misc/pvpanic: add PCI driver

Add support for pvpanic PCI device added in qemu [1]. At probe time, obtain the
address where to read/write pvpanic events and pass it to the generic handling
code. Will follow the same logic as pvpanic MMIO device driver. At remove time,
unmap base address and disable PCI device.

[1] https://github.com/qemu/qemu/commit/9df52f58e76e904fb141b10318362d718f470db2Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Link: https://lore.kernel.org/r/1616597356-20696-4-git-send-email-mihai.carabas@oracle.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

-What:		/sys/devices/pci0000:00/*/QEMU0001:00/capability
+What:		/sys/devices/pci0000:00/*/QEMU0001:00/capability for MMIO
+		/sys/bus/pci/drivers/pvpanic-pci/0000:00:0*.0/capability for PCI
 Date:		Jan 2021
 Contact:	zhenwei pi <pizhenwei@bytedance.com>
 Description:
@@ -12,6 +13,7 @@ Description:
 		https://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/specs/pvpanic.txt
 
 What:		/sys/devices/pci0000:00/*/QEMU0001:00/events
+		/sys/bus/pci/drivers/pvpanic-pci/0000:00:0*.0/events for PCI
 Date:		Jan 2021
 Contact:	zhenwei pi <pizhenwei@bytedance.com>
 Description:

drivers/misc/pvpanic/Kconfig

@@ -17,3 +17,11 @@ config PVPANIC_MMIO
 	depends on HAS_IOMEM && (ACPI || OF) && PVPANIC
 	help
 	  This driver provides support for the MMIO pvpanic device.
+
+config PVPANIC_PCI
+	tristate "pvpanic PCI device support"
+	depends on PCI && PVPANIC
+	help
+	  This driver provides support for the PCI pvpanic device.
+	  pvpanic is a paravirtualized device provided by QEMU which
+	  forwards the panic events from the guest to the host.

drivers/misc/pvpanic/Makefile

@@ -5,3 +5,4 @@
 # Copyright (C) 2021 Oracle.
 #
 obj-$(CONFIG_PVPANIC_MMIO)	+= pvpanic.o pvpanic-mmio.o
+obj-$(CONFIG_PVPANIC_PCI)	+= pvpanic.o pvpanic-pci.o

drivers/misc/pvpanic/pvpanic-pci.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Pvpanic PCI Device Support
+ *
+ *  Copyright (C) 2021 Oracle.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+
+#include <uapi/misc/pvpanic.h>
+
+#include "pvpanic.h"
+
+#define PCI_VENDOR_ID_REDHAT             0x1b36
+#define PCI_DEVICE_ID_REDHAT_PVPANIC     0x0011
+
+MODULE_AUTHOR("Mihai Carabas <mihai.carabas@oracle.com>");
+MODULE_DESCRIPTION("pvpanic device driver ");
+MODULE_LICENSE("GPL");
+
+static const struct pci_device_id pvpanic_pci_id_tbl[]  = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_REDHAT, PCI_DEVICE_ID_REDHAT_PVPANIC)},
+	{}
+};
+
+static ssize_t capability_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct pvpanic_instance *pi = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%x\n", pi->capability);
+}
+static DEVICE_ATTR_RO(capability);
+
+static ssize_t events_show(struct device *dev,  struct device_attribute *attr, char *buf)
+{
+	struct pvpanic_instance *pi = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%x\n", pi->events);
+}
+
+static ssize_t events_store(struct device *dev,  struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct pvpanic_instance *pi = dev_get_drvdata(dev);
+	unsigned int tmp;
+	int err;
+
+	err = kstrtouint(buf, 16, &tmp);
+	if (err)
+		return err;
+
+	if ((tmp & pi->capability) != tmp)
+		return -EINVAL;
+
+	pi->events = tmp;
+
+	return count;
+}
+static DEVICE_ATTR_RW(events);
+
+static struct attribute *pvpanic_pci_dev_attrs[] = {
+	&dev_attr_capability.attr,
+	&dev_attr_events.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(pvpanic_pci_dev);
+
+static int pvpanic_pci_probe(struct pci_dev *pdev,
+			     const struct pci_device_id *ent)
+{
+	struct device *dev = &pdev->dev;
+	struct pvpanic_instance *pi;
+	void __iomem *base;
+	int ret;
+
+	ret = pci_enable_device(pdev);
+	if (ret < 0)
+		return ret;
+
+	base = pci_iomap(pdev, 0, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	pi = kmalloc(sizeof(*pi), GFP_ATOMIC);
+	if (!pi)
+		return -ENOMEM;
+
+	pi->base = base;
+	pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED;
+
+	/* initlize capability by RDPT */
+	pi->capability &= ioread8(base);
+	pi->events = pi->capability;
+
+	dev_set_drvdata(dev, pi);
+
+	return pvpanic_probe(pi);
+}
+
+static void pvpanic_pci_remove(struct pci_dev *pdev)
+{
+	struct pvpanic_instance *pi = dev_get_drvdata(&pdev->dev);
+
+	pvpanic_remove(pi);
+	iounmap(pi->base);
+	kfree(pi);
+	pci_disable_device(pdev);
+}
+
+static struct pci_driver pvpanic_pci_driver = {
+	.name =         "pvpanic-pci",
+	.id_table =     pvpanic_pci_id_tbl,
+	.probe =        pvpanic_pci_probe,
+	.remove =       pvpanic_pci_remove,
+	.driver = {
+		.dev_groups = pvpanic_pci_dev_groups,
+	},
+};
+
+module_pci_driver(pvpanic_pci_driver);