diff mbox series

[v2] xen-pvdevice: Introduce a simplistic xen-pvdevice save state

Message ID 1520982894-4180-1-git-send-email-igor.druzhinin@citrix.com
State New
Headers show
Series [v2] xen-pvdevice: Introduce a simplistic xen-pvdevice save state | expand

Commit Message

Igor Druzhinin March 13, 2018, 11:14 p.m. UTC 
This should help to avoid problems with accessing the device after
migration/resume without PV drivers by migrating its PCI configuration
space state. Without an explicitly defined state record it resets
every time a VM migrates which confuses the OS and makes every
access to xen-pvdevice MMIO region to fail. PV tools enable some
logic to save and restore PCI configuration state from within the VM
every time it migrates which basically hides the issue.

Older systems will acquire the new record when migrated which should
not change their state for worse.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
---
v2: add more concrete info
---
 hw/i386/xen/xen_pvdevice.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Anthony PERARD March 27, 2018, 9:42 a.m. UTC | #1 
On Tue, Mar 13, 2018 at 11:14:54PM +0000, Igor Druzhinin wrote:
> This should help to avoid problems with accessing the device after
> migration/resume without PV drivers by migrating its PCI configuration
> space state. Without an explicitly defined state record it resets
> every time a VM migrates which confuses the OS and makes every
> access to xen-pvdevice MMIO region to fail. PV tools enable some
> logic to save and restore PCI configuration state from within the VM
> every time it migrates which basically hides the issue.
> 
> Older systems will acquire the new record when migrated which should
> not change their state for worse.
> 
> Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
> Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
> ---
> v2: add more concrete info
> ---
>  hw/i386/xen/xen_pvdevice.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)

Acked-by: Anthony PERARD <anthony.perard@citrix.com>

Thanks,
diff mbox series

Patch

diff --git a/hw/i386/xen/xen_pvdevice.c b/hw/i386/xen/xen_pvdevice.c
index f748823..a146f18 100644
--- a/hw/i386/xen/xen_pvdevice.c
+++ b/hw/i386/xen/xen_pvdevice.c
@@ -71,6 +71,16 @@  static const MemoryRegionOps xen_pv_mmio_ops = {
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
+static const VMStateDescription vmstate_xen_pvdevice = {
+    .name = "xen-pvdevice",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_PCI_DEVICE(parent_obj, XenPVDevice),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static void xen_pv_realize(PCIDevice *pci_dev, Error **errp)
 {
     XenPVDevice *d = XEN_PV_DEVICE(pci_dev);
@@ -120,6 +130,7 @@  static void xen_pv_class_init(ObjectClass *klass, void *data)
     k->class_id = PCI_CLASS_SYSTEM_OTHER;
     dc->desc = "Xen PV Device";
     dc->props = xen_pv_props;
+    dc->vmsd = &vmstate_xen_pvdevice;
 }
 
 static const TypeInfo xen_pv_type_info = {