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.
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