Hi Marek,
On 24/11/16 11:20, Marek Szyprowski wrote:
> This patch adds default_domain check before calling
> exynos_iommu_detach_device. This path was intended only to cope with
> default domains, which are automatically attached by the iommu core, so
> return error if user tries to attach device, which is already attached
> to other (non-default) domain.
I think this only applies to the current state of 32-bit ARM, where the
initial allocation of a default domain fails without CONFIG_IOMMU_DMA.
Since the device has a group, iommu_attach_device() will end up calling
into __iommu_attach_group(), which does this check before calling the
driver's .attach_dev:
if (group->default_domain && group->domain != group->default_domain)
return -EBUSY;
which if group->default_domain is non-NULL would make the new check
below redundant unless owner->domain can change independently of
dev->iommu_group->domain, but that sounds like it would be a bigger
problem anyway.
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> drivers/iommu/exynos-iommu.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 426b1534d4d3..63d9358a6d9c 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -859,8 +859,17 @@ static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
> if (!has_sysmmu(dev))
> return -ENODEV;
>
> - if (owner->domain)
> + if (owner->domain) {
> + struct iommu_group *group = iommu_group_get(dev);
> +
> + if (!group ||
> + owner->domain != iommu_group_default_domain(group)) {
Similarly, I think this prevents reattaching to a default domain from
iommu_detach_device(), since __iommu_detach_group() won't call
.detach_dev first if default_domain is non-NULL, therefore owner->domain
is presumably still pointing to the outgoing non-default domain.
Robin.
> + iommu_group_put(group);
> + return -EINVAL;
> + }
> + iommu_group_put(group);
> exynos_iommu_detach_device(owner->domain, dev);
> + }
>
> mutex_lock(&owner->rpm_lock);
>
>
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