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Date: Thu, 13 Jun 2024 14:13:35 +0000
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Subject: [PATCH v2 2/2] misc: Register a PPI for the vcpu stall detection
 virtual device
From: Sebastian Ene <sebastianene@google.com>
To: arnd@arndb.de, gregkh@linuxfoundation.org, will@kernel.org, maz@kernel.org, 
	Rob Herring <robh+dt@kernel.org>, Dragan Cvetic <dragan.cvetic@xilinx.com>, 
	Guenter Roeck <linux@roeck-us.net>
Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, 
	kernel-team@android.com, Sebastian Ene <sebastianene@google.com>
Content-Type: text/plain; charset="UTF-8"

Request a PPI for each vCPU during probe which will be used by the host
to communicate a stall detected event on the vCPU. When the host raises
this interrupt from the virtual machine monitor, the guest is expected to
handle the interrupt and panic.

Signed-off-by: Sebastian Ene <sebastianene@google.com>
---
 drivers/misc/vcpu_stall_detector.c | 31 ++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/vcpu_stall_detector.c b/drivers/misc/vcpu_stall_detector.c
index e2015c87f03f..41b8c2119e20 100644
--- a/drivers/misc/vcpu_stall_detector.c
+++ b/drivers/misc/vcpu_stall_detector.c
@@ -32,6 +32,7 @@
 struct vcpu_stall_detect_config {
 	u32 clock_freq_hz;
 	u32 stall_timeout_sec;
+	int ppi_irq;
 
 	void __iomem *membase;
 	struct platform_device *dev;
@@ -77,6 +78,12 @@ vcpu_stall_detect_timer_fn(struct hrtimer *hrtimer)
 	return HRTIMER_RESTART;
 }
 
+static irqreturn_t vcpu_stall_detector_irq(int irq, void *dev)
+{
+	panic("vCPU stall detector");
+	return IRQ_HANDLED;
+}
+
 static int start_stall_detector_cpu(unsigned int cpu)
 {
 	u32 ticks, ping_timeout_ms;
@@ -132,7 +139,7 @@ static int stop_stall_detector_cpu(unsigned int cpu)
 
 static int vcpu_stall_detect_probe(struct platform_device *pdev)
 {
-	int ret;
+	int ret, irq;
 	struct resource *r;
 	void __iomem *membase;
 	u32 clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
@@ -169,9 +176,22 @@ static int vcpu_stall_detect_probe(struct platform_device *pdev)
 	vcpu_stall_config = (struct vcpu_stall_detect_config) {
 		.membase		= membase,
 		.clock_freq_hz		= clock_freq_hz,
-		.stall_timeout_sec	= stall_timeout_sec
+		.stall_timeout_sec	= stall_timeout_sec,
+		.ppi_irq		= -1,
 	};
 
+	irq = platform_get_irq_optional(pdev, 0);
+	if (irq > 0) {
+		ret = request_percpu_irq(irq,
+					 vcpu_stall_detector_irq,
+					 "vcpu_stall_detector",
+					 vcpu_stall_detectors);
+		if (ret)
+			goto err;
+
+		vcpu_stall_config.ppi_irq = irq;
+	}
+
 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
 				"virt/vcpu_stall_detector:online",
 				start_stall_detector_cpu,
@@ -184,6 +204,9 @@ static int vcpu_stall_detect_probe(struct platform_device *pdev)
 	vcpu_stall_config.hp_online = ret;
 	return 0;
 err:
+	if (vcpu_stall_config.ppi_irq > 0)
+		free_percpu_irq(vcpu_stall_config.ppi_irq,
+				vcpu_stall_detectors);
 	return ret;
 }
 
@@ -193,6 +216,10 @@ static void vcpu_stall_detect_remove(struct platform_device *pdev)
 
 	cpuhp_remove_state(vcpu_stall_config.hp_online);
 
+	if (vcpu_stall_config.ppi_irq > 0)
+		free_percpu_irq(vcpu_stall_config.ppi_irq,
+				vcpu_stall_detectors);
+
 	for_each_possible_cpu(cpu)
 		stop_stall_detector_cpu(cpu);
 }
-- 
2.45.2.505.gda0bf45e8d-goog