Ping? I think this needs to be a v4.0 candidate. Thanks,
Alex
On Wed, 2015-03-04 at 11:30 -0700, Alex Williamson wrote:
> Device domains never span IOMMU hardware units, which allows the
> domain ID space for each IOMMU to be an independent address space.
> Therefore we can have multiple, independent domains, each with the
> same domain->id, but attached to different hardware units. This is
> also why we need to do a heavy-weight search for VM domains since
> they can span multiple IOMMUs hardware units and we don't require a
> single global ID to use for all hardware units.
>
> Therefore, if we call iommu_detach_domain() across all active IOMMU
> hardware units for a non-VM domain, the result is that we clear domain
> IDs that are not associated with our domain, allowing them to be
> re-allocated and causing apparent coherency issues when the device
> cannot access IOVAs for the intended domain.
>
> This bug was introduced in commit fb170fb4c548 ("iommu/vt-d: Introduce
> helper functions to make code symmetric for readability"), but is
> significantly exacerbated by the more recent commit 62c22167dd70
> ("iommu/vt-d: Fix dmar_domain leak in iommu_attach_device") which calls
> domain_exit() more frequently to resolve a domain leak.
>
> Fixes: fb170fb4c548 ("iommu/vt-d: Introduce helper functions to make code
> symmetric for readability")
> Signed-off-by: Alex Williamson <[email protected]>
> Cc: Jiang Liu <[email protected]>
> Cc: [email protected] # v3.17+
> ---
> drivers/iommu/intel-iommu.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index ae4c1a8..a83c965 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -1743,8 +1743,8 @@ static int domain_init(struct dmar_domain *domain, int
> guest_width)
> static void domain_exit(struct dmar_domain *domain)
> {
> struct dmar_drhd_unit *drhd;
> - struct intel_iommu *iommu;
> struct page *freelist = NULL;
> + int i;
>
> /* Domain 0 is reserved, so dont process it */
> if (!domain)
> @@ -1764,8 +1764,8 @@ static void domain_exit(struct dmar_domain *domain)
>
> /* clear attached or cached domains */
> rcu_read_lock();
> - for_each_active_iommu(iommu, drhd)
> - iommu_detach_domain(domain, iommu);
> + for_each_set_bit(i, domain->iommu_bmp, g_num_of_iommus)
> + iommu_detach_domain(domain, g_iommus[i]);
> rcu_read_unlock();
>
> dma_free_pagelist(freelist);
>
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