On 1/22/2021 4:22 PM, Alex Williamson wrote:
> On Tue, 19 Jan 2021 09:48:24 -0800
> Steve Sistare <steven.sistare@xxxxxxxxxx> wrote:
>
>> Implement VFIO_DMA_UNMAP_FLAG_ALL.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@xxxxxxxxxx>
>> ---
>> drivers/vfio/vfio_iommu_type1.c | 22 +++++++++++++++++-----
>> 1 file changed, 17 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>> index c687174..ef83018 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -1100,6 +1100,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>> unsigned long pgshift;
>> dma_addr_t iova = unmap->iova;
>> unsigned long size = unmap->size;
>> + bool unmap_all = !!(unmap->flags & VFIO_DMA_UNMAP_FLAG_ALL);
>>
>> mutex_lock(&iommu->lock);
>>
>> @@ -1109,8 +1110,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>> if (iova & (pgsize - 1))
>> goto unlock;
>>
>> - if (!size || size & (pgsize - 1))
>> + if (unmap_all) {
>> + if (iova || size)
>> + goto unlock;
>> + size = SIZE_MAX;
>> + } else if (!size || size & (pgsize - 1)) {
>> goto unlock;
>> + }
>>
>> if (iova + size - 1 < iova || size > SIZE_MAX)
>> goto unlock;
>> @@ -1154,7 +1160,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>> * will only return success and a size of zero if there were no
>> * mappings within the range.
>> */
>> - if (iommu->v2) {
>> + if (iommu->v2 && !unmap_all) {
>> dma = vfio_find_dma(iommu, iova, 1);
>> if (dma && dma->iova != iova)
>> goto unlock;
>> @@ -1165,7 +1171,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>> }
>>
>> ret = 0;
>> - while ((dma = vfio_find_dma(iommu, iova, size))) {
>> + while ((dma = vfio_find_dma_first(iommu, iova, size))) {
>
>
> Why is this necessary? Isn't vfio_find_dma_first() O(logN) for this
> operation while vfio_find_dma() is O(1)?
True, vfio_find_dma is O(1) for unmap-all, and find-first is not needed until a later patch.
I'll continue discussing this issue in my response to your next email.
>> if (!iommu->v2 && iova > dma->iova)
>> break;
>> /*
>> @@ -2538,6 +2544,7 @@ static int vfio_iommu_type1_check_extension(struct vfio_iommu *iommu,
>> case VFIO_TYPE1_IOMMU:
>> case VFIO_TYPE1v2_IOMMU:
>> case VFIO_TYPE1_NESTING_IOMMU:
>> + case VFIO_UNMAP_ALL:
>> return 1;
>> case VFIO_DMA_CC_IOMMU:
>> if (!iommu)
>> @@ -2710,6 +2717,8 @@ static int vfio_iommu_type1_unmap_dma(struct vfio_iommu *iommu,
>> {
>> struct vfio_iommu_type1_dma_unmap unmap;
>> struct vfio_bitmap bitmap = { 0 };
>> + uint32_t mask = VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP |
>> + VFIO_DMA_UNMAP_FLAG_ALL;
>> unsigned long minsz;
>> int ret;
>>
>> @@ -2718,8 +2727,11 @@ static int vfio_iommu_type1_unmap_dma(struct vfio_iommu *iommu,
>> if (copy_from_user(&unmap, (void __user *)arg, minsz))
>> return -EFAULT;
>>
>> - if (unmap.argsz < minsz ||
>> - unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP)
>> + if (unmap.argsz < minsz || unmap.flags & ~mask)
>> + return -EINVAL;
>> +
>> + if ((unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
>> + (unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP))
>
> Somehow we're jumping from unmap-all and dirty-bitmap being mutually
> exclusive to dirty-bitmap is absolutely exclusive, which seems like a
> future bug or maintenance issue. Let's just test specifically what
> we're deciding is unsupported. Thanks,
OK, I will make it future proof.
- Steve
return -EINVAL;
>>
>> if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) {
>
