Re: [PATCH v28 03/17] vfio: Add save and load functions for VFIO PCI devices

[Yan Zhao]

On Sat, Oct 24, 2020 at 08:16:30AM -0600, Alex Williamson wrote:
> On Sat, 24 Oct 2020 19:53:39 +0800
> Yan Zhao <yan.y.zhao@intel.com> wrote:
> 
> > hi
> > when I migrating VFs, the PCI_COMMAND is not properly saved. and the
> > target side would meet below bug
> > root@tester:~# [  189.360671] ++++++++++>> reset starts here: 
> > iavf_reset_task !!!
> > [  199.360798] iavf 0000:00:04.0: Reset never finished (0)
> > [  199.380504] kernel BUG at drivers/pci/msi.c:352!
> > [  199.382957] invalid opcode: 0000 [#1] SMP PTI
> > [  199.384855] CPU: 1 PID: 419 Comm: kworker/1:2 Tainted: G           OE    
> >  5.0.0-13-generic #14-Ubuntu
> > [  199.388204] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
> > rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
> > [  199.392401] Workqueue: events iavf_reset_task [iavf]
> > [  199.393586] RIP: 0010:free_msi_irqs+0x17b/0x1b0
> > [  199.394659] Code: 84 e1 fe ff ff 45 31 f6 eb 11 41 83 c6 01 44 39 73 14 
> > 0f 86 ce fe ff ff 8b 7b 10 44 01 f7 e8 3c 7a ba ff 48 83 78 70 00 74 e0 
> > <0f> 0b 49 8d b5 b0 00 00 00 e8 07 27 bb ff e9 cf fe ff ff 48 8b 78
> > [  199.399056] RSP: 0018:ffffabd1006cfdb8 EFLAGS: 00010282
> > [  199.400302] RAX: ffff9e336d8a2800 RBX: ffff9e3333b006c0 RCX: 
> > 0000000000000000
> > [  199.402000] RDX: 0000000000000000 RSI: 0000000000000019 RDI: 
> > ffffffffbaa68100
> > [  199.403168] RBP: ffffabd1006cfde8 R08: ffff9e3375000248 R09: 
> > ffff9e3375000338
> > [  199.404343] R10: 0000000000000000 R11: ffffffffbaa68108 R12: 
> > ffff9e3374ef12c0
> > [  199.405526] R13: ffff9e3374ef1000 R14: 0000000000000000 R15: 
> > ffff9e3371f2d018
> > [  199.406702] FS:  0000000000000000(0000) GS:ffff9e3375b00000(0000) 
> > knlGS:0000000000000000
> > [  199.408027] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [  199.408987] CR2: 00000000ffffffff CR3: 0000000033266000 CR4: 
> > 00000000000006e0
> > [  199.410155] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
> > 0000000000000000
> > [  199.411321] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 
> > 0000000000000400
> > [  199.412437] Call Trace:
> > [  199.412750]  pci_disable_msix+0xf3/0x120
> > [  199.413227]  iavf_reset_interrupt_capability.part.40+0x19/0x40 [iavf]
> > [  199.413998]  iavf_reset_task+0x4b3/0x9d0 [iavf]
> > [  199.414544]  process_one_work+0x20f/0x410
> > [  199.415026]  worker_thread+0x34/0x400
> > [  199.415486]  kthread+0x120/0x140
> > [  199.415876]  ? process_one_work+0x410/0x410
> > [  199.416380]  ? __kthread_parkme+0x70/0x70
> > [  199.416864]  ret_from_fork+0x35/0x40
> > 
> > I fixed it with below patch.
> > 
> > 
> > commit ad3efa0eeea7edb352294bfce35b904b8d3c759c
> > Author: Yan Zhao <yan.y.zhao@intel.com>
> > Date:   Sat Oct 24 19:45:01 2020 +0800
> > 
> >     msix fix.
> >     
> >     Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> > 
> > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> > index f63f15b553..92f71bf933 100644
> > --- a/hw/vfio/pci.c
> > +++ b/hw/vfio/pci.c
> > @@ -2423,8 +2423,14 @@ const VMStateDescription vmstate_vfio_pci_config = {
> >  static void vfio_pci_save_config(VFIODevice *vbasedev, QEMUFile *f)
> >  {
> >      VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
> > +    PCIDevice *pdev = &vdev->pdev;
> > +    uint16_t pci_cmd;
> > +
> > +    pci_cmd = pci_default_read_config(pdev, PCI_COMMAND, 2);
> > +    qemu_put_be16(f, pci_cmd);
> >  
> >      vmstate_save_state(f, &vmstate_vfio_pci_config, vdev, NULL);
> > +
> >  }
> >  
> >  static int vfio_pci_load_config(VFIODevice *vbasedev, QEMUFile *f)
> > @@ -2432,6 +2438,10 @@ static int vfio_pci_load_config(VFIODevice 
> > *vbasedev, QEMUFile *f)
> >      VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
> >      PCIDevice *pdev = &vdev->pdev;
> >      int ret;
> > +    uint16_t pci_cmd;
> > +
> > +    pci_cmd = qemu_get_be16(f);
> > +    vfio_pci_write_config(pdev, PCI_COMMAND, pci_cmd, 2);
> >  
> >      ret = vmstate_load_state(f, &vmstate_vfio_pci_config, vdev, 1);
> >      if (ret) {
> > 
> 
> 
> We need to avoid this sort of ad-hoc stuffing random fields into the
> config stream.  The command register is already migrated in vconfig, it
> only needs to be written through vfio:
> 
> vfio_pci_write_config(pdev, PCI_COMMAND,
>                     pci_get_word(pdev->config, PCI_COMMAND), 2);
> 
yes, it should work. previously we just rely on qemu to save and load
the common fields.

Thanks
Yan

> 
> 
> > On Fri, Oct 23, 2020 at 04:10:29PM +0530, Kirti Wankhede wrote:
> > > Added functions to save and restore PCI device specific data,
> > > specifically config space of PCI device.
> > > 
> > > Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> > > Reviewed-by: Neo Jia <cjia@nvidia.com>
> > > ---
> > >  hw/vfio/pci.c                 | 48 
> > > +++++++++++++++++++++++++++++++++++++++++++
> > >  include/hw/vfio/vfio-common.h |  2 ++
> > >  2 files changed, 50 insertions(+)
> > > 
> > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> > > index bffd5bfe3b78..92cc25a5489f 100644
> > > --- a/hw/vfio/pci.c
> > > +++ b/hw/vfio/pci.c
> > > @@ -41,6 +41,7 @@
> > >  #include "trace.h"
> > >  #include "qapi/error.h"
> > >  #include "migration/blocker.h"
> > > +#include "migration/qemu-file.h"
> > >  
> > >  #define TYPE_VFIO_PCI_NOHOTPLUG "vfio-pci-nohotplug"
> > >  
> > > @@ -2401,11 +2402,58 @@ static Object *vfio_pci_get_object(VFIODevice 
> > > *vbasedev)
> > >      return OBJECT(vdev);
> > >  }
> > >  
> > > +static bool vfio_msix_present(void *opaque, int version_id)
> > > +{
> > > +    PCIDevice *pdev = opaque;
> > > +
> > > +    return msix_present(pdev);
> > > +}
> > > +
> > > +const VMStateDescription vmstate_vfio_pci_config = {
> > > +    .name = "VFIOPCIDevice",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_PCI_DEVICE(pdev, VFIOPCIDevice),
> > > +        VMSTATE_MSIX_TEST(pdev, VFIOPCIDevice, vfio_msix_present),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > > +static void vfio_pci_save_config(VFIODevice *vbasedev, QEMUFile *f)
> > > +{
> > > +    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, 
> > > vbasedev);
> > > +
> > > +    vmstate_save_state(f, &vmstate_vfio_pci_config, vdev, NULL);
> > > +}
> > > +
> > > +static int vfio_pci_load_config(VFIODevice *vbasedev, QEMUFile *f)
> > > +{
> > > +    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, 
> > > vbasedev);
> > > +    PCIDevice *pdev = &vdev->pdev;
> > > +    int ret;
> > > +
> > > +    ret = vmstate_load_state(f, &vmstate_vfio_pci_config, vdev, 1);
> > > +    if (ret) {
> > > +        return ret;
> > > +    }
> > > +
> > > +    if (msi_enabled(pdev)) {
> > > +        vfio_msi_enable(vdev);
> > > +    } else if (msix_enabled(pdev)) {
> > > +        vfio_msix_enable(vdev);
> > > +    }
> > > +
> > > +    return ret;
> > > +}
> > > +
> > >  static VFIODeviceOps vfio_pci_ops = {
> > >      .vfio_compute_needs_reset = vfio_pci_compute_needs_reset,
> > >      .vfio_hot_reset_multi = vfio_pci_hot_reset_multi,
> > >      .vfio_eoi = vfio_intx_eoi,
> > >      .vfio_get_object = vfio_pci_get_object,
> > > +    .vfio_save_config = vfio_pci_save_config,
> > > +    .vfio_load_config = vfio_pci_load_config,
> > >  };
> > >  
> > >  int vfio_populate_vga(VFIOPCIDevice *vdev, Error **errp)
> > > diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> > > index fe99c36a693a..ba6169cd926e 100644
> > > --- a/include/hw/vfio/vfio-common.h
> > > +++ b/include/hw/vfio/vfio-common.h
> > > @@ -120,6 +120,8 @@ struct VFIODeviceOps {
> > >      int (*vfio_hot_reset_multi)(VFIODevice *vdev);
> > >      void (*vfio_eoi)(VFIODevice *vdev);
> > >      Object *(*vfio_get_object)(VFIODevice *vdev);
> > > +    void (*vfio_save_config)(VFIODevice *vdev, QEMUFile *f);
> > > +    int (*vfio_load_config)(VFIODevice *vdev, QEMUFile *f);
> > >  };
> > >  
> > >  typedef struct VFIOGroup {
> > > -- 
> > > 2.7.0
> > >   
> > 
>