From: Kirti Wankhede <kwankhede@nvidia.com>
To: Yan Zhao <yan.y.zhao@intel.com>
Cc: "Zhengxiao.zx@Alibaba-inc.com" <Zhengxiao.zx@Alibaba-inc.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"cjia@nvidia.com" <cjia@nvidia.com>,
"eskultet@redhat.com" <eskultet@redhat.com>,
"Yang, Ziye" <ziye.yang@intel.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"cohuck@redhat.com" <cohuck@redhat.com>,
"shuangtai.tst@alibaba-inc.com" <shuangtai.tst@alibaba-inc.com>,
"dgilbert@redhat.com" <dgilbert@redhat.com>,
"Wang, Zhi A" <zhi.a.wang@intel.com>,
"mlevitsk@redhat.com" <mlevitsk@redhat.com>,
"pasic@linux.ibm.com" <pasic@linux.ibm.com>,
"aik@ozlabs.ru" <aik@ozlabs.ru>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"eauger@redhat.com" <eauger@redhat.com>,
"felipe@nutanix.com" <felipe@nutanix.com>,
"jonathan.davies@nutanix.com" <jonathan.davies@nutanix.com>,
"Liu, Changpeng" <changpeng.liu@intel.com>,
"Ken.Xue@amd.com" <Ken.Xue@amd.com>
Subject: Re: [PATCH v16 QEMU 09/16] vfio: Add save state functions to SaveVMHandlers
Date: Mon, 11 May 2020 15:52:47 +0530 [thread overview]
Message-ID: <7653e660-1360-7c2b-c4c7-3b53081f14e3@nvidia.com> (raw)
In-Reply-To: <20200509053131.GC26056@joy-OptiPlex-7040>
On 5/9/2020 11:01 AM, Yan Zhao wrote:
> On Wed, Mar 25, 2020 at 05:09:07AM +0800, Kirti Wankhede wrote:
>> Added .save_live_pending, .save_live_iterate and .save_live_complete_precopy
>> functions. These functions handles pre-copy and stop-and-copy phase.
>>
>> In _SAVING|_RUNNING device state or pre-copy phase:
>> - read pending_bytes. If pending_bytes > 0, go through below steps.
>> - read data_offset - indicates kernel driver to write data to staging
>> buffer.
>> - read data_size - amount of data in bytes written by vendor driver in
>> migration region.
> I think we should change the sequence of reading data_size and
> data_offset. see the next comment below.
>
>> - read data_size bytes of data from data_offset in the migration region.
>> - Write data packet to file stream as below:
>> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data,
>> VFIO_MIG_FLAG_END_OF_STATE }
>>
>> In _SAVING device state or stop-and-copy phase
>> a. read config space of device and save to migration file stream. This
>> doesn't need to be from vendor driver. Any other special config state
>> from driver can be saved as data in following iteration.
>> b. read pending_bytes. If pending_bytes > 0, go through below steps.
>> c. read data_offset - indicates kernel driver to write data to staging
>> buffer.
>> d. read data_size - amount of data in bytes written by vendor driver in
>> migration region.
>> e. read data_size bytes of data from data_offset in the migration region.
>> f. Write data packet as below:
>> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data}
>> g. iterate through steps b to f while (pending_bytes > 0)
>> h. Write {VFIO_MIG_FLAG_END_OF_STATE}
>>
>> When data region is mapped, its user's responsibility to read data from
>> data_offset of data_size before moving to next steps.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> ---
>> hw/vfio/migration.c | 245 +++++++++++++++++++++++++++++++++++++++++-
>> hw/vfio/trace-events | 6 ++
>> include/hw/vfio/vfio-common.h | 1 +
>> 3 files changed, 251 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
>> index 033f76526e49..ecbeed5182c2 100644
>> --- a/hw/vfio/migration.c
>> +++ b/hw/vfio/migration.c
>> @@ -138,6 +138,137 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask,
>> return 0;
>> }
>>
>> +static void *find_data_region(VFIORegion *region,
>> + uint64_t data_offset,
>> + uint64_t data_size)
>> +{
>> + void *ptr = NULL;
>> + int i;
>> +
>> + for (i = 0; i < region->nr_mmaps; i++) {
>> + if ((data_offset >= region->mmaps[i].offset) &&
>> + (data_offset < region->mmaps[i].offset + region->mmaps[i].size) &&
>> + (data_size <= region->mmaps[i].size)) {
>> + ptr = region->mmaps[i].mmap + (data_offset -
>> + region->mmaps[i].offset);
>> + break;
>> + }
>> + }
>> + return ptr;
>> +}
>> +
>> +static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev)
>> +{
>> + VFIOMigration *migration = vbasedev->migration;
>> + VFIORegion *region = &migration->region;
>> + uint64_t data_offset = 0, data_size = 0;
>> + int ret;
>> +
>> + ret = pread(vbasedev->fd, &data_offset, sizeof(data_offset),
>> + region->fd_offset + offsetof(struct vfio_device_migration_info,
>> + data_offset));
>> + if (ret != sizeof(data_offset)) {
>> + error_report("%s: Failed to get migration buffer data offset %d",
>> + vbasedev->name, ret);
>> + return -EINVAL;
>> + }
>> +
>> + ret = pread(vbasedev->fd, &data_size, sizeof(data_size),
>> + region->fd_offset + offsetof(struct vfio_device_migration_info,
>> + data_size));
>> + if (ret != sizeof(data_size)) {
>> + error_report("%s: Failed to get migration buffer data size %d",
>> + vbasedev->name, ret);
>> + return -EINVAL;
>> + }
> data_size should be read first, and if it's 0, data_offset will not
> be read further.
>
> the reasons are below:
> 1. if there's no data region provided by vendor driver, there's no
> reason to get a valid data_offset, so reading/writing of data_offset
> should fail. And this should not be treated as a migration error.
>
> 2. even if pending_bytes is 0, vfio_save_iterate() is still possible to be
> called and therefore vfio_save_buffer() is called.
>
As I mentioned in reply to Alex in:
https://lists.nongnu.org/archive/html/qemu-devel/2020-05/msg02476.html
With that, vfio_save_iterate() will read pending_bytes if its 0 and then
if pending_bytes is not 0 then call vfio_save_buffer(). With that your
above concerns should get resolved.
Thanks,
Kirti
next prev parent reply other threads:[~2020-05-11 10:23 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 21:08 [PATCH v16 QEMU 00/16] Add migration support for VFIO devices Kirti Wankhede
2020-03-24 21:08 ` [PATCH v16 QEMU 01/16] vfio: KABI for migration interface - Kernel header placeholder Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 02/16] vfio: Add function to unmap VFIO region Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 03/16] vfio: Add vfio_get_object callback to VFIODeviceOps Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 04/16] vfio: Add save and load functions for VFIO PCI devices Kirti Wankhede
2020-03-25 19:56 ` Alex Williamson
2020-03-26 17:29 ` Dr. David Alan Gilbert
2020-03-26 17:38 ` Alex Williamson
2020-05-04 23:18 ` Kirti Wankhede
2020-05-05 4:37 ` Alex Williamson
2020-05-06 6:11 ` Yan Zhao
2020-05-06 19:48 ` Kirti Wankhede
2020-05-06 20:03 ` Alex Williamson
2020-05-07 5:40 ` Kirti Wankhede
2020-05-07 18:14 ` Alex Williamson
2020-03-26 17:46 ` Dr. David Alan Gilbert
2020-05-04 23:19 ` Kirti Wankhede
2020-04-07 4:10 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2020-05-04 23:21 ` Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 05/16] vfio: Add migration region initialization and finalize function Kirti Wankhede
2020-03-26 17:52 ` Dr. David Alan Gilbert
2020-05-04 23:19 ` Kirti Wankhede
2020-05-19 19:32 ` Dr. David Alan Gilbert
2020-03-24 21:09 ` [PATCH v16 QEMU 06/16] vfio: Add VM state change handler to know state of VM Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 07/16] vfio: Add migration state change notifier Kirti Wankhede
2020-04-01 11:27 ` Dr. David Alan Gilbert
2020-05-04 23:20 ` Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 08/16] vfio: Register SaveVMHandlers for VFIO device Kirti Wankhede
2020-03-25 21:02 ` Alex Williamson
2020-05-04 23:19 ` Kirti Wankhede
2020-05-05 4:37 ` Alex Williamson
2020-05-06 6:38 ` Yan Zhao
2020-05-06 9:58 ` Cornelia Huck
2020-05-06 16:53 ` Dr. David Alan Gilbert
2020-05-06 19:30 ` Kirti Wankhede
2020-05-07 6:37 ` Cornelia Huck
2020-05-07 20:29 ` Alex Williamson
2020-04-01 17:36 ` Dr. David Alan Gilbert
2020-05-04 23:20 ` Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 09/16] vfio: Add save state functions to SaveVMHandlers Kirti Wankhede
2020-03-25 22:03 ` Alex Williamson
2020-05-04 23:18 ` Kirti Wankhede
2020-05-05 4:37 ` Alex Williamson
2020-05-11 9:53 ` Kirti Wankhede
2020-05-11 15:59 ` Alex Williamson
2020-05-12 2:06 ` Yan Zhao
2020-05-09 5:31 ` Yan Zhao
2020-05-11 10:22 ` Kirti Wankhede [this message]
2020-05-12 0:50 ` Yan Zhao
2020-03-24 21:09 ` [PATCH v16 QEMU 10/16] vfio: Add load " Kirti Wankhede
2020-03-25 22:36 ` Alex Williamson
2020-04-01 18:58 ` Dr. David Alan Gilbert
2020-05-04 23:20 ` Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 11/16] iommu: add callback to get address limit IOMMU supports Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 12/16] memory: Set DIRTY_MEMORY_MIGRATION when IOMMU is enabled Kirti Wankhede
2020-04-01 19:00 ` Dr. David Alan Gilbert
2020-04-01 19:42 ` Alex Williamson
2020-03-24 21:09 ` [PATCH v16 QEMU 13/16] vfio: Add function to start and stop dirty pages tracking Kirti Wankhede
2020-03-26 19:10 ` Alex Williamson
2020-05-04 23:20 ` Kirti Wankhede
2020-04-01 19:03 ` Dr. David Alan Gilbert
2020-05-04 23:21 ` Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 14/16] vfio: Add vfio_listener_log_sync to mark dirty pages Kirti Wankhede
2020-03-25 2:19 ` Yan Zhao
2020-03-26 19:46 ` Alex Williamson
2020-04-01 19:08 ` Dr. David Alan Gilbert
2020-04-01 5:50 ` Yan Zhao
2020-04-03 20:11 ` Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 15/16] vfio: Add ioctl to get dirty pages bitmap during dma unmap Kirti Wankhede
2020-03-24 21:09 ` [PATCH v16 QEMU 16/16] vfio: Make vfio-pci device migration capable Kirti Wankhede
2020-03-24 23:36 ` [PATCH v16 QEMU 00/16] Add migration support for VFIO devices no-reply
2020-03-31 18:34 ` Alex Williamson
2020-04-01 6:41 ` Yan Zhao
2020-04-01 18:34 ` Alex Williamson
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