Re: [PATCH v13 11/15] vfio/type1: Handle unmap/unpin and replay for VFIO_IOVA_RESERVED slots

Auger Eric
2016-10-07T17:12:25Z

Hi Alex,

On 06/10/2016 22:19, Alex Williamson wrote:
> On Thu, 6 Oct 2016 08:45:27 +0000
> Eric Auger <eric.auger@redhat.com> 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, reserved 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, by the MSI layer which
>> is responsible to free and unmap them. The MSI mapping resources are freeed
>
> nit, extra 'e', "freed"
>
>> by the IOMMU driver on domain destruction.
>>
>> On the creation of a new domain, the "replay" of a reserved slot simply
>> needs to set the MSI aperture on the new domain.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>> v12 -> v13:
>> - use dma-iommu iommu_get_dma_msi_region_cookie
>>
>> v9 -> v10:
>> - replay of a reserved slot sets the MSI aperture on the new domain
>> - use VFIO_IOVA_RESERVED_MSI enum value instead of VFIO_IOVA_RESERVED
>>
>> v7 -> v8:
>> - do no destroy anything anymore, just bypass unmap/unpin and iommu_map
>> on replay
>> ---
>> drivers/vfio/Kconfig | 1 +
>> drivers/vfio/vfio_iommu_type1.c | 10 +++++++++-
>> 2 files changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
>> index da6e2ce..673ec79 100644
>> --- a/drivers/vfio/Kconfig
>> +++ b/drivers/vfio/Kconfig
>> @@ -1,6 +1,7 @@
>> config VFIO_IOMMU_TYPE1
>> tristate
>> depends on VFIO
>> + select IOMMU_DMA
>> default n
>>
>> config VFIO_IOMMU_SPAPR_TCE
>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>> index 65a4038..5bc5fc9 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -36,6 +36,7 @@
>> #include <linux/uaccess.h>
>> #include <linux/vfio.h>
>> #include <linux/workqueue.h>
>> +#include <linux/dma-iommu.h>
>>
>> #define DRIVER_VERSION "0.2"
>> #define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>"
>> @@ -387,7 +388,7 @@ 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
>> @@ -724,6 +725,13 @@ 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_MSI) {
>> + ret = iommu_get_dma_msi_region_cookie(domain->domain,
>> + dma->iova, dma->size);
>> + WARN_ON(ret);
>> + continue;
>> + }
>
> Why is this a passable error? We consider an iommu_map() error on any
> entry a failure.
Yes I agree.

Thanks

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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