On 2021/1/12 5:49, Alex Williamson wrote:
> On Thu, 7 Jan 2021 17:29:00 +0800
> Keqian Zhu <zhukeqi...@huawei.com> wrote:
>
>> If we detach group during dirty page tracking, we shouldn't remove
>> vfio_dma, because dirty log will lose.
>>
>> But we don't prevent unmap_unpin_all in vfio_iommu_release, because
>> under normal procedure, dirty tracking has been stopped.
>
> This looks like it's creating a larger problem than it's fixing, it's
> not our job to maintain the dirty bitmap regardless of what the user
> does. If the user detaches the last group in a container causing the
> mappings within that container to be deconstructed before the user has
> collected dirty pages, that sounds like a user error. A container with
> no groups is de-privileged and therefore loses all state. Thanks,
>
> Alex
Hi Alex,
This looks good to me ;-). That's a reasonable constraint for user behavior.
What about replacing this patch with an addition to the uapi document of
VFIO_GROUP_UNSET_CONTAINER? User should pay attention to this when call this
ioctl during dirty tracking.
And any comments on other patches? thanks.
Thanks.
Keqian
>
>> Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages
>> tracking")
>> Signed-off-by: Keqian Zhu <zhukeqi...@huawei.com>
>> ---
>> drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++--
>> 1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c
>> b/drivers/vfio/vfio_iommu_type1.c
>> index 26b7eb2a5cfc..9776a059904d 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -2373,7 +2373,12 @@ static void vfio_iommu_type1_detach_group(void
>> *iommu_data,
>> if (list_empty(&iommu->external_domain->group_list)) {
>> vfio_sanity_check_pfn_list(iommu);
>>
>> - if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
>> + /*
>> + * During dirty page tracking, we can't remove
>> + * vfio_dma because dirty log will lose.
>> + */
>> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) &&
>> + !iommu->dirty_page_tracking)
>> vfio_iommu_unmap_unpin_all(iommu);
>>
>> kfree(iommu->external_domain);
>> @@ -2406,10 +2411,15 @@ static void vfio_iommu_type1_detach_group(void
>> *iommu_data,
>> * iommu and external domain doesn't exist, then all the
>> * mappings go away too. If it's the last domain with iommu and
>> * external domain exist, update accounting
>> + *
>> + * Note: During dirty page tracking, we can't remove vfio_dma
>> + * because dirty log will lose. Just update accounting is a good
>> + * choice.
>> */
>> if (list_empty(&domain->group_list)) {
>> if (list_is_singular(&iommu->domain_list)) {
>> - if (!iommu->external_domain)
>> + if (!iommu->external_domain &&
>> + !iommu->dirty_page_tracking)
>> vfio_iommu_unmap_unpin_all(iommu);
>> else
>> vfio_iommu_unmap_unpin_reaccount(iommu);
>
> .
>
