diff options
Diffstat (limited to 'xen/arch/i386/smp.c')
| -rw-r--r-- | xen/arch/i386/smp.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/xen/arch/i386/smp.c b/xen/arch/i386/smp.c index 0fe283ce09..5ed43d5551 100644 --- a/xen/arch/i386/smp.c +++ b/xen/arch/i386/smp.c @@ -284,10 +284,15 @@ void new_tlbflush_clock_period(void) if ( unlikely(!spin_trylock(&synchronous_ipi_lock)) ) return; - flush_cpumask = tlbflush_mask & ~(1 << smp_processor_id()); - if ( unlikely(flush_cpumask != 0) ) + /* Someone may acquire the lock and execute the flush before us. */ + if ( ((tlbflush_clock+1) & TLBCLOCK_EPOCH_MASK) != 0 ) + goto out; + + if ( smp_num_cpus > 1 ) { - send_IPI_mask(flush_cpumask, INVALIDATE_TLB_VECTOR); + /* Flush everyone else. We definitely flushed just before entry. */ + flush_cpumask = ((1 << smp_num_cpus) - 1) & ~(1 << smp_processor_id()); + send_IPI_allbutself(INVALIDATE_TLB_VECTOR); while ( flush_cpumask != 0 ) { rep_nop(); @@ -295,11 +300,10 @@ void new_tlbflush_clock_period(void) } } - /* No need for cmpxchg updates here: we are protected by tlbstate lock. */ - tlbflush_mask = (1 << smp_num_cpus) - 1; - wmb(); /* Reset the mask before allowing the clock to continue ticking. */ + /* No need for atomicity: we are the only possible updater. */ tlbflush_clock++; + out: spin_unlock(&synchronous_ipi_lock); } |