1.1 --- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_dev.c	Mon Jan 09 11:24:02 2006 +0000
     1.2 +++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_dev.c	Mon Jan 09 14:43:46 2006 +0000
     1.3 @@ -109,7 +109,7 @@ static ssize_t xenbus_dev_write(struct f
     1.4  				size_t len, loff_t *ppos)
     1.5  {
     1.6  	struct xenbus_dev_data *u = filp->private_data;
     1.7 -	struct xenbus_dev_transaction *trans;
     1.8 +	struct xenbus_dev_transaction *trans = NULL;
     1.9  	void *reply;
    1.10  
    1.11  	if ((len + u->len) > sizeof(u->u.buffer))
    1.12 @@ -134,14 +134,19 @@ static ssize_t xenbus_dev_write(struct f
    1.13  	case XS_MKDIR:
    1.14  	case XS_RM:
    1.15  	case XS_SET_PERMS:
    1.16 -		reply = xenbus_dev_request_and_reply(&u->u.msg);
    1.17 -		if (IS_ERR(reply))
    1.18 -			return PTR_ERR(reply);
    1.19 -
    1.20  		if (u->u.msg.type == XS_TRANSACTION_START) {
    1.21  			trans = kmalloc(sizeof(*trans), GFP_KERNEL);
    1.22  			if (!trans)
    1.23  				return -ENOMEM;
    1.24 +		}
    1.25 +
    1.26 +		reply = xenbus_dev_request_and_reply(&u->u.msg);
    1.27 +		if (IS_ERR(reply)) {
    1.28 +			kfree(trans);
    1.29 +			return PTR_ERR(reply);
    1.30 +		}
    1.31 +
    1.32 +		if (u->u.msg.type == XS_TRANSACTION_START) {
    1.33  			trans->handle = (struct xenbus_transaction *)
    1.34  				simple_strtoul(reply, NULL, 0);
    1.35  			list_add(&trans->list, &u->transactions);

     2.1 --- a/xen/arch/x86/domain.c	Mon Jan 09 11:24:02 2006 +0000
     2.2 +++ b/xen/arch/x86/domain.c	Mon Jan 09 14:43:46 2006 +0000
     2.3 @@ -689,6 +689,9 @@ static void __context_switch(void)
     2.4      struct vcpu          *p = percpu_ctxt[cpu].curr_vcpu;
     2.5      struct vcpu          *n = current;
     2.6  
     2.7 +    ASSERT(p != n);
     2.8 +    ASSERT(cpus_empty(n->vcpu_dirty_cpumask));
     2.9 +
    2.10      if ( !is_idle_domain(p->domain) )
    2.11      {
    2.12          memcpy(&p->arch.guest_context.user_regs,
    2.13 @@ -748,24 +751,31 @@ static void __context_switch(void)
    2.14  void context_switch(struct vcpu *prev, struct vcpu *next)
    2.15  {
    2.16      unsigned int cpu = smp_processor_id();
    2.17 +    cpumask_t dirty_mask = next->vcpu_dirty_cpumask;
    2.18  
    2.19      ASSERT(local_irq_is_enabled());
    2.20  
    2.21 +    /* Allow at most one CPU at a time to be dirty. */
    2.22 +    ASSERT(cpus_weight(dirty_mask) <= 1);
    2.23 +    if ( unlikely(!cpu_isset(cpu, dirty_mask) && !cpus_empty(dirty_mask)) )
    2.24 +    {
    2.25 +        /* Other cpus call __sync_lazy_execstate from flush ipi handler. */
    2.26 +        flush_tlb_mask(dirty_mask);
    2.27 +    }
    2.28 +
    2.29 +    local_irq_disable();
    2.30 +
    2.31      set_current(next);
    2.32  
    2.33 -    if ( (percpu_ctxt[cpu].curr_vcpu != next) &&
    2.34 -         !is_idle_domain(next->domain) )
    2.35 +    if ( (percpu_ctxt[cpu].curr_vcpu == next) || is_idle_domain(next->domain) )
    2.36      {
    2.37 -        /* This may happen if next has been migrated by the scheduler. */
    2.38 -        if ( unlikely(!cpus_empty(next->vcpu_dirty_cpumask)) )
    2.39 -        {
    2.40 -            ASSERT(!cpu_isset(cpu, next->vcpu_dirty_cpumask));
    2.41 -            sync_vcpu_execstate(next);
    2.42 -            ASSERT(cpus_empty(next->vcpu_dirty_cpumask));
    2.43 -        }
    2.44 +        local_irq_enable();
    2.45 +    }
    2.46 +    else
    2.47 +    {
    2.48 +        __context_switch();
    2.49  
    2.50 -        local_irq_disable();
    2.51 -        __context_switch();
    2.52 +        /* Re-enable interrupts before restoring state which may fault. */
    2.53          local_irq_enable();
    2.54  
    2.55          if ( VMX_DOMAIN(next) )