On Wed, Oct 06, 2010 at 12:41:32PM +0200, Gleb Natapov wrote: > On Tue, Oct 05, 2010 at 04:51:50PM -0300, Marcelo Tosatti wrote: > > On Mon, Oct 04, 2010 at 05:56:32PM +0200, Gleb Natapov wrote: > > > If async page fault is received by idle task or when preemp_count is > > > not zero guest cannot reschedule, so do sti; hlt and wait for page to be > > > ready. vcpu can still process interrupts while it waits for the page to > > > be ready. > > > > > > Acked-by: Rik van Riel <riel@xxxxxxxxxx> > > > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx> > > > --- > > > arch/x86/kernel/kvm.c | 40 ++++++++++++++++++++++++++++++++++------ > > > 1 files changed, 34 insertions(+), 6 deletions(-) > > > > > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > > > index 36fb3e4..f73946f 100644 > > > --- a/arch/x86/kernel/kvm.c > > > +++ b/arch/x86/kernel/kvm.c > > > @@ -37,6 +37,7 @@ > > > #include <asm/cpu.h> > > > #include <asm/traps.h> > > > #include <asm/desc.h> > > > +#include <asm/tlbflush.h> > > > > > > #define MMU_QUEUE_SIZE 1024 > > > > > > @@ -78,6 +79,8 @@ struct kvm_task_sleep_node { > > > wait_queue_head_t wq; > > > u32 token; > > > int cpu; > > > + bool halted; > > > + struct mm_struct *mm; > > > }; > > > > > > static struct kvm_task_sleep_head { > > > @@ -106,6 +109,11 @@ void kvm_async_pf_task_wait(u32 token) > > > struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; > > > struct kvm_task_sleep_node n, *e; > > > DEFINE_WAIT(wait); > > > + int cpu, idle; > > > + > > > + cpu = get_cpu(); > > > + idle = idle_cpu(cpu); > > > + put_cpu(); > > > > > > spin_lock(&b->lock); > > > e = _find_apf_task(b, token); > > > @@ -119,19 +127,33 @@ void kvm_async_pf_task_wait(u32 token) > > > > > > n.token = token; > > > n.cpu = smp_processor_id(); > > > + n.mm = current->active_mm; > > > + n.halted = idle || preempt_count() > 1; > > > + atomic_inc(&n.mm->mm_count); > > > > Can't see why this reference is needed. > I thought that if kernel thread does fault on behalf of some > process mm can go away while kernel thread is sleeping. But it looks > like kernel thread increase reference to mm it runs with by himself, so > may be this is redundant (but not harmful). > Actually it is not redundant. Kernel thread will release reference to active_mm on reschedule. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html