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SubjectRe: [PATCH v9 3/7] vfio/type1: bypass unmap/unpin and replay for VFIO_IOVA_RESERVED slots
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Hi Alex,
On 05/10/2016 12:49 AM, Alex Williamson wrote:
> On Wed, 4 May 2016 11:54:14 +0000
> Eric Auger <eric.auger@linaro.org> wrote:
>
>> Before allowing the end-user to create VFIO_IOVA_RESERVED dma slots,
>> let's implement the expected behavior for removal and replay. As opposed
>> to user dma slots, IOVAs are not systematically bound to PAs and PAs are
>> not pinned. VFIO just initializes the IOVA "aperture". IOVAs are allocated
>> outside of the VFIO framework, typically the MSI layer which is
>> responsible to free and unmap them. The MSI mapping resources are freeed
>> by the IOMMU driver on domain destruction.
>>
>> Signed-off-by: Eric Auger <eric.auger@linaro.org>
>>
>> ---
>>
>> v7 -> v8:
>> - do no destroy anything anymore, just bypass unmap/unpin and iommu_map
>> on replay
>> ---
>> drivers/vfio/vfio_iommu_type1.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>> index 2d769d4..94a9916 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -391,7 +391,7 @@ static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma)
>> struct vfio_domain *domain, *d;
>> long unlocked = 0;
>>
>> - if (!dma->size)
>> + if (!dma->size || dma->type != VFIO_IOVA_USER)
>> return;
>> /*
>> * We use the IOMMU to track the physical addresses, otherwise we'd
>> @@ -727,6 +727,9 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
>> dma = rb_entry(n, struct vfio_dma, node);
>> iova = dma->iova;
>>
>> + if (dma->type == VFIO_IOVA_RESERVED)
>> + continue;
>> +
>
> But you do still need some sort of replay mechanism, right? Not to
> replay the IOVA to PA mapping, but to call iommu_msi_set_aperture() for
> the new domain. How will you know that this entry is an MSI reserved
> range or something else? Perhaps we can't have a generic "reserved"
> type here.
Thanks for spotting this bug. I was not testing this case yet and
effectively I need to replay the set_aperture.

Thanks for the review

Best Regards

Eric

>
>> while (iova < dma->iova + dma->size) {
>> phys_addr_t phys = iommu_iova_to_phys(d->domain, iova);
>> size_t size;
>

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