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xen: fix multicall debug data referencing

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The recent adding of multicall debug mixed up the referencing of
the debug data. A __percpu tagged pointer can't be initialized with a
plain pointer, so use another percpu variable for the pointer and set
it on each new cpu via a function.

Fixes: 942d917cb9 ("xen: make multicall debug boot time selectable")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407151106.5s7Mnfpz-lkp@intel.com/
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2024-07-15 09:47:08 +02:00
parent 9fe6a8c5b2
commit 368990a7fe
3 changed files with 16 additions and 7 deletions
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19
arch/x86/xen/multicalls.c
View File

@ -54,8 +54,9 @@ struct mc_debug_data {
static DEFINE_PER_CPU(struct mc_buffer, mc_buffer);
static struct mc_debug_data mc_debug_data_early __initdata;
static struct mc_debug_data __percpu *mc_debug_data __refdata =
static DEFINE_PER_CPU(struct mc_debug_data *, mc_debug_data) =
&mc_debug_data_early;
static struct mc_debug_data __percpu *mc_debug_data_ptr;
DEFINE_PER_CPU(unsigned long, xen_mc_irq_flags);
static struct static_key mc_debug __ro_after_init;
@ -70,16 +71,20 @@ static int __init xen_parse_mc_debug(char *arg)
}
early_param("xen_mc_debug", xen_parse_mc_debug);
void mc_percpu_init(unsigned int cpu)
{
per_cpu(mc_debug_data, cpu) = per_cpu_ptr(mc_debug_data_ptr, cpu);
}
static int __init mc_debug_enable(void)
{
struct mc_debug_data __percpu *mcdb;
unsigned long flags;
if (!mc_debug_enabled)
return 0;
mcdb = alloc_percpu(struct mc_debug_data);
if (!mcdb) {
mc_debug_data_ptr = alloc_percpu(struct mc_debug_data);
if (!mc_debug_data_ptr) {
pr_err("xen_mc_debug inactive\n");
static_key_slow_dec(&mc_debug);
return -ENOMEM;
@ -88,7 +93,7 @@ static int __init mc_debug_enable(void)
/* Be careful when switching to percpu debug data. */
local_irq_save(flags);
xen_mc_flush();
mc_debug_data = mcdb;
mc_percpu_init(0);
local_irq_restore(flags);
pr_info("xen_mc_debug active\n");
@ -150,7 +155,7 @@ void xen_mc_flush(void)
trace_xen_mc_flush(b->mcidx, b->argidx, b->cbidx);
if (static_key_false(&mc_debug)) {
mcdb = this_cpu_ptr(mc_debug_data);
mcdb = __this_cpu_read(mc_debug_data);
memcpy(mcdb->entries, b->entries,
b->mcidx * sizeof(struct multicall_entry));
}
@ -230,7 +235,7 @@ struct multicall_space __xen_mc_entry(size_t args)
ret.mc = &b->entries[b->mcidx];
if (static_key_false(&mc_debug)) {
struct mc_debug_data *mcdb = this_cpu_ptr(mc_debug_data);
struct mc_debug_data *mcdb = __this_cpu_read(mc_debug_data);
mcdb->caller[b->mcidx] = __builtin_return_address(0);
mcdb->argsz[b->mcidx] = args;

1
arch/x86/xen/smp_pv.c
View File

@ -305,6 +305,7 @@ static int xen_pv_kick_ap(unsigned int cpu, struct task_struct *idle)
return rc;
xen_pmu_init(cpu);
mc_percpu_init(cpu);
/*
* Why is this a BUG? If the hypercall fails then everything can be

3
arch/x86/xen/xen-ops.h
View File

@ -257,6 +257,9 @@ void xen_mc_callback(void (*fn)(void *), void *data);
*/
struct multicall_space xen_mc_extend_args(unsigned long op, size_t arg_size);
/* Do percpu data initialization for multicalls. */
void mc_percpu_init(unsigned int cpu);
extern bool is_xen_pmu;
irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id);