Re: [PATCH v3 12/18] iommu/vt-d: Handle reattach of the restored domain

[Baolu Lu <baolu.lu@linux.intel.com>]

On 6/15/26 07:37, Samiullah Khawaja wrote:
> Reattach the restored domain to the preserved device using restored
> domain ID. While reattaching do not setup the context and PASID entries
> as those are preserved during liveupdate.
> 
> Signed-off-by: Samiullah Khawaja<skhawaja@google.com>
> ---
>   drivers/iommu/intel/iommu.c      |  46 ++++++++++---
>   drivers/iommu/intel/iommu.h      |  17 +++++
>   drivers/iommu/intel/liveupdate.c | 111 +++++++++++++++++++++++++++++++
>   3 files changed, 163 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index cd40e274482b..91b67ccba011 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1311,10 +1311,16 @@ 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 iommu_device_ser *device_ser;
>   	unsigned long flags;
>   	int ret;
>   
> -	ret = domain_attach_iommu(domain, iommu);
> +	device_ser = dev_iommu_restored_state(dev);
> +	if (!device_ser)
> +		ret = domain_attach_iommu(domain, iommu);
> +	else
> +		ret = intel_iommu_domain_reattach_iommu(domain,
> +							iommu, device_ser);
>   	if (ret)
>   		return ret;
>   
> @@ -1327,16 +1333,20 @@ static int dmar_domain_attach_device(struct dmar_domain *domain,
>   	if (dev_is_real_dma_subdevice(dev))
>   		return 0;
>   
> -	if (!sm_supported(iommu))
> -		ret = domain_context_mapping(domain, dev);
> -	else if (intel_domain_is_fs_paging(domain))
> -		ret = domain_setup_first_level(iommu, domain, dev,
> -					       IOMMU_NO_PASID, NULL);
> -	else if (intel_domain_is_ss_paging(domain))
> -		ret = domain_setup_second_level(iommu, domain, dev,
> -						IOMMU_NO_PASID, NULL);
> -	else if (WARN_ON(true))
> -		ret = -EINVAL;
> +	if (!device_ser) {
> +		if (!sm_supported(iommu))
> +			ret = domain_context_mapping(domain, dev);
> +		else if (intel_domain_is_fs_paging(domain))
> +			ret = domain_setup_first_level(iommu, domain, dev,
> +						       IOMMU_NO_PASID, NULL);
> +		else if (intel_domain_is_ss_paging(domain))
> +			ret = domain_setup_second_level(iommu, domain, dev,
> +							IOMMU_NO_PASID, NULL);
> +		else if (WARN_ON(true))
> +			ret = -EINVAL;
> +	} else if (!sm_supported(iommu)) {
> +		iommu_enable_pci_ats(info);
> +	}

Instead of merging domain restoration into the attach_dev path, how
about adding a new callback to restore a preserved domain for a device?
Something like:

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index b2f614367074..e61409f2d9fc 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -748,6 +748,8 @@ struct iommu_ops {
   * * <others>  - treated as ENODEV by the caller. Use is discouraged
   * @set_dev_pasid: set or replace an iommu domain to a pasid of 
device. The pasid of
   *                 the device should be left in the old config in 
error case.
+ * @restore_dev: Set a domain that is restored from the previous 
live-updated
+ *               kernel to a device.
   * @map_pages: map a physically contiguous set of pages of the same 
size to
   *             an iommu domain.
   * @unmap_pages: unmap a number of pages of the same size from an 
iommu domain
@@ -772,6 +774,9 @@ struct iommu_ops {
  struct iommu_domain_ops {
         int (*attach_dev)(struct iommu_domain *domain, struct device *dev,
                           struct iommu_domain *old);
+#ifdef CONFIG_IOMMU_LIVEUPDATE
+       int (*restore_dev)(struct iommu_domain *domain, struct device *dev);
+#endif
         int (*set_dev_pasid)(struct iommu_domain *domain, struct device 
*dev,
                              ioasid_t pasid, struct iommu_domain *old);

Thanks,
baolu