kvmppc_init_hostwide() builds the hostwide L0-stats guest-state message and
buffer with kvmppc_gsm_new() and kvmppc_gsb_new() while holding
lock_l0_stats, which is taken with spin_lock_irqsave(). Both helpers
allocate with GFP_KERNEL (and kvmppc_gsb_new() does a further GFP_KERNEL
allocation internally), so they can sleep in atomic context, triggering
"BUG: sleeping function called from invalid context" under
CONFIG_DEBUG_ATOMIC_SLEEP.
lock_l0_stats is a spinlock because it also serializes the PMU ->read path
(kvmppc_pmu_event_update()), so it cannot be turned into a mutex. Build the
message and buffer in local variables outside the lock and only take the
lock to publish them, rechecking for a concurrent registration.
Fixes: f0c9c49c5067 ("powerpc/kvm-hv-pmu: Implement GSB message-ops for
hostwide counters")
Cc: [email protected]
Signed-off-by: Hyunjung Ko <[email protected]>
---
arch/powerpc/perf/kvm-hv-pmu.c | 70 ++++++++++++++++++++++++++----------------
1 file changed, 42 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/perf/kvm-hv-pmu.c b/arch/powerpc/perf/kvm-hv-pmu.c
index aa72b96b5a8c..deba59cbe234 100644
--- a/arch/powerpc/perf/kvm-hv-pmu.c
+++ b/arch/powerpc/perf/kvm-hv-pmu.c
@@ -314,53 +314,67 @@ static struct kvmppc_gs_msg_ops gsb_ops_l0_stats = {
static int kvmppc_init_hostwide(void)
{
- int rc = 0;
+ struct kvmppc_gs_msg *gsm;
+ struct kvmppc_gs_buff *gsb;
unsigned long flags;
+ int rc;
spin_lock_irqsave(&lock_l0_stats, flags);
-
/* already registered ? */
if (gsm_l0_stats) {
- rc = 0;
- goto out;
+ spin_unlock_irqrestore(&lock_l0_stats, flags);
+ return 0;
}
+ spin_unlock_irqrestore(&lock_l0_stats, flags);
+
+ /*
+ * kvmppc_gsm_new() and kvmppc_gsb_new() allocate with GFP_KERNEL and
+ * may sleep, so build the message and buffer outside lock_l0_stats,
+ * which is a spinlock (it also serializes the PMU ->read path), and
+ * only take the lock to publish them.
+ */
/* setup the Guest state message/buffer to talk to L0 */
- gsm_l0_stats = kvmppc_gsm_new(&gsb_ops_l0_stats, &l0_stats,
- GSM_SEND, GFP_KERNEL);
- if (!gsm_l0_stats) {
- rc = -ENOMEM;
- goto out;
- }
+ gsm = kvmppc_gsm_new(&gsb_ops_l0_stats, &l0_stats, GSM_SEND,
GFP_KERNEL);
+ if (!gsm)
+ return -ENOMEM;
/* Populate the Idents */
- kvmppc_gsm_include(gsm_l0_stats, KVMPPC_GSID_L0_GUEST_HEAP);
- kvmppc_gsm_include(gsm_l0_stats, KVMPPC_GSID_L0_GUEST_HEAP_MAX);
- kvmppc_gsm_include(gsm_l0_stats, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE);
- kvmppc_gsm_include(gsm_l0_stats, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX);
- kvmppc_gsm_include(gsm_l0_stats, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM);
+ kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_HEAP);
+ kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_HEAP_MAX);
+ kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE);
+ kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX);
+ kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM);
/* allocate GSB. Guest/Vcpu Id is ignored */
- gsb_l0_stats = kvmppc_gsb_new(kvmppc_gsm_size(gsm_l0_stats), 0, 0,
- GFP_KERNEL);
- if (!gsb_l0_stats) {
+ gsb = kvmppc_gsb_new(kvmppc_gsm_size(gsm), 0, 0, GFP_KERNEL);
+ if (!gsb) {
rc = -ENOMEM;
- goto out;
+ goto free_gsm;
}
/* ask the ops to fill in the info */
- rc = kvmppc_gsm_fill_info(gsm_l0_stats, gsb_l0_stats);
+ rc = kvmppc_gsm_fill_info(gsm, gsb);
+ if (rc)
+ goto free_gsb;
-out:
- if (rc) {
- if (gsm_l0_stats)
- kvmppc_gsm_free(gsm_l0_stats);
- if (gsb_l0_stats)
- kvmppc_gsb_free(gsb_l0_stats);
- gsm_l0_stats = NULL;
- gsb_l0_stats = NULL;
+ spin_lock_irqsave(&lock_l0_stats, flags);
+ if (gsm_l0_stats) {
+ /* raced with another CPU; use the existing registration */
+ spin_unlock_irqrestore(&lock_l0_stats, flags);
+ rc = 0;
+ goto free_gsb;
}
+ gsm_l0_stats = gsm;
+ gsb_l0_stats = gsb;
spin_unlock_irqrestore(&lock_l0_stats, flags);
+
+ return 0;
+
+free_gsb:
+ kvmppc_gsb_free(gsb);
+free_gsm:
+ kvmppc_gsm_free(gsm);
return rc;
}
--
2.43.0
