From: Cornelia Huck <cohuck@redhat.com>
To: Kirti Wankhede <kwankhede@nvidia.com>
Cc: cjia@nvidia.com, aik@ozlabs.ru, Zhengxiao.zx@alibaba-inc.com,
shuangtai.tst@alibaba-inc.com, qemu-devel@nongnu.org,
peterx@redhat.com, eauger@redhat.com, yi.l.liu@intel.com,
quintela@redhat.com, ziye.yang@intel.com, armbru@redhat.com,
mlevitsk@redhat.com, pasic@linux.ibm.com, felipe@nutanix.com,
zhi.a.wang@intel.com, kevin.tian@intel.com, yan.y.zhao@intel.com,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
alex.williamson@redhat.com, changpeng.liu@intel.com,
eskultet@redhat.com, Ken.Xue@amd.com,
jonathan.davies@nutanix.com, pbonzini@redhat.com
Subject: Re: [PATCH v26 05/17] vfio: Add VM state change handler to know state of VM
Date: Tue, 20 Oct 2020 12:51:05 +0200 [thread overview]
Message-ID: <20201020125105.5cd790df.cohuck@redhat.com> (raw)
In-Reply-To: <3dd3fe95-c81a-de40-47b0-24f0772974d4@nvidia.com>
On Sun, 18 Oct 2020 01:54:56 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:
> On 9/29/2020 4:33 PM, Dr. David Alan Gilbert wrote:
> > * Cornelia Huck (cohuck@redhat.com) wrote:
> >> On Wed, 23 Sep 2020 04:54:07 +0530
> >> Kirti Wankhede <kwankhede@nvidia.com> wrote:
> >>
> >>> VM state change handler gets called on change in VM's state. This is used to set
> >>> VFIO device state to _RUNNING.
> >>>
> >>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> >>> Reviewed-by: Neo Jia <cjia@nvidia.com>
> >>> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> >>> ---
> >>> hw/vfio/migration.c | 136 ++++++++++++++++++++++++++++++++++++++++++
> >>> hw/vfio/trace-events | 3 +-
> >>> include/hw/vfio/vfio-common.h | 4 ++
> >>> 3 files changed, 142 insertions(+), 1 deletion(-)
> >>>
> >>
> >> (...)
> >>
> >>> +static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask,
> >>> + uint32_t value)
> >>
> >> I think I've mentioned that before, but this function could really
> >> benefit from a comment what mask and value mean.
> >>
>
> Adding a comment as:
>
> /*
> * Write device_state field to inform the vendor driver about the
> device state
> * to be transitioned to.
> * vbasedev: VFIO device
> * mask : bits set in the mask are preserved in device_state
> * value: bits set in the value are set in device_state
> * Remaining bits in device_state are cleared.
> */
Maybe:
"Change the device_state register for device @vbasedev. Bits set in
@mask are preserved, bits set in @value are set, and bits not set in
either @mask or @value are cleared in device_state. If the register
cannot be accessed, the resulting state would be invalid, or the device
enters an error state, an error is returned." ?
>
>
> >>> +{
> >>> + VFIOMigration *migration = vbasedev->migration;
> >>> + VFIORegion *region = &migration->region;
> >>> + off_t dev_state_off = region->fd_offset +
> >>> + offsetof(struct vfio_device_migration_info, device_state);
> >>> + uint32_t device_state;
> >>> + int ret;
> >>> +
> >>> + ret = vfio_mig_read(vbasedev, &device_state, sizeof(device_state),
> >>> + dev_state_off);
> >>> + if (ret < 0) {
> >>> + return ret;
> >>> + }
> >>> +
> >>> + device_state = (device_state & mask) | value;
> >>> +
> >>> + if (!VFIO_DEVICE_STATE_VALID(device_state)) {
> >>> + return -EINVAL;
> >>> + }
> >>> +
> >>> + ret = vfio_mig_write(vbasedev, &device_state, sizeof(device_state),
> >>> + dev_state_off);
> >>> + if (ret < 0) {
> >>> + ret = vfio_mig_read(vbasedev, &device_state, sizeof(device_state),
> >>> + dev_state_off);
> >>> + if (ret < 0) {
> >>> + return ret;
> >>> + }
> >>> +
> >>> + if (VFIO_DEVICE_STATE_IS_ERROR(device_state)) {
> >>> + hw_error("%s: Device is in error state 0x%x",
> >>> + vbasedev->name, device_state);
> >>> + return -EFAULT;
> >>
> >> Is -EFAULT a good return value here? Maybe -EIO?
> >>
>
> Ok. Changing to -EIO.
>
> >>> + }
> >>> + }
> >>> +
> >>> + vbasedev->device_state = device_state;
> >>> + trace_vfio_migration_set_state(vbasedev->name, device_state);
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void vfio_vmstate_change(void *opaque, int running, RunState state)
> >>> +{
> >>> + VFIODevice *vbasedev = opaque;
> >>> +
> >>> + if ((vbasedev->vm_running != running)) {
> >>> + int ret;
> >>> + uint32_t value = 0, mask = 0;
> >>> +
> >>> + if (running) {
> >>> + value = VFIO_DEVICE_STATE_RUNNING;
> >>> + if (vbasedev->device_state & VFIO_DEVICE_STATE_RESUMING) {
> >>> + mask = ~VFIO_DEVICE_STATE_RESUMING;
> >>
> >> I've been staring at this for some time and I think that the desired
> >> result is
> >> - set _RUNNING
> >> - if _RESUMING was set, clear it, but leave the other bits intact
>
> Upto here, you're correct.
>
> >> - if _RESUMING was not set, clear everything previously set
> >> This would really benefit from a comment (or am I the only one
> >> struggling here?)
> >>
>
> Here mask should be ~0. Correcting it.
Hm, now I'm confused. With value == _RUNNING, ~_RUNNING and ~0 as mask
should be equivalent, shouldn't they?
>
>
> >>> + }
> >>> + } else {
> >>> + mask = ~VFIO_DEVICE_STATE_RUNNING;
> >>> + }
> >>> +
> >>> + ret = vfio_migration_set_state(vbasedev, mask, value);
> >>> + if (ret) {
> >>> + /*
> >>> + * vm_state_notify() doesn't support reporting failure. If such
> >>> + * error reporting support added in furure, migration should be
> >>> + * aborted.
> >>
> >>
> >> "We should abort the migration in this case, but vm_state_notify()
> >> currently does not support reporting failures."
> >>
> >> ?
> >>
>
> Ok. Updating comment as suggested here.
>
> >> Can/should we mark the failing device in some way?
> >
> > I think you can call qemu_file_set_error on the migration stream to
> > force an error.
> >
>
> It should be as below, right?
> qemu_file_set_error(migrate_get_current()->to_dst_file, ret);
Does this indicate in any way which device was causing problems? (I'm
not sure how visible the error_report would be?)
>
>
> Thanks,
> Kirti
>
> > Dave
> >
> >>> + */
> >>> + error_report("%s: Failed to set device state 0x%x",
> >>> + vbasedev->name, value & mask);
> >>> + }
> >>> + vbasedev->vm_running = running;
> >>> + trace_vfio_vmstate_change(vbasedev->name, running, RunState_str(state),
> >>> + value & mask);
> >>> + }
> >>> +}
> >>> +
> >>> static int vfio_migration_init(VFIODevice *vbasedev,
> >>> struct vfio_region_info *info)
> >>> {
> >>
> >> (...)
>
next prev parent reply other threads:[~2020-10-20 10:52 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 23:24 [PATCH QEMU v25 00/17] Add migration support for VFIO devices Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 01/17] vfio: Add function to unmap VFIO region Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 02/17] vfio: Add vfio_get_object callback to VFIODeviceOps Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 03/17] vfio: Add save and load functions for VFIO PCI devices Kirti Wankhede
2020-09-23 6:38 ` Zenghui Yu
2020-09-24 22:49 ` Alex Williamson
2020-10-21 9:30 ` Zenghui Yu
2020-10-21 19:03 ` Alex Williamson
2020-09-22 23:24 ` [PATCH v26 04/17] vfio: Add migration region initialization and finalize function Kirti Wankhede
2020-09-24 14:08 ` Cornelia Huck
2020-10-17 20:14 ` Kirti Wankhede
2020-09-25 20:20 ` Alex Williamson
2020-09-28 9:39 ` Cornelia Huck
2020-10-17 20:17 ` Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 05/17] vfio: Add VM state change handler to know state of VM Kirti Wankhede
2020-09-24 15:02 ` Cornelia Huck
2020-09-29 11:03 ` Dr. David Alan Gilbert
2020-10-17 20:24 ` Kirti Wankhede
2020-10-20 10:51 ` Cornelia Huck [this message]
2020-10-21 5:33 ` Kirti Wankhede
2020-10-22 7:51 ` Cornelia Huck
2020-10-22 15:42 ` Kirti Wankhede
2020-10-22 15:49 ` Cornelia Huck
2020-09-25 20:20 ` Alex Williamson
2020-10-17 20:30 ` Kirti Wankhede
2020-10-17 23:44 ` Alex Williamson
2020-10-18 17:43 ` Kirti Wankhede
2020-10-19 17:51 ` Alex Williamson
2020-10-20 10:23 ` Cornelia Huck
2020-09-22 23:24 ` [PATCH v26 06/17] vfio: Add migration state change notifier Kirti Wankhede
2020-09-25 20:20 ` Alex Williamson
2020-10-17 20:35 ` Kirti Wankhede
2020-10-19 17:57 ` Alex Williamson
2020-10-20 10:55 ` Cornelia Huck
2020-09-22 23:24 ` [PATCH v26 07/17] vfio: Register SaveVMHandlers for VFIO device Kirti Wankhede
2020-09-24 15:15 ` Philippe Mathieu-Daudé
2020-09-29 10:19 ` Dr. David Alan Gilbert
2020-10-17 20:36 ` Kirti Wankhede
2020-09-25 11:53 ` Cornelia Huck
2020-10-18 20:55 ` Kirti Wankhede
2020-10-20 15:51 ` Cornelia Huck
2020-09-25 20:20 ` Alex Williamson
2020-10-18 17:40 ` Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 08/17] vfio: Add save state functions to SaveVMHandlers Kirti Wankhede
2020-09-23 11:42 ` Wang, Zhi A
2020-10-21 14:30 ` Kirti Wankhede
2020-09-25 21:02 ` Alex Williamson
2020-10-18 18:00 ` Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 09/17] vfio: Add load " Kirti Wankhede
2020-10-01 10:07 ` Cornelia Huck
2020-10-18 20:47 ` Kirti Wankhede
2020-10-20 16:25 ` Cornelia Huck
2020-09-22 23:24 ` [PATCH v26 10/17] memory: Set DIRTY_MEMORY_MIGRATION when IOMMU is enabled Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 11/17] vfio: Get migration capability flags for container Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 12/17] vfio: Add function to start and stop dirty pages tracking Kirti Wankhede
2020-09-25 21:55 ` Alex Williamson
2020-10-18 20:52 ` Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 13/17] vfio: create mapped iova list when vIOMMU is enabled Kirti Wankhede
2020-09-25 22:23 ` Alex Williamson
2020-10-19 6:01 ` Kirti Wankhede
2020-10-19 17:24 ` Alex Williamson
2020-10-19 19:15 ` Kirti Wankhede
2020-10-19 20:07 ` Alex Williamson
2020-09-22 23:24 ` [PATCH v26 14/17] vfio: Add vfio_listener_log_sync to mark dirty pages Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 15/17] vfio: Add ioctl to get dirty pages bitmap during dma unmap Kirti Wankhede
2020-09-22 23:24 ` [PATCH v26 16/17] vfio: Make vfio-pci device migration capable Kirti Wankhede
2020-09-25 12:17 ` Cornelia Huck
2020-09-22 23:24 ` [PATCH v26 17/17] qapi: Add VFIO devices migration stats in Migration stats Kirti Wankhede
2020-09-24 15:14 ` Eric Blake
2020-09-25 22:55 ` Alex Williamson
2020-09-29 10:40 ` Dr. David Alan Gilbert
2020-09-23 7:06 ` [PATCH QEMU v25 00/17] Add migration support for VFIO devices Zenghui Yu
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