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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3] x86/NMI: Allow processing unknown NMIs when watchdog is enabled
On 27/08/14 17:25, Ross Lagerwall wrote:
> Change NMI processing so that if watchdog=force is passed on the
> command-line and the NMI is not caused by a perf counter overflow (i.e.
> likely not a watchdog "tick"), the NMI is handled by the unknown NMI
> handler.
>
> This allows injection of NMIs from IPMI controllers that don't set the
> IOCK/SERR bits to trigger the unknown NMI handler rather than be
> ignored.
>
> Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> CC: Keir Fraser <keir@xxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> ---
>
> Changes since V2:
> Fix processing when watchdog is turned off.
>
> Changes since V1:
> Most of the original behavior is now restored. Now, only if
> watchdog=force is given on the command-line and the NMI is not a
> watchdog tick (i.e. the perf counter has not overflowed) will the
> unknown NMI handler be invoked.
>
> docs/misc/xen-command-line.markdown | 6 ++++--
> xen/arch/x86/nmi.c | 39
> +++++++++++++++++++++++++++++++++++--
> xen/arch/x86/traps.c | 7 ++++---
> xen/include/asm-x86/apic.h | 2 +-
> xen/include/asm-x86/nmi.h | 3 +++
> 5 files changed, 49 insertions(+), 8 deletions(-)
>
> diff --git a/docs/misc/xen-command-line.markdown
> b/docs/misc/xen-command-line.markdown
> index a8cab59..1cbcca4 100644
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -1245,12 +1245,14 @@ As the BTS virtualisation is not 100% safe and
> because of the nehalem quirk
> don't use the vpmu flag on production systems with Intel cpus!
>
> ### watchdog
> -> `= <boolean>`
> +> `= force | <boolean>`
>
> > Default: `false`
>
> Run an NMI watchdog on each processor. If a processor is stuck for
> -longer than the **watchdog\_timeout**, a panic occurs.
> +longer than the **watchdog\_timeout**, a panic occurs. When `force` is
> +specified, in addition to running an NMI watchdog on each processor,
> +unknown NMIs will still be processed.
>
> ### watchdog\_timeout
> > `= <integer>`
> diff --git a/xen/arch/x86/nmi.c b/xen/arch/x86/nmi.c
> index c4427a6..873427f 100644
> --- a/xen/arch/x86/nmi.c
> +++ b/xen/arch/x86/nmi.c
> @@ -43,7 +43,18 @@ static DEFINE_PER_CPU(unsigned int, nmi_timer_ticks);
>
> /* opt_watchdog: If true, run a watchdog NMI on each processor. */
> bool_t __initdata opt_watchdog = 0;
> -boolean_param("watchdog", opt_watchdog);
> +
> +/* watchdog_force: If true, process unknown NMIs when running the watchdog.
> */
> +bool_t watchdog_force = 0;
> +
> +static void __init parse_watchdog(char * s)
> +{
> + opt_watchdog = !!parse_bool(s);
A lot of code in Xen gets the use of parse_bool() wrong. In this case,
opt_watchdog will be set if garbage is passed in the parameter, which is
a change in behaviour from before.
I recommend:
switch ( parse_bool(s) )
{
case 0:
break;
default:
if ( !strcmp(s, "force") )
watchdog_force = 1;
/* fall through */
case 1:
opt_watchdog = 1;
}
~Andrew
> +
> + if ( !strcmp(s, "force") )
> + watchdog_force = 1;
> +}
> +custom_param("watchdog", parse_watchdog);
>
> /* opt_watchdog_timeout: Number of seconds to wait before panic. */
> static unsigned int opt_watchdog_timeout = 5;
> @@ -82,6 +93,7 @@ int nmi_active;
> #define K7_EVNTSEL_USR (1 << 16)
> #define K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING 0x76
> #define K7_NMI_EVENT K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING
> +#define K7_EVENT_WIDTH 32
>
> #define P6_EVNTSEL0_ENABLE (1 << 22)
> #define P6_EVNTSEL_INT (1 << 20)
> @@ -89,10 +101,12 @@ int nmi_active;
> #define P6_EVNTSEL_USR (1 << 16)
> #define P6_EVENT_CPU_CLOCKS_NOT_HALTED 0x79
> #define CORE_EVENT_CPU_CLOCKS_NOT_HALTED 0x3c
> +#define P6_EVENT_WIDTH 32
>
> #define P4_ESCR_EVENT_SELECT(N) ((N)<<25)
> #define P4_CCCR_OVF_PMI0 (1<<26)
> #define P4_CCCR_OVF_PMI1 (1<<27)
> +#define P4_CCCR_OVF (1<<31)
> #define P4_CCCR_THRESHOLD(N) ((N)<<20)
> #define P4_CCCR_COMPLEMENT (1<<19)
> #define P4_CCCR_COMPARE (1<<18)
> @@ -432,8 +446,10 @@ int __init watchdog_setup(void)
> return 0;
> }
>
> -void nmi_watchdog_tick(const struct cpu_user_regs *regs)
> +/* Returns false if this was not a watchdog NMI, true otherwise */
> +bool_t nmi_watchdog_tick(const struct cpu_user_regs *regs)
> {
> + bool_t watchdog_tick = 1;
> unsigned int sum = this_cpu(nmi_timer_ticks);
>
> if ( (this_cpu(last_irq_sums) == sum) && watchdog_enabled() )
> @@ -459,8 +475,15 @@ void nmi_watchdog_tick(const struct cpu_user_regs *regs)
>
> if ( nmi_perfctr_msr )
> {
> + uint64_t msr_content;
> +
> + /* Work out if this is a watchdog tick by checking for overflow. */
> if ( nmi_perfctr_msr == MSR_P4_IQ_PERFCTR0 )
> {
> + rdmsrl(MSR_P4_IQ_CCCR0, msr_content);
> + if ( !(msr_content & P4_CCCR_OVF) )
> + watchdog_tick = 0;
> +
> /*
> * P4 quirks:
> * - An overflown perfctr will assert its interrupt
> @@ -473,14 +496,26 @@ void nmi_watchdog_tick(const struct cpu_user_regs *regs)
> }
> else if ( nmi_perfctr_msr == MSR_P6_PERFCTR0 )
> {
> + rdmsrl(MSR_P6_PERFCTR0, msr_content);
> + if ( msr_content & (1ULL << P6_EVENT_WIDTH) )
> + watchdog_tick = 0;
> +
> /*
> * Only P6 based Pentium M need to re-unmask the apic vector but
> * it doesn't hurt other P6 variants.
> */
> apic_write(APIC_LVTPC, APIC_DM_NMI);
> }
> + else if ( nmi_perfctr_msr == MSR_K7_PERFCTR0 )
> + {
> + rdmsrl(MSR_K7_PERFCTR0, msr_content);
> + if ( msr_content & (1ULL << K7_EVENT_WIDTH) )
> + watchdog_tick = 0;
> + }
> write_watchdog_counter(NULL);
> }
> +
> + return watchdog_tick;
> }
>
> /*
> diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
> index 71be2ae..7f5306f 100644
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -3306,14 +3306,15 @@ void do_nmi(const struct cpu_user_regs *regs)
> {
> unsigned int cpu = smp_processor_id();
> unsigned char reason;
> + bool_t handle_unknown = 0;
>
> ++nmi_count(cpu);
>
> if ( nmi_callback(regs, cpu) )
> return;
>
> - if ( nmi_watchdog )
> - nmi_watchdog_tick(regs);
> + if ( !nmi_watchdog || (!nmi_watchdog_tick(regs) && watchdog_force) )
> + handle_unknown = 1;
>
> /* Only the BSP gets external NMIs from the system. */
> if ( cpu == 0 )
> @@ -3323,7 +3324,7 @@ void do_nmi(const struct cpu_user_regs *regs)
> pci_serr_error(regs);
> if ( reason & 0x40 )
> io_check_error(regs);
> - if ( !(reason & 0xc0) && !nmi_watchdog )
> + if ( !(reason & 0xc0) && handle_unknown )
> unknown_nmi_error(regs, reason);
> }
> }
> diff --git a/xen/include/asm-x86/apic.h b/xen/include/asm-x86/apic.h
> index 5d7623f..6697245 100644
> --- a/xen/include/asm-x86/apic.h
> +++ b/xen/include/asm-x86/apic.h
> @@ -206,7 +206,7 @@ extern void release_lapic_nmi(void);
> extern void self_nmi(void);
> extern void disable_timer_nmi_watchdog(void);
> extern void enable_timer_nmi_watchdog(void);
> -extern void nmi_watchdog_tick (const struct cpu_user_regs *regs);
> +extern bool_t nmi_watchdog_tick (const struct cpu_user_regs *regs);
> extern int APIC_init_uniprocessor (void);
> extern void disable_APIC_timer(void);
> extern void enable_APIC_timer(void);
> diff --git a/xen/include/asm-x86/nmi.h b/xen/include/asm-x86/nmi.h
> index 4504fe1..2c92db9 100644
> --- a/xen/include/asm-x86/nmi.h
> +++ b/xen/include/asm-x86/nmi.h
> @@ -8,6 +8,9 @@ struct cpu_user_regs;
>
> /* Watchdog boolean from the command line */
> extern bool_t opt_watchdog;
> +
> +/* Watchdog force parameter from the command line */
> +extern bool_t watchdog_force;
>
> typedef int (*nmi_callback_t)(const struct cpu_user_regs *regs, int cpu);
>
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