mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-11 13:04:03 +08:00
c99608637e
We can't call the callbacks after enabling interrupts, as we may get a nested multicall call, which would cause a great deal of havok. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
284 lines
6.2 KiB
C
284 lines
6.2 KiB
C
/*
|
|
* Xen hypercall batching.
|
|
*
|
|
* Xen allows multiple hypercalls to be issued at once, using the
|
|
* multicall interface. This allows the cost of trapping into the
|
|
* hypervisor to be amortized over several calls.
|
|
*
|
|
* This file implements a simple interface for multicalls. There's a
|
|
* per-cpu buffer of outstanding multicalls. When you want to queue a
|
|
* multicall for issuing, you can allocate a multicall slot for the
|
|
* call and its arguments, along with storage for space which is
|
|
* pointed to by the arguments (for passing pointers to structures,
|
|
* etc). When the multicall is actually issued, all the space for the
|
|
* commands and allocated memory is freed for reuse.
|
|
*
|
|
* Multicalls are flushed whenever any of the buffers get full, or
|
|
* when explicitly requested. There's no way to get per-multicall
|
|
* return results back. It will BUG if any of the multicalls fail.
|
|
*
|
|
* Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
|
|
*/
|
|
#include <linux/percpu.h>
|
|
#include <linux/hardirq.h>
|
|
#include <linux/debugfs.h>
|
|
|
|
#include <asm/xen/hypercall.h>
|
|
|
|
#include "multicalls.h"
|
|
#include "debugfs.h"
|
|
|
|
#define MC_BATCH 32
|
|
|
|
#define MC_DEBUG 1
|
|
|
|
#define MC_ARGS (MC_BATCH * 16)
|
|
|
|
|
|
struct mc_buffer {
|
|
struct multicall_entry entries[MC_BATCH];
|
|
#if MC_DEBUG
|
|
struct multicall_entry debug[MC_BATCH];
|
|
void *caller[MC_BATCH];
|
|
#endif
|
|
unsigned char args[MC_ARGS];
|
|
struct callback {
|
|
void (*fn)(void *);
|
|
void *data;
|
|
} callbacks[MC_BATCH];
|
|
unsigned mcidx, argidx, cbidx;
|
|
};
|
|
|
|
static DEFINE_PER_CPU(struct mc_buffer, mc_buffer);
|
|
DEFINE_PER_CPU(unsigned long, xen_mc_irq_flags);
|
|
|
|
/* flush reasons 0- slots, 1- args, 2- callbacks */
|
|
enum flush_reasons
|
|
{
|
|
FL_SLOTS,
|
|
FL_ARGS,
|
|
FL_CALLBACKS,
|
|
|
|
FL_N_REASONS
|
|
};
|
|
|
|
#ifdef CONFIG_XEN_DEBUG_FS
|
|
#define NHYPERCALLS 40 /* not really */
|
|
|
|
static struct {
|
|
unsigned histo[MC_BATCH+1];
|
|
|
|
unsigned issued;
|
|
unsigned arg_total;
|
|
unsigned hypercalls;
|
|
unsigned histo_hypercalls[NHYPERCALLS];
|
|
|
|
unsigned flush[FL_N_REASONS];
|
|
} mc_stats;
|
|
|
|
static u8 zero_stats;
|
|
|
|
static inline void check_zero(void)
|
|
{
|
|
if (unlikely(zero_stats)) {
|
|
memset(&mc_stats, 0, sizeof(mc_stats));
|
|
zero_stats = 0;
|
|
}
|
|
}
|
|
|
|
static void mc_add_stats(const struct mc_buffer *mc)
|
|
{
|
|
int i;
|
|
|
|
check_zero();
|
|
|
|
mc_stats.issued++;
|
|
mc_stats.hypercalls += mc->mcidx;
|
|
mc_stats.arg_total += mc->argidx;
|
|
|
|
mc_stats.histo[mc->mcidx]++;
|
|
for(i = 0; i < mc->mcidx; i++) {
|
|
unsigned op = mc->entries[i].op;
|
|
if (op < NHYPERCALLS)
|
|
mc_stats.histo_hypercalls[op]++;
|
|
}
|
|
}
|
|
|
|
static void mc_stats_flush(enum flush_reasons idx)
|
|
{
|
|
check_zero();
|
|
|
|
mc_stats.flush[idx]++;
|
|
}
|
|
|
|
#else /* !CONFIG_XEN_DEBUG_FS */
|
|
|
|
static inline void mc_add_stats(const struct mc_buffer *mc)
|
|
{
|
|
}
|
|
|
|
static inline void mc_stats_flush(enum flush_reasons idx)
|
|
{
|
|
}
|
|
#endif /* CONFIG_XEN_DEBUG_FS */
|
|
|
|
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());
|
|
|
|
/* Disable interrupts in case someone comes in and queues
|
|
something in the middle */
|
|
local_irq_save(flags);
|
|
|
|
mc_add_stats(b);
|
|
|
|
if (b->mcidx) {
|
|
#if MC_DEBUG
|
|
memcpy(b->debug, b->entries,
|
|
b->mcidx * sizeof(struct multicall_entry));
|
|
#endif
|
|
|
|
if (HYPERVISOR_multicall(b->entries, b->mcidx) != 0)
|
|
BUG();
|
|
for (i = 0; i < b->mcidx; i++)
|
|
if (b->entries[i].result < 0)
|
|
ret++;
|
|
|
|
#if MC_DEBUG
|
|
if (ret) {
|
|
printk(KERN_ERR "%d multicall(s) failed: cpu %d\n",
|
|
ret, smp_processor_id());
|
|
dump_stack();
|
|
for (i = 0; i < b->mcidx; i++) {
|
|
printk(KERN_DEBUG " call %2d/%d: op=%lu arg=[%lx] result=%ld\t%pF\n",
|
|
i+1, b->mcidx,
|
|
b->debug[i].op,
|
|
b->debug[i].args[0],
|
|
b->entries[i].result,
|
|
b->caller[i]);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
b->mcidx = 0;
|
|
b->argidx = 0;
|
|
} else
|
|
BUG_ON(b->argidx != 0);
|
|
|
|
for (i = 0; i < b->cbidx; i++) {
|
|
struct callback *cb = &b->callbacks[i];
|
|
|
|
(*cb->fn)(cb->data);
|
|
}
|
|
b->cbidx = 0;
|
|
|
|
local_irq_restore(flags);
|
|
|
|
WARN_ON(ret);
|
|
}
|
|
|
|
struct multicall_space __xen_mc_entry(size_t args)
|
|
{
|
|
struct mc_buffer *b = &__get_cpu_var(mc_buffer);
|
|
struct multicall_space ret;
|
|
unsigned argidx = roundup(b->argidx, sizeof(u64));
|
|
|
|
BUG_ON(preemptible());
|
|
BUG_ON(b->argidx > MC_ARGS);
|
|
|
|
if (b->mcidx == MC_BATCH ||
|
|
(argidx + args) > MC_ARGS) {
|
|
mc_stats_flush(b->mcidx == MC_BATCH ? FL_SLOTS : FL_ARGS);
|
|
xen_mc_flush();
|
|
argidx = roundup(b->argidx, sizeof(u64));
|
|
}
|
|
|
|
ret.mc = &b->entries[b->mcidx];
|
|
#ifdef MC_DEBUG
|
|
b->caller[b->mcidx] = __builtin_return_address(0);
|
|
#endif
|
|
b->mcidx++;
|
|
ret.args = &b->args[argidx];
|
|
b->argidx = argidx + args;
|
|
|
|
BUG_ON(b->argidx > MC_ARGS);
|
|
return ret;
|
|
}
|
|
|
|
struct multicall_space xen_mc_extend_args(unsigned long op, size_t size)
|
|
{
|
|
struct mc_buffer *b = &__get_cpu_var(mc_buffer);
|
|
struct multicall_space ret = { NULL, NULL };
|
|
|
|
BUG_ON(preemptible());
|
|
BUG_ON(b->argidx > MC_ARGS);
|
|
|
|
if (b->mcidx == 0)
|
|
return ret;
|
|
|
|
if (b->entries[b->mcidx - 1].op != op)
|
|
return ret;
|
|
|
|
if ((b->argidx + size) > MC_ARGS)
|
|
return ret;
|
|
|
|
ret.mc = &b->entries[b->mcidx - 1];
|
|
ret.args = &b->args[b->argidx];
|
|
b->argidx += size;
|
|
|
|
BUG_ON(b->argidx > MC_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) {
|
|
mc_stats_flush(FL_CALLBACKS);
|
|
xen_mc_flush();
|
|
}
|
|
|
|
cb = &b->callbacks[b->cbidx++];
|
|
cb->fn = fn;
|
|
cb->data = data;
|
|
}
|
|
|
|
#ifdef CONFIG_XEN_DEBUG_FS
|
|
|
|
static struct dentry *d_mc_debug;
|
|
|
|
static int __init xen_mc_debugfs(void)
|
|
{
|
|
struct dentry *d_xen = xen_init_debugfs();
|
|
|
|
if (d_xen == NULL)
|
|
return -ENOMEM;
|
|
|
|
d_mc_debug = debugfs_create_dir("multicalls", d_xen);
|
|
|
|
debugfs_create_u8("zero_stats", 0644, d_mc_debug, &zero_stats);
|
|
|
|
debugfs_create_u32("batches", 0444, d_mc_debug, &mc_stats.issued);
|
|
debugfs_create_u32("hypercalls", 0444, d_mc_debug, &mc_stats.hypercalls);
|
|
debugfs_create_u32("arg_total", 0444, d_mc_debug, &mc_stats.arg_total);
|
|
|
|
xen_debugfs_create_u32_array("batch_histo", 0444, d_mc_debug,
|
|
mc_stats.histo, MC_BATCH);
|
|
xen_debugfs_create_u32_array("hypercall_histo", 0444, d_mc_debug,
|
|
mc_stats.histo_hypercalls, NHYPERCALLS);
|
|
xen_debugfs_create_u32_array("flush_reasons", 0444, d_mc_debug,
|
|
mc_stats.flush, FL_N_REASONS);
|
|
|
|
return 0;
|
|
}
|
|
fs_initcall(xen_mc_debugfs);
|
|
|
|
#endif /* CONFIG_XEN_DEBUG_FS */
|