From 23d5ea5d3edcfe899cd91fca87a4af799bcc5794 Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Thu, 6 Sep 2007 16:59:51 +0200 Subject: [PATCH] i386: Fix perfctr watchdog on core duo Fix the NMI watchdog on Intel CoreDuo processor where the kernel would get stuck during boot. The issue is related to errata AE49, where the PERFEVTSEL1 counter does not have a working enable bit. Thus it is not possible to use it for NMI. The patch creates a dedicated wd_ops for CoreDuo which falls back to using PERFEVTSEL0. The other Intel processors supporting the architectural PMU will keep on using PERFEVTSEL1 as this allows other subsystems, such as perfmon, to use PERFEVTSEL0 for PEBS monitoring in particular. Bug initially reported by Daniel Walker. AK: Added comments Signed-off-by: Stephane Eranian Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/i386/kernel/cpu/perfctr-watchdog.c | 28 +++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/arch/i386/kernel/cpu/perfctr-watchdog.c b/arch/i386/kernel/cpu/perfctr-watchdog.c index 4be488e73b..93fecd4b03 100644 --- a/arch/i386/kernel/cpu/perfctr-watchdog.c +++ b/arch/i386/kernel/cpu/perfctr-watchdog.c @@ -263,8 +263,8 @@ static int setup_k7_watchdog(unsigned nmi_hz) unsigned int evntsel; struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk); - perfctr_msr = MSR_K7_PERFCTR0; - evntsel_msr = MSR_K7_EVNTSEL0; + perfctr_msr = wd_ops->perfctr; + evntsel_msr = wd_ops->evntsel; wrmsrl(perfctr_msr, 0UL); @@ -343,8 +343,8 @@ static int setup_p6_watchdog(unsigned nmi_hz) unsigned int evntsel; struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk); - perfctr_msr = MSR_P6_PERFCTR0; - evntsel_msr = MSR_P6_EVNTSEL0; + perfctr_msr = wd_ops->perfctr; + evntsel_msr = wd_ops->evntsel; /* KVM doesn't implement this MSR */ if (wrmsr_safe(perfctr_msr, 0, 0) < 0) @@ -569,8 +569,8 @@ static int setup_intel_arch_watchdog(unsigned nmi_hz) (ebx & ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT)) return 0; - perfctr_msr = MSR_ARCH_PERFMON_PERFCTR1; - evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL1; + perfctr_msr = wd_ops->perfctr; + evntsel_msr = wd_ops->evntsel; wrmsrl(perfctr_msr, 0UL); @@ -605,6 +605,16 @@ static struct wd_ops intel_arch_wd_ops = { .evntsel = MSR_ARCH_PERFMON_EVENTSEL1, }; +static struct wd_ops coreduo_wd_ops = { + .reserve = single_msr_reserve, + .unreserve = single_msr_unreserve, + .setup = setup_intel_arch_watchdog, + .rearm = p6_rearm, + .stop = single_msr_stop_watchdog, + .perfctr = MSR_ARCH_PERFMON_PERFCTR0, + .evntsel = MSR_ARCH_PERFMON_EVENTSEL0, +}; + static void probe_nmi_watchdog(void) { switch (boot_cpu_data.x86_vendor) { @@ -615,6 +625,12 @@ static void probe_nmi_watchdog(void) wd_ops = &k7_wd_ops; break; case X86_VENDOR_INTEL: + /* Work around Core Duo (Yonah) errata AE49 where perfctr1 + doesn't have a working enable bit. */ + if (boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 14) { + wd_ops = &coreduo_wd_ops; + break; + } if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) { wd_ops = &intel_arch_wd_ops; break; -- 2.39.5