lkml.org 
[lkml]   [2021]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] iommu: Fix race condition during default domain allocation
On Thu, Jun 10, 2021 at 09:46:53AM +0530, Ashish Mhetre wrote:
> Domain is getting created more than once during asynchronous multiple
> display heads(devices) probe. All the display heads share same SID and
> are expected to be in same domain. As iommu_alloc_default_domain() call
> is not protected, the group->default_domain and group->domain are ending
> up with different domains and leading to subsequent IOMMU faults.
> Fix this by protecting iommu_alloc_default_domain() call with group->mutex.

Can you provide some more information about exactly what the h/w
configuration is, and the callstack which exhibits the race, please?

> Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
> ---
> drivers/iommu/iommu.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 808ab70..2700500 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -273,7 +273,9 @@ int iommu_probe_device(struct device *dev)
> * support default domains, so the return value is not yet
> * checked.
> */
> + mutex_lock(&group->mutex);
> iommu_alloc_default_domain(group, dev);
> + mutex_unlock(&group->mutex);

It feels wrong to serialise this for everybody just to cater for systems
with aliasing SIDs between devices.

Will

\
 
 \ /
  Last update: 2021-06-11 12:46    [W:0.050 / U:0.124 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site