drm/v3d: Disable interrupts before resetting the GPU

Currently, an interrupt can be triggered during a GPU reset, which can
lead to GPU hangs and NULL pointer dereference in an interrupt context
as shown in the following trace:

 [  314.035040] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000c0
 [  314.043822] Mem abort info:
 [  314.046606]   ESR = 0x0000000096000005
 [  314.050347]   EC = 0x25: DABT (current EL), IL = 32 bits
 [  314.055651]   SET = 0, FnV = 0
 [  314.058695]   EA = 0, S1PTW = 0
 [  314.061826]   FSC = 0x05: level 1 translation fault
 [  314.066694] Data abort info:
 [  314.069564]   ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
 [  314.075039]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
 [  314.080080]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
 [  314.085382] user pgtable: 4k pages, 39-bit VAs, pgdp=0000000102728000
 [  314.091814] [00000000000000c0] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
 [  314.100511] Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
 [  314.106770] Modules linked in: v3d i2c_brcmstb vc4 snd_soc_hdmi_codec gpu_sched drm_shmem_helper drm_display_helper cec drm_dma_helper drm_kms_helper drm drm_panel_orientation_quirks snd_soc_core snd_compress snd_pcm_dmaengine snd_pcm snd_timer snd backlight
 [  314.129654] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.25+rpt-rpi-v8 #1  Debian 1:6.12.25-1+rpt1
 [  314.139388] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
 [  314.145211] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 [  314.152165] pc : v3d_irq+0xec/0x2e0 [v3d]
 [  314.156187] lr : v3d_irq+0xe0/0x2e0 [v3d]
 [  314.160198] sp : ffffffc080003ea0
 [  314.163502] x29: ffffffc080003ea0 x28: ffffffec1f184980 x27: 021202b000000000
 [  314.170633] x26: ffffffec1f17f630 x25: ffffff8101372000 x24: ffffffec1f17d9f0
 [  314.177764] x23: 000000000000002a x22: 000000000000002a x21: ffffff8103252000
 [  314.184895] x20: 0000000000000001 x19: 00000000deadbeef x18: 0000000000000000
 [  314.192026] x17: ffffff94e51d2000 x16: ffffffec1dac3cb0 x15: c306000000000000
 [  314.199156] x14: 0000000000000000 x13: b2fc982e03cc5168 x12: 0000000000000001
 [  314.206286] x11: ffffff8103f8bcc0 x10: ffffffec1f196868 x9 : ffffffec1dac3874
 [  314.213416] x8 : 0000000000000000 x7 : 0000000000042a3a x6 : ffffff810017a180
 [  314.220547] x5 : ffffffec1ebad400 x4 : ffffffec1ebad320 x3 : 00000000000bebeb
 [  314.227677] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
 [  314.234807] Call trace:
 [  314.237243]  v3d_irq+0xec/0x2e0 [v3d]
 [  314.240906]  __handle_irq_event_percpu+0x58/0x218
 [  314.245609]  handle_irq_event+0x54/0xb8
 [  314.249439]  handle_fasteoi_irq+0xac/0x240
 [  314.253527]  handle_irq_desc+0x48/0x68
 [  314.257269]  generic_handle_domain_irq+0x24/0x38
 [  314.261879]  gic_handle_irq+0x48/0xd8
 [  314.265533]  call_on_irq_stack+0x24/0x58
 [  314.269448]  do_interrupt_handler+0x88/0x98
 [  314.273624]  el1_interrupt+0x34/0x68
 [  314.277193]  el1h_64_irq_handler+0x18/0x28
 [  314.281281]  el1h_64_irq+0x64/0x68
 [  314.284673]  default_idle_call+0x3c/0x168
 [  314.288675]  do_idle+0x1fc/0x230
 [  314.291895]  cpu_startup_entry+0x3c/0x50
 [  314.295810]  rest_init+0xe4/0xf0
 [  314.299030]  start_kernel+0x5e8/0x790
 [  314.302684]  __primary_switched+0x80/0x90
 [  314.306691] Code: 940029eb 360ffc13 f9442ea0 52800001 (f9406017)
 [  314.312775] ---[ end trace 0000000000000000 ]---
 [  314.317384] Kernel panic - not syncing: Oops: Fatal exception in interrupt
 [  314.324249] SMP: stopping secondary CPUs
 [  314.328167] Kernel Offset: 0x2b9da00000 from 0xffffffc080000000
 [  314.334076] PHYS_OFFSET: 0x0
 [  314.336946] CPU features: 0x08,00002013,c0200000,0200421b
 [  314.342337] Memory Limit: none
 [  314.345382] ---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]---

Before resetting the GPU, it's necessary to disable all interrupts and
deal with any interrupt handler still in-flight. Otherwise, the GPU might
reset with jobs still running, or yet, an interrupt could be handled
during the reset.

Cc: [email protected]
Fixes: 57692c9 ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+")
Reviewed-by: Juan A. Suarez <[email protected]>
Reviewed-by: Iago Toral Quiroga <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maíra Canal <[email protected]>

Author: mairacanal

drivers/gpu/drm/v3d/v3d_drv.h

@@ -101,6 +101,12 @@ enum v3d_gen {
 	V3D_GEN_71 = 71,
 };
 
+enum v3d_irq {
+	V3D_CORE_IRQ,
+	V3D_HUB_IRQ,
+	V3D_MAX_IRQS,
+};
+
 struct v3d_dev {
 	struct drm_device drm;
 
@@ -112,6 +118,8 @@ struct v3d_dev {
 
 	bool single_irq_line;
 
+	int irq[V3D_MAX_IRQS];
+
 	struct v3d_perfmon_info perfmon_info;
 
 	void __iomem *hub_regs;

drivers/gpu/drm/v3d/v3d_gem.c

@@ -134,6 +134,8 @@ v3d_reset(struct v3d_dev *v3d)
 	if (false)
 		v3d_idle_axi(v3d, 0);
 
+	v3d_irq_disable(v3d);
+
 	v3d_idle_gca(v3d);
 	v3d_reset_sms(v3d);
 	v3d_reset_v3d(v3d);

drivers/gpu/drm/v3d/v3d_irq.c

@@ -260,7 +260,7 @@ v3d_hub_irq(int irq, void *arg)
 int
 v3d_irq_init(struct v3d_dev *v3d)
 {
-	int irq1, ret, core;
+	int irq, ret, core;
 
 	INIT_WORK(&v3d->overflow_mem_work, v3d_overflow_mem_work);
 
@@ -271,26 +271,37 @@ v3d_irq_init(struct v3d_dev *v3d)
 		V3D_CORE_WRITE(core, V3D_CTL_INT_CLR, V3D_CORE_IRQS(v3d->ver));
 	V3D_WRITE(V3D_HUB_INT_CLR, V3D_HUB_IRQS(v3d->ver));
 
-	irq1 = platform_get_irq_optional(v3d_to_pdev(v3d), 1);
-	if (irq1 == -EPROBE_DEFER)
-		return irq1;
-	if (irq1 > 0) {
-		ret = devm_request_irq(v3d->drm.dev, irq1,
+	irq = platform_get_irq_optional(v3d_to_pdev(v3d), 1);
+	if (irq == -EPROBE_DEFER)
+		return irq;
+	if (irq > 0) {
+		v3d->irq[V3D_CORE_IRQ] = irq;
+
+		ret = devm_request_irq(v3d->drm.dev, v3d->irq[V3D_CORE_IRQ],
 				       v3d_irq, IRQF_SHARED,
 				       "v3d_core0", v3d);
 		if (ret)
 			goto fail;
-		ret = devm_request_irq(v3d->drm.dev,
-				       platform_get_irq(v3d_to_pdev(v3d), 0),
+
+		irq = platform_get_irq(v3d_to_pdev(v3d), 0);
+		if (irq < 0)
+			return irq;
+		v3d->irq[V3D_HUB_IRQ] = irq;
+
+		ret = devm_request_irq(v3d->drm.dev, v3d->irq[V3D_HUB_IRQ],
 				       v3d_hub_irq, IRQF_SHARED,
 				       "v3d_hub", v3d);
 		if (ret)
 			goto fail;
 	} else {
 		v3d->single_irq_line = true;
 
-		ret = devm_request_irq(v3d->drm.dev,
-				       platform_get_irq(v3d_to_pdev(v3d), 0),
+		irq = platform_get_irq(v3d_to_pdev(v3d), 0);
+		if (irq < 0)
+			return irq;
+		v3d->irq[V3D_CORE_IRQ] = irq;
+
+		ret = devm_request_irq(v3d->drm.dev, v3d->irq[V3D_CORE_IRQ],
 				       v3d_irq, IRQF_SHARED,
 				       "v3d", v3d);
 		if (ret)
@@ -331,6 +342,12 @@ v3d_irq_disable(struct v3d_dev *v3d)
 		V3D_CORE_WRITE(core, V3D_CTL_INT_MSK_SET, ~0);
 	V3D_WRITE(V3D_HUB_INT_MSK_SET, ~0);
 
+	/* Finish any interrupt handler still in flight. */
+	for (int i = 0; i < V3D_MAX_IRQS; i++) {
+		if (v3d->irq[i])
+			synchronize_irq(v3d->irq[i]);
+	}
+
 	/* Clear any pending interrupts we might have left. */
 	for (core = 0; core < v3d->cores; core++)
 		V3D_CORE_WRITE(core, V3D_CTL_INT_CLR, V3D_CORE_IRQS(v3d->ver));