From: zhenwei pi Date: Sun, 10 Jan 2021 11:53:57 +0000 (+0800) Subject: misc: pvpanic: introduce device capability X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=487709fa1be2f27aa8e7de6c60587b4302a21467;p=linux.git 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: zhenwei pi Reviewed-by: Paolo Bonzini Link: https://lore.kernel.org/r/20210110115358.79100-2-pizhenwei@bytedance.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/Documentation/ABI/testing/sysfs-bus-pci-devices-pvpanic b/Documentation/ABI/testing/sysfs-bus-pci-devices-pvpanic new file mode 100644 index 0000000000000..79b7dc31cd55c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-pci-devices-pvpanic @@ -0,0 +1,12 @@ +What: /sys/devices/pci0000:00/*/QEMU0001:00/capability +Date: Jan 2021 +Contact: zhenwei pi +Description: + Read-only attribute. Capabilities of pvpanic device which + are supported by QEMU. + + Format: %x. + + Detailed bit definition refers to section + from pvpanic device specification: + https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/specs/pvpanic.txt diff --git a/drivers/misc/pvpanic.c b/drivers/misc/pvpanic.c index 41cab297d66e7..80cdfa8f951a9 100644 --- a/drivers/misc/pvpanic.c +++ b/drivers/misc/pvpanic.c @@ -19,6 +19,20 @@ #include 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 "); MODULE_DESCRIPTION("pvpanic device driver"); @@ -27,7 +41,8 @@ MODULE_LICENSE("GPL"); static void pvpanic_send_event(unsigned int event) { - iowrite8(event, base); + if (event & capability) + iowrite8(event, base); } static int @@ -73,8 +88,12 @@ static int pvpanic_mmio_probe(struct platform_device *pdev) return -EINVAL; } - atomic_notifier_chain_register(&panic_notifier_list, - &pvpanic_panic_nb); + /* initlize capability by RDPT */ + capability &= ioread8(base); + + if (capability) + atomic_notifier_chain_register(&panic_notifier_list, + &pvpanic_panic_nb); return 0; } @@ -82,8 +101,9 @@ static int pvpanic_mmio_probe(struct platform_device *pdev) static int pvpanic_mmio_remove(struct platform_device *pdev) { - atomic_notifier_chain_unregister(&panic_notifier_list, - &pvpanic_panic_nb); + if (capability) + atomic_notifier_chain_unregister(&panic_notifier_list, + &pvpanic_panic_nb); return 0; } @@ -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,