Re: Regression on linux-next (next-20250321)

[Nicolin Chen <nicolinc@nvidia.com>]

Hi Chaitanya,

On Wed, Mar 26, 2025 at 08:31:15AM +0000, Borah, Chaitanya Kumar wrote:
> > > `````````````````````````````````````````````````````````````````````````````````
> > > <4>[    0.226495] Unpatched return thunk in use. This should not happen!
> > > <4>[    0.226502] WARNING: CPU: 0 PID: 1 at
> > arch/x86/kernel/cpu/bugs.c:3107 __warn_thunk+0x62/0x70
> > 
> > Hmm....I wonder why x86 can be affected...
> > 
> > The only four callers of iommu_dma_prepare_msi() are ARM platforms.
[...]
> > > Details log can be found in [3].
> > 
> > And I can't see something obvious from the log..
> > 
> > Would you please give the git-diff a try (drivers/iommu/iommu.c)?
> > https://lore.kernel.org/linux-iommu/Z+Itnw4ys6dmDsc+@nvidia.com/
> > 
> > If this doesn't help, would you please give this a try?
> > https://lore.kernel.org/linux-iommu/20250324170743.GA1339275@ax162/
> > 
> 
> Thank you, Nicolin, for your reply. Unfortunately, these changes
> does not solve the issue. (applied individually and together)

Would you please try the latest linux-next (next-20250326) and see
if the issue still occurs?

If it does occur with next-20250326, would you please try reverting
06d54f00f3f5a on top of the tree rather than bisect?
 "06d54f00f3f5 iommu: Drop sw_msi from iommu_domain"

It still feels odd to me and Jason that this change would break x86.
So, we want to confirm that this is really the culprit.

Also, I think your platform doesn't set CONFIG_IRQ_MSI_IOMMU, would
you please check you .config file and confirm?

Thanks
Nicolin