ice: fix 'scheduling while atomic' on aux critical err interrupt

There's a kernel BUG splat on processing aux critical error
interrupts in ice_misc_intr():

[ 2100.917085] BUG: scheduling while atomic: swapper/15/0/0x00010000
...
[ 2101.060770] Call Trace:
[ 2101.063229]  <IRQ>
[ 2101.065252]  dump_stack+0x41/0x60
[ 2101.068587]  __schedule_bug.cold.100+0x4c/0x58
[ 2101.073060]  __schedule+0x6a4/0x830
[ 2101.076570]  schedule+0x35/0xa0
[ 2101.079727]  schedule_preempt_disabled+0xa/0x10
[ 2101.084284]  __mutex_lock.isra.7+0x310/0x420
[ 2101.088580]  ? ice_misc_intr+0x201/0x2e0 [ice]
[ 2101.093078]  ice_send_event_to_aux+0x25/0x70 [ice]
[ 2101.097921]  ice_misc_intr+0x220/0x2e0 [ice]
[ 2101.102232]  __handle_irq_event_percpu+0x40/0x180
[ 2101.106965]  handle_irq_event_percpu+0x30/0x80
[ 2101.111434]  handle_irq_event+0x36/0x53
[ 2101.115292]  handle_edge_irq+0x82/0x190
[ 2101.119148]  handle_irq+0x1c/0x30
[ 2101.122480]  do_IRQ+0x49/0xd0
[ 2101.125465]  common_interrupt+0xf/0xf
[ 2101.129146]  </IRQ>
...

As Andrew correctly mentioned previously[0], the following call
ladder happens:

ice_misc_intr() <- hardirq
  ice_send_event_to_aux()
    device_lock()
      mutex_lock()
        might_sleep()
          might_resched() <- oops

Add a new PF state bit which indicates that an aux critical error
occurred and serve it in ice_service_task() in process context.
The new ice_pf::oicr_err_reg is read-write in both hardirq and
process contexts, but only 3 bits of non-critical data probably
aren't worth explicit synchronizing (and they're even in the same
byte [31:24]).

[0] https://lore.kernel.org/all/YeSRUVmrdmlUXHDn@lunn.ch

Fixes: 348048e7 ("ice: Implement iidc operations")
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Tested-by: Michal Kubiak <michal.kubiak@intel.com>
Acked-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/intel/ice/ice.h

@@ -290,6 +290,7 @@ enum ice_pf_state {
 	ICE_LINK_DEFAULT_OVERRIDE_PENDING,
 	ICE_PHY_INIT_COMPLETE,
 	ICE_FD_VF_FLUSH_CTX,		/* set at FD Rx IRQ or timeout */
+	ICE_AUX_ERR_PENDING,
 	ICE_STATE_NBITS		/* must be last */
 };
 
@@ -559,6 +560,7 @@ struct ice_pf {
 	wait_queue_head_t reset_wait_queue;
 
 	u32 hw_csum_rx_error;
+	u32 oicr_err_reg;
 	u16 oicr_idx;		/* Other interrupt cause MSIX vector index */
 	u16 num_avail_sw_msix;	/* remaining MSIX SW vectors left unclaimed */
 	u16 max_pf_txqs;	/* Total Tx queues PF wide */

drivers/net/ethernet/intel/ice/ice_main.c

@@ -2255,6 +2255,19 @@ static void ice_service_task(struct work_struct *work)
 		return;
 	}
 
+	if (test_and_clear_bit(ICE_AUX_ERR_PENDING, pf->state)) {
+		struct iidc_event *event;
+
+		event = kzalloc(sizeof(*event), GFP_KERNEL);
+		if (event) {
+			set_bit(IIDC_EVENT_CRIT_ERR, event->type);
+			/* report the entire OICR value to AUX driver */
+			swap(event->reg, pf->oicr_err_reg);
+			ice_send_event_to_aux(pf, event);
+			kfree(event);
+		}
+	}
+
 	if (test_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags)) {
 		/* Plug aux device per request */
 		ice_plug_aux_dev(pf);
@@ -3041,17 +3054,9 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
 
 #define ICE_AUX_CRIT_ERR (PFINT_OICR_PE_CRITERR_M | PFINT_OICR_HMC_ERR_M | PFINT_OICR_PE_PUSH_M)
 	if (oicr & ICE_AUX_CRIT_ERR) {
-		struct iidc_event *event;
-
+		pf->oicr_err_reg |= oicr;
+		set_bit(ICE_AUX_ERR_PENDING, pf->state);
 		ena_mask &= ~ICE_AUX_CRIT_ERR;
-		event = kzalloc(sizeof(*event), GFP_ATOMIC);
-		if (event) {
-			set_bit(IIDC_EVENT_CRIT_ERR, event->type);
-			/* report the entire OICR value to AUX driver */
-			event->reg = oicr;
-			ice_send_event_to_aux(pf, event);
-			kfree(event);
-		}
 	}
 
 	/* Report any remaining unexpected interrupts */