From 487709fa1be2f27aa8e7de6c60587b4302a21467 Mon Sep 17 00:00:00 2001 From: zhenwei pi Date: Sun, 10 Jan 2021 19:53:57 +0800 Subject: [PATCH] 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 --- .../ABI/testing/sysfs-bus-pci-devices-pvpanic | 12 +++++++++ drivers/misc/pvpanic.c | 31 ++++++++++++++++++---- 2 files changed, 38 insertions(+), 5 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-devices-pvpanic 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 0000000..79b7dc3 --- /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 41cab29..80cdfa8 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, -- 2.7.4