Commit 368990a7 authored by Juergen Gross's avatar Juergen Gross
Browse files

xen: fix multicall debug data referencing 



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: 942d917c ("xen: make multicall debug boot time selectable")
Reported-by: default avatarkernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407151106.5s7Mnfpz-lkp@intel.com/


Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
parent 9fe6a8c5

arch/x86/xen/multicalls.c

+12 −7
Original line number Diff line number Diff line
@@ -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;

arch/x86/xen/smp_pv.c

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/xen/xen-ops.h

+3 −0
Original line number Diff line number Diff line
@@ -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);