IA32_PERFCTR0, 0, 0);
+ wrmsr(MSR_IA32_PERFCTR1, 0, 0);
+
+ /* send local-APIC timer counter overflow event as an NMI */
+
+ value = 1 << 20 /* Interrupt on overflow */
+ | 1 << 17 /* OS mode */
+ | 1 << 16 /* User mode */
+ | 0x79; /* Event, cpu clocks not halted */
+ wrmsr(MSR_IA32_EVNTSEL1, value, 0);
+ printk("PERFCTR1: %08lx\n", -(cpu_khz/HZ*1000));
+ wrmsr(MSR_IA32_PERFCTR1, -(cpu_khz/HZ*1000), 0);
+
+ /* Enable performance counters, only using ctr1 */
+
+ apic_write_around(APIC_LVTPC, APIC_DM_NMI);
+ value = 1 << 22;
+ wrmsr(MSR_IA32_EVNTSEL0, value, 0);
+ return;
+ }
}

static spinlock_t nmi_print_lock = SPIN_LOCK_UNLOCKED;
@@ -190,14 +206,6 @@ void nmi_watchdog_tick (struct pt_regs *
last_irq_sums[cpu] = sum;
alert_counter[cpu] = 0;
}
- if (cpu_has_apic && (nmi_watchdog == NMI_LOCAL_APIC)) {
- /* XXX: nmi_watchdog should carry this info */
- unsigned msr;
- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
- wrmsr(MSR_K7_PERFCTR0, -(cpu_khz/HZ*1000), -1);
- } else {
- wrmsr(MSR_IA32_PERFCTR1, -(cpu_khz/HZ*1000), 0);
- }
- }
+ if (nmi_perfctr_msr)
+ wrmsr(nmi_perfctr_msr, -(cpu_khz/HZ*1000), -1);
}
-
diff -up --recursive --new-file linux-2.4.1-ac1.macro/arch/i386/kernel/smpboot.c linux-2.4.1-ac1/arch/i386/kernel/smpboot.c
--- linux-2.4.1-ac1.macro/arch/i386/kernel/smpboot.c Fri Feb 2 12:32:24 2001
+++ linux-2.4.1-ac1/arch/i386/kernel/smpboot.c Fri Feb 2 13:25:21 2001
@@ -868,12 +868,15 @@ void __init smp_boot_cpus(void)
* get out of here now!
*/
if (!smp_found_config) {
- printk(KERN_NOTICE "SMP motherboard not detected. Using dummy APIC emulation.\n");
+ printk(KERN_NOTICE "SMP motherboard not detected.\n");
#ifndef CONFIG_VISWS
io_apic_irqs = 0;
#endif
cpu_online_map = phys_cpu_present_map = 1;
smp_num_cpus = 1;
+ if (APIC_init_uniprocessor())
+ printk(KERN_NOTICE "Local APIC not detected."
+ " Using dummy APIC emulation.\n");
goto smp_done;
}

@@ -1019,4 +1022,3 @@ void __init smp_boot_cpus(void)
smp_done:
zap_low_mappings();
}
-
diff -up --recursive --new-file linux-2.4.1-ac1.macro/include/asm-i386/apic.h linux-2.4.1-ac1/include/asm-i386/apic.h
--- linux-2.4.1-ac1.macro/include/asm-i386/apic.h Fri Feb 2 12:56:56 2001
+++ linux-2.4.1-ac1/include/asm-i386/apic.h Fri Feb 2 13:25:21 2001
@@ -77,7 +77,7 @@ extern void smp_local_timer_interrupt (s
extern void setup_APIC_clocks (void);
extern void setup_apic_nmi_watchdog (void);
extern inline void nmi_watchdog_tick (struct pt_regs * regs);
-extern void APIC_init_uniprocessor (void);
+extern int APIC_init_uniprocessor (void);

extern unsigned int apic_timer_irqs [NR_CPUS];
extern int check_nmi_watchdog (void);
diff -up --recursive --new-file linux-2.4.1-ac1.macro/include/asm-i386/msr.h linux-2.4.1-ac1/include/asm-i386/msr.h
--- linux-2.4.1-ac1.macro/include/asm-i386/msr.h Fri Feb 2 12:33:07 2001
+++ linux-2.4.1-ac1/include/asm-i386/msr.h Fri Feb 2 13:25:21 2001
@@ -67,4 +67,8 @@
#define MSR_IA32_MC0_MISC_OFFSET 0x3
#define MSR_IA32_MC0_BANK_COUNT 0x4

+
+#define MSR_K7_EVNTSEL0 0xC0010000
+#define MSR_K7_PERFCTR0 0xC0010004
+
#endif
-
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