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

From: Alex Williamson
Subject: Re: [PATCH v28 03/17] vfio: Add save and load functions for VFIO PCI devices
Date: Sat, 24 Oct 2020 14:23:48 -0600 
On Sun, 25 Oct 2020 01:18:37 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> On 10/24/2020 7:46 PM, 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 verified MSIx with SRIOV VF, and I don't see this issue at my end.
> 
> >> 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);
> >   
> 
> I verified at my end again.
> pci command value (using pci_default_read_config()) before 
> vmstate_save_state() is 0x507 and at destination after 
> vmstate_load_state() is also 0x507 - with pci_default_read_config() and 
> the cached config space value using pci_get_word() - both are 0x507.
> VM restores successfully.
> 
> Yan, can you share pci command values before and after as above? what 
> exactly is missing?

pci_default_read_config() or pci_get_word() only read from virtual
config space, something needs to write it through to the device on the
target, much like we're doing to enable msi and msix.  Thanks,

Alex


> >> 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
> >>>      
> >>  
> >   
>
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