[Qemu-devel] [PATCH] device-assignment: register a reset function

[Qemu-devel] [PATCH] device-assignment: register a reset function

[Bernhard Kohl]

This is necessary because during reboot of a VM the assigned devices
continue DMA transfers which causes memory corruption.

Signed-off-by: Thomas Ostler <thomas.ostler@nsn.com>
Signed-off-by: Bernhard Kohl <bernhard.kohl@nsn.com>
---
Sorry for for the long delay. Finally we added Alex' suggestions
and rebased the patch.

Thanks
Bernhard
---
 hw/device-assignment.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/hw/device-assignment.c b/hw/device-assignment.c
index 5f5bde1..3f8de66 100644
--- a/hw/device-assignment.c
+++ b/hw/device-assignment.c
@@ -1434,6 +1434,17 @@ static void assigned_dev_unregister_msix_mmio(AssignedDevice *dev)
     dev->msix_table_page = NULL;
 }
 
+static void reset_assigned_device(DeviceState *dev)
+{
+    PCIDevice *d = DO_UPCAST(PCIDevice, qdev, dev);
+    uint32_t conf;
+
+    /* reset the bus master bit to avoid further DMA transfers */
+    conf = assigned_dev_pci_read_config(d, PCI_COMMAND, 2);
+    conf &= ~PCI_COMMAND_MASTER;
+    assigned_dev_pci_write_config(d, PCI_COMMAND, conf, 2);
+}
+
 static int assigned_initfn(struct PCIDevice *pci_dev)
 {
     AssignedDevice *dev = DO_UPCAST(AssignedDevice, dev, pci_dev);
@@ -1544,6 +1555,7 @@ static PCIDeviceInfo assign_info = {
     .qdev.name    = "pci-assign",
     .qdev.desc    = "pass through host pci devices to the guest",
     .qdev.size    = sizeof(AssignedDevice),
+    .qdev.reset   = reset_assigned_device,
     .init         = assigned_initfn,
     .exit         = assigned_exitfn,
     .config_read  = assigned_dev_pci_read_config,
-- 
1.7.2.3

[Qemu-devel] Re: [PATCH] device-assignment: register a reset function

[Jan Kiszka]

[Wrong list, it's not upstream yet. I'm migrating the thread to kvm.]

Am 15.11.2010 12:33, Bernhard Kohl wrote:
> This is necessary because during reboot of a VM the assigned devices
> continue DMA transfers which causes memory corruption.
> 
> Signed-off-by: Thomas Ostler <thomas.ostler@nsn.com>
> Signed-off-by: Bernhard Kohl <bernhard.kohl@nsn.com>
> ---
> Sorry for for the long delay. Finally we added Alex' suggestions
> and rebased the patch.
> 
> Thanks
> Bernhard
> ---
>  hw/device-assignment.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index 5f5bde1..3f8de66 100644
> --- a/hw/device-assignment.c
> +++ b/hw/device-assignment.c
> @@ -1434,6 +1434,17 @@ static void assigned_dev_unregister_msix_mmio(AssignedDevice *dev)
>      dev->msix_table_page = NULL;
>  }
>  
> +static void reset_assigned_device(DeviceState *dev)
> +{
> +    PCIDevice *d = DO_UPCAST(PCIDevice, qdev, dev);
> +    uint32_t conf;
> +
> +    /* reset the bus master bit to avoid further DMA transfers */
> +    conf = assigned_dev_pci_read_config(d, PCI_COMMAND, 2);
> +    conf &= ~PCI_COMMAND_MASTER;
> +    assigned_dev_pci_write_config(d, PCI_COMMAND, conf, 2);

What about writing to /sys/bus/pci/devices/$DEVICE/reset? You probably
still need to put the command word into the reset state (ie. no RMW in
any case, just write 0), but the hardware should receive a reset as well
- if it is capable of doing a function-level reset, but we should at
least try.

> +}
> +
>  static int assigned_initfn(struct PCIDevice *pci_dev)
>  {
>      AssignedDevice *dev = DO_UPCAST(AssignedDevice, dev, pci_dev);
> @@ -1544,6 +1555,7 @@ static PCIDeviceInfo assign_info = {
>      .qdev.name    = "pci-assign",
>      .qdev.desc    = "pass through host pci devices to the guest",
>      .qdev.size    = sizeof(AssignedDevice),
> +    .qdev.reset   = reset_assigned_device,
>      .init         = assigned_initfn,
>      .exit         = assigned_exitfn,
>      .config_read  = assigned_dev_pci_read_config,

Jan

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