Re: [PATCH v2 10/16] iommu: Restore and reattach preserved domains to devices

[Samiullah Khawaja]

On Fri, May 29, 2026 at 04:43:42PM +0000, Ankit Soni wrote:
> On Mon, Apr 27, 2026 at 05:56:27PM +0000, Samiullah Khawaja wrote:
> > Restore the preserved domains by restoring the page tables using restore
> > IOMMU domain op. Reattach the preserved domain to the device during
> > default domain setup. While attaching, reuse the domain ID that was used
> > in the previous kernel. The context entry setup is not needed as that is
> > preserved during liveupdate.
> >
> > Signed-off-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>
> > ---
> >  drivers/iommu/intel/iommu.c      | 49 ++++++++++++++------
> >  drivers/iommu/intel/iommu.h      |  3 +-
> >  drivers/iommu/intel/nested.c     |  2 +-
> >  drivers/iommu/iommu.c            | 61 ++++++++++++++++++++++++-
> >  drivers/iommu/liveupdate.c       | 78 ++++++++++++++++++++++++++++++++
> >  include/linux/iommu-liveupdate.h | 50 ++++++++++++++++++++
> >  6 files changed, 224 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 4118a0861f38..b90757164cd8 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -1031,7 +1031,8 @@ static bool first_level_by_default(struct intel_iommu *iommu)
> >  	return true;
> >  }
> >
> > -int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
> > +int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu,
> > +			int restore_did)
> >  {
> >  	struct iommu_domain_info *info, *curr;
> >  	int num, ret = -ENOSPC;
> > @@ -1051,8 +1052,11 @@ int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
> >  		return 0;
> >  	}
> >
> > -	num = ida_alloc_range(&iommu->domain_ida, IDA_START_DID,
> > -			      cap_ndoms(iommu->cap) - 1, GFP_KERNEL);
> > +	if (restore_did >= IDA_START_DID)
> > +		num = restore_did;
> > +	else
> > +		num = ida_alloc_range(&iommu->domain_ida, IDA_START_DID,
> > +				      cap_ndoms(iommu->cap) - 1, GFP_KERNEL);
> >  	if (num < 0) {
> >  		pr_err("%s: No free domain ids\n", iommu->name);
> >  		goto err_unlock;
> > @@ -1320,10 +1324,14 @@ static int dmar_domain_attach_device(struct dmar_domain *domain,
> >  {
> >  	struct device_domain_info *info = dev_iommu_priv_get(dev);
> >  	struct intel_iommu *iommu = info->iommu;
> > +	struct device_ser *device_ser = NULL;
>
> Typo here? iommu_device_ser.
> compiles because dev_iommu_restored_state() returns void * and the
> variable is only null-checked, never dereferenced.

Agreed. Will update this.
> Ankit
>
> >  	unsigned long flags;
> >  	int ret;
> >
> > -	ret = domain_attach_iommu(domain, iommu);
> > +	device_ser = dev_iommu_restored_state(dev);
> > +
> > +	ret = domain_attach_iommu(domain, iommu,
> > +				  dev_iommu_restore_did(dev, &domain->domain));
> >  	if (ret)
> >  		return ret;

[snip]
> >  static inline struct iommu_hw_ser *iommu_get_preserved_data(u64 token, enum iommu_type_ser type)
> >  {
> >  	return NULL;
> > --
> > 2.54.0.545.g6539524ca2-goog

Thanks,
Sami