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xen: add batch completion callbacks

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This adds a mechanism to register a callback function to be called once
a batch of hypercalls has been issued.  This is typically used to unlock
things which must remain locked until the hypercall has taken place.

[ Stable folks: pre-req for 2.6.23 bugfix "xen: deal with stale cr3
  values when unpinning pagetables" ]

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Stable Kernel <stable@kernel.org>
This commit is contained in:
Jeremy Fitzhardinge 2007-10-16 11:51:30 -07:00 committed by Jeremy Fitzhardinge
parent f0d7339427
commit 91e0c5f3da
2 changed files with 29 additions and 3 deletions
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29
arch/x86/xen/multicalls.c
View file

@ -32,7 +32,11 @@
struct mc_buffer {
struct multicall_entry entries[MC_BATCH];
u64 args[MC_ARGS];
unsigned mcidx, argidx;
struct callback {
void (*fn)(void *);
void *data;
} callbacks[MC_BATCH];
unsigned mcidx, argidx, cbidx;
};
static DEFINE_PER_CPU(struct mc_buffer, mc_buffer);
@ -43,6 +47,7 @@ void xen_mc_flush(void)
struct mc_buffer *b = &__get_cpu_var(mc_buffer);
int ret = 0;
unsigned long flags;
int i;
BUG_ON(preemptible());
@ -51,8 +56,6 @@ void xen_mc_flush(void)
local_irq_save(flags);
if (b->mcidx) {
int i;
if (HYPERVISOR_multicall(b->entries, b->mcidx) != 0)
BUG();
for (i = 0; i < b->mcidx; i++)
@ -65,6 +68,13 @@ void xen_mc_flush(void)
local_irq_restore(flags);
for(i = 0; i < b->cbidx; i++) {
struct callback *cb = &b->callbacks[i];
(*cb->fn)(cb->data);
}
b->cbidx = 0;
BUG_ON(ret);
}
@ -88,3 +98,16 @@ struct multicall_space __xen_mc_entry(size_t args)
return ret;
}
void xen_mc_callback(void (*fn)(void *), void *data)
{
struct mc_buffer *b = &__get_cpu_var(mc_buffer);
struct callback *cb;
if (b->cbidx == MC_BATCH)
xen_mc_flush();
cb = &b->callbacks[b->cbidx++];
cb->fn = fn;
cb->data = data;
}

3
arch/x86/xen/multicalls.h
View file

@ -42,4 +42,7 @@ static inline void xen_mc_issue(unsigned mode)
local_irq_restore(x86_read_percpu(xen_mc_irq_flags));
}
/* Set up a callback to be called when the current batch is flushed */
void xen_mc_callback(void (*fn)(void *), void *data);
#endif /* _XEN_MULTICALLS_H */