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misc: pvpanic: introduce events device attribue 

Suggested by Paolo & Greg, add 'events' device attribute that can be
used to limit which capabilities the driver uses.

Finally, the pvpanic guest driver works by the limitation of both
device capability and user setting.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20210110115358.79100-3-pizhenwei@bytedance.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
zhenwei pi 2021-01-10 19:53:58 +08:00 committed by Greg Kroah-Hartman
parent 487709fa1b
commit 8d6da6575f
2 changed files with 41 additions and 1 deletions
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12
Documentation/ABI/testing/sysfs-bus-pci-devices-pvpanic
View File

@ -10,3 +10,15 @@ Description:
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
What: /sys/devices/pci0000:00/*/QEMU0001:00/events
Date: Jan 2021
Contact: zhenwei pi <pizhenwei@bytedance.com>
Description:
RW attribute. Set/get which features in-use. This attribute
is used to enable/disable feature(s) of pvpanic device.
Notice that this value should be a subset of capability.
Format: %x.
Also refer to pvpanic device specification.

30
drivers/misc/pvpanic.c
View File

@ -20,6 +20,7 @@
static void __iomem *base;
static unsigned int capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED;
static unsigned int events;
static ssize_t capability_show(struct device *dev,
struct device_attribute *attr, char *buf)
@ -28,8 +29,34 @@ static ssize_t capability_show(struct device *dev,
}
static DEVICE_ATTR_RO(capability);
static ssize_t events_show(struct device *dev, struct device_attribute *attr, char *buf)
{
return sysfs_emit(buf, "%x", events);
}
static ssize_t events_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
unsigned int tmp;
int err;
err = kstrtouint(buf, 16, &tmp);
if (err)
return err;
if ((tmp & capability) != tmp)
return -EINVAL;
events = tmp;
return count;
}
static DEVICE_ATTR_RW(events);
static struct attribute *pvpanic_dev_attrs[] = {
&dev_attr_capability.attr,
&dev_attr_events.attr,
NULL
};
ATTRIBUTE_GROUPS(pvpanic_dev);
@ -41,7 +68,7 @@ MODULE_LICENSE("GPL");
static void
pvpanic_send_event(unsigned int event)
{
if (event & capability)
if (event & capability & events)
iowrite8(event, base);
}
@ -90,6 +117,7 @@ static int pvpanic_mmio_probe(struct platform_device *pdev)
/* initlize capability by RDPT */
capability &= ioread8(base);
events = capability;
if (capability)
atomic_notifier_chain_register(&panic_notifier_list,