xen/pci: Add a function to reset device for xen

When device on dom0 side has been reset, the vpci on Xen side
won't get notification, so that the cached state in vpci is
all out of date with the real device state.
To solve that problem, add a new function to clear all vpci
device state when device is reset on dom0 side.

And call that function in pcistub_init_device. Because when
using "pci-assignable-add" to assign a passthrough device in
Xen, it will reset passthrough device and the vpci state will
out of date, and then device will fail to restore bar state.

Signed-off-by: Jiqian Chen <Jiqian.Chen@amd.com>
Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Jiqian Chen <Jiqian.Chen@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Message-ID: <20240924061437.2636766-2-Jiqian.Chen@amd.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

drivers/xen/pci.c

@@ -173,6 +173,19 @@ static int xen_remove_device(struct device *dev)
 	return r;
 }
 
+int xen_reset_device(const struct pci_dev *dev)
+{
+	struct pci_device_reset device = {
+		.dev.seg = pci_domain_nr(dev->bus),
+		.dev.bus = dev->bus->number,
+		.dev.devfn = dev->devfn,
+		.flags = PCI_DEVICE_RESET_FLR,
+	};
+
+	return HYPERVISOR_physdev_op(PHYSDEVOP_pci_device_reset, &device);
+}
+EXPORT_SYMBOL_GPL(xen_reset_device);
+
 static int xen_pci_notifier(struct notifier_block *nb,
 			    unsigned long action, void *data)
 {

drivers/xen/xen-pciback/pci_stub.c

@@ -89,6 +89,16 @@ static struct pcistub_device *pcistub_device_alloc(struct pci_dev *dev)
 	return psdev;
 }
 
+static int pcistub_reset_device_state(struct pci_dev *dev)
+{
+	__pci_reset_function_locked(dev);
+
+	if (!xen_pv_domain())
+		return xen_reset_device(dev);
+	else
+		return 0;
+}
+
 /* Don't call this directly as it's called by pcistub_device_put */
 static void pcistub_device_release(struct kref *kref)
 {
@@ -107,7 +117,7 @@ static void pcistub_device_release(struct kref *kref)
 	/* Call the reset function which does not take lock as this
 	 * is called from "unbind" which takes a device_lock mutex.
 	 */
-	__pci_reset_function_locked(dev);
+	pcistub_reset_device_state(dev);
 	if (dev_data &&
 	    pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state))
 		dev_info(&dev->dev, "Could not reload PCI state\n");
@@ -284,7 +294,7 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
 	 * (so it's ready for the next domain)
 	 */
 	device_lock_assert(&dev->dev);
-	__pci_reset_function_locked(dev);
+	pcistub_reset_device_state(dev);
 
 	dev_data = pci_get_drvdata(dev);
 	ret = pci_load_saved_state(dev, dev_data->pci_saved_state);
@@ -420,7 +430,9 @@ static int pcistub_init_device(struct pci_dev *dev)
 		dev_err(&dev->dev, "Could not store PCI conf saved state!\n");
 	else {
 		dev_dbg(&dev->dev, "resetting (FLR, D3, etc) the device\n");
-		__pci_reset_function_locked(dev);
+		err = pcistub_reset_device_state(dev);
+		if (err)
+			goto config_release;
 		pci_restore_state(dev);
 	}
 	/* Now disable the device (this also ensures some private device

include/xen/interface/physdev.h

@@ -256,6 +256,13 @@ struct physdev_pci_device_add {
  */
 #define PHYSDEVOP_prepare_msix          30
 #define PHYSDEVOP_release_msix          31
+/*
+ * Notify the hypervisor that a PCI device has been reset, so that any
+ * internally cached state is regenerated.  Should be called after any
+ * device reset performed by the hardware domain.
+ */
+#define PHYSDEVOP_pci_device_reset      32
+
 struct physdev_pci_device {
     /* IN */
     uint16_t seg;
@@ -263,6 +270,16 @@ struct physdev_pci_device {
     uint8_t devfn;
 };
 
+struct pci_device_reset {
+    struct physdev_pci_device dev;
+#define PCI_DEVICE_RESET_COLD 0x0
+#define PCI_DEVICE_RESET_WARM 0x1
+#define PCI_DEVICE_RESET_HOT  0x2
+#define PCI_DEVICE_RESET_FLR  0x3
+#define PCI_DEVICE_RESET_MASK 0x3
+    uint32_t flags;
+};
+
 #define PHYSDEVOP_DBGP_RESET_PREPARE    1
 #define PHYSDEVOP_DBGP_RESET_DONE       2
 

include/xen/pci.h

@@ -4,10 +4,16 @@
 #define __XEN_PCI_H__
 
 #if defined(CONFIG_XEN_DOM0)
+int xen_reset_device(const struct pci_dev *dev);
 int xen_find_device_domain_owner(struct pci_dev *dev);
 int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
 int xen_unregister_device_domain_owner(struct pci_dev *dev);
 #else
+static inline int xen_reset_device(const struct pci_dev *dev)
+{
+	return -1;
+}
+
 static inline int xen_find_device_domain_owner(struct pci_dev *dev)
 {
 	return -1;