Commit 487709fa authored by zhenwei pi's avatar zhenwei pi Committed by Greg Kroah-Hartman
Browse files

misc: pvpanic: introduce device capability 

According to pvpanic spec:
https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/specs/pvpanic.txt



The guest should determine pvpanic capability by RDPT, so initialize
capability during device probing. There is no need to register panic
notifier callback function if no events supported.

Before sending event to host side, check capability firstly.

Suggested by Greg KH, use sysfs to expose capability to user space,
also add new sysfs attribute in document.

Signed-off-by: default avatarzhenwei pi <pizhenwei@bytedance.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20210110115358.79100-2-pizhenwei@bytedance.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8ba59e9d

Documentation/ABI/testing/sysfs-bus-pci-devices-pvpanic

0 → 100644
+12 −0
Original line number Diff line number Diff line 
What:		/sys/devices/pci0000:00/*/QEMU0001:00/capability

Date:		Jan 2021

Contact:	zhenwei pi <pizhenwei@bytedance.com>

Description:

		Read-only attribute. Capabilities of pvpanic device which

		are supported by QEMU.



		Format: %x.



		Detailed bit definition refers to section <Bit Definition>

		from pvpanic device specification:

		https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/specs/pvpanic.txt

drivers/misc/pvpanic.c

+26 −5
Original line number Diff line number Diff line
@@ -19,6 +19,20 @@ 
#include <uapi/misc/pvpanic.h>



static void __iomem *base;

static unsigned int capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED;



static ssize_t capability_show(struct device *dev,

			       struct device_attribute *attr, char *buf)

{

	return sysfs_emit(buf, "%x", capability);

}

static DEVICE_ATTR_RO(capability);



static struct attribute *pvpanic_dev_attrs[] = {

	&dev_attr_capability.attr,

	NULL

};

ATTRIBUTE_GROUPS(pvpanic_dev);



MODULE_AUTHOR("Hu Tao <hutao@cn.fujitsu.com>");

MODULE_DESCRIPTION("pvpanic device driver");
@@ -27,6 +41,7 @@ MODULE_LICENSE("GPL"); 
static void

pvpanic_send_event(unsigned int event)

{

	if (event & capability)

		iowrite8(event, base);

}
@@ -73,6 +88,10 @@ static int pvpanic_mmio_probe(struct platform_device *pdev) 
		return -EINVAL;

	}



	/* initlize capability by RDPT */

	capability &= ioread8(base);



	if (capability)

		atomic_notifier_chain_register(&panic_notifier_list,

					       &pvpanic_panic_nb);
@@ -82,6 +101,7 @@ static int pvpanic_mmio_probe(struct platform_device *pdev) 
static int pvpanic_mmio_remove(struct platform_device *pdev)

{



	if (capability)

		atomic_notifier_chain_unregister(&panic_notifier_list,

						 &pvpanic_panic_nb);
@@ -104,6 +124,7 @@ static struct platform_driver pvpanic_mmio_driver = { 
		.name = "pvpanic-mmio",

		.of_match_table = pvpanic_mmio_match,

		.acpi_match_table = pvpanic_device_ids,

		.dev_groups = pvpanic_dev_groups,

	},

	.probe = pvpanic_mmio_probe,

	.remove = pvpanic_mmio_remove,