[RFC XEN PATCH v3 1/3] xen/vpci: Clear all vpci status of device

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

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all out of date compare with the real device state.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

Co-developed-by: Huang Rui <ray.huang@xxxxxxx>
Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
 xen/arch/x86/hvm/hypercall.c |  1 +
 xen/drivers/pci/physdev.c    | 35 +++++++++++++++++++++++++++++++++++
 xen/drivers/vpci/vpci.c      |  9 +++++++++
 xen/include/public/physdev.h |  8 ++++++++
 xen/include/xen/vpci.h       |  6 ++++++
 5 files changed, 59 insertions(+)

diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
index eeb73e1aa5..6ad5b4d5f1 100644
--- a/xen/arch/x86/hvm/hypercall.c
+++ b/xen/arch/x86/hvm/hypercall.c
@@ -84,6 +84,7 @@ long hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
     case PHYSDEVOP_pci_mmcfg_reserved:
     case PHYSDEVOP_pci_device_add:
     case PHYSDEVOP_pci_device_remove:
+    case PHYSDEVOP_pci_device_state_reset:
     case PHYSDEVOP_dbgp_op:
         if ( !is_hardware_domain(currd) )
             return -ENOSYS;
diff --git a/xen/drivers/pci/physdev.c b/xen/drivers/pci/physdev.c
index 42db3e6d13..6ee2edb86a 100644
--- a/xen/drivers/pci/physdev.c
+++ b/xen/drivers/pci/physdev.c
@@ -2,6 +2,7 @@
 #include <xen/guest_access.h>
 #include <xen/hypercall.h>
 #include <xen/init.h>
+#include <xen/vpci.h>
 
 #ifndef COMPAT
 typedef long ret_t;
@@ -67,6 +68,40 @@ ret_t pci_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) 
arg)
         break;
     }
 
+    case PHYSDEVOP_pci_device_state_reset: {
+        struct physdev_pci_device dev;
+        struct pci_dev *pdev;
+
+        if ( !is_pci_passthrough_enabled() )
+            return -EOPNOTSUPP;
+
+        ret = -EFAULT;
+        if ( copy_from_guest(&dev, arg, 1) != 0 )
+            break;
+
+        ret = xsm_resource_setup_pci(XSM_PRIV,
+                                     (dev.seg << 16) | (dev.bus << 8) |
+                                     dev.devfn);
+        if ( ret )
+            break;
+
+        pcidevs_lock();
+        pdev = pci_get_pdev(NULL, PCI_SBDF(dev.seg, dev.bus, dev.devfn));
+        if ( !pdev )
+        {
+            ret = -ENODEV;
+            pcidevs_unlock();
+            break;
+        }
+
+        ret = vpci_reset_device_state(pdev);
+        if ( ret )
+            printk(XENLOG_ERR "PCI reset device %pp state failed\n",
+                   &pdev->sbdf);
+        pcidevs_unlock();
+        break;
+    }
+
     default:
         ret = -ENOSYS;
         break;
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index 72ef277c4f..3c64cb10cc 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -107,6 +107,15 @@ int vpci_add_handlers(struct pci_dev *pdev)
 
     return rc;
 }
+
+int vpci_reset_device_state(struct pci_dev *pdev)
+{
+    ASSERT(pcidevs_locked());
+
+    vpci_remove_device(pdev);
+    return vpci_add_handlers(pdev);
+}
+
 #endif /* __XEN__ */
 
 static int vpci_register_cmp(const struct vpci_register *r1,
diff --git a/xen/include/public/physdev.h b/xen/include/public/physdev.h
index f0c0d4727c..92c2f28bca 100644
--- a/xen/include/public/physdev.h
+++ b/xen/include/public/physdev.h
@@ -296,6 +296,14 @@ DEFINE_XEN_GUEST_HANDLE(physdev_pci_device_add_t);
  */
 #define PHYSDEVOP_prepare_msix          30
 #define PHYSDEVOP_release_msix          31
+/*
+ * On PVH dom0, when device is 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. Use this to reset
+ * the vpci state of device.
+ */
+#define PHYSDEVOP_pci_device_state_reset     32
+
 struct physdev_pci_device {
     /* IN */
     uint16_t seg;
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
index d20c301a3d..d6377424f0 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -30,6 +30,7 @@ int __must_check vpci_add_handlers(struct pci_dev *pdev);
 
 /* Remove all handlers and free vpci related structures. */
 void vpci_remove_device(struct pci_dev *pdev);
+int vpci_reset_device_state(struct pci_dev *pdev);
 
 /* Add/remove a register handler. */
 int __must_check vpci_add_register_mask(struct vpci *vpci,
@@ -262,6 +263,11 @@ static inline int vpci_add_handlers(struct pci_dev *pdev)
 
 static inline void vpci_remove_device(struct pci_dev *pdev) { }
 
+static inline int vpci_reset_device_state(struct pci_dev *pdev)
+{
+    return 0;
+}
+
 static inline void vpci_dump_msi(void) { }
 
 static inline uint32_t vpci_read(pci_sbdf_t sbdf, unsigned int reg,
-- 
2.34.1