[PATCH] [topic/xe-for-CI]iommu/vt-d: Enable ATS before cache tag assignment

[Upadhyay, Tejas]

Ignore the patch, does not seem to be rightly rebased. Will send another one.

Tejas

> -----Original Message-----
> From: Upadhyay, Tejas <tejas.upadhyay at intel.com>
> Sent: 24 June 2025 13:30
> To: intel-xe at lists.freedesktop.org
> Cc: Lu Baolu <baolu.lu at linux.intel.com>; Upadhyay, Tejas
> <tejas.upadhyay at intel.com>
> Subject: [PATCH] [topic/xe-for-CI]iommu/vt-d: Enable ATS before cache tag
> assignment
> 
> From: Lu Baolu <baolu.lu at linux.intel.com>
> 
> Commit <4f1492efb495> ("iommu/vt-d: Revert ATS timing change to fix boot
> failure") placed the enabling of ATS in the probe_finalize callback. This occurs
> after the default domain attachment, which is when the ATS cache tag is
> assigned. Consequently, the device TLB cache tag is missed when the domain is
> attached, leading to the device TLB not being invalidated in the iommu_unmap
> paths.
> 
> Fix it by moving the ATS enabling to the default domain attachment path,
> ensuring ATS is enabled before the cache tag assignment.
> 
> Fixes: 4f1492efb495 ("iommu/vt-d: Revert ATS timing change to fix boot
> failure")
> Signed-off-by: Lu Baolu <baolu.lu at linux.intel.com>
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay at intel.com>
> ---
>  drivers/iommu/intel/iommu.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 7aa3932251b2..863ccb47bcca 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -54,6 +54,7 @@
>  				__DOMAIN_MAX_PFN(gaw), (unsigned
> long)-1))
>  #define DOMAIN_MAX_ADDR(gaw)
> 	(((uint64_t)__DOMAIN_MAX_PFN(gaw)) << VTD_PAGE_SHIFT)
> 
> +static void sm_iommu_enable_pcicaps(struct device *dev);
>  static void __init check_tylersburg_isoch(void);  static int rwbf_quirk;
> 
> @@ -1825,10 +1826,11 @@ static int dmar_domain_attach_device(struct
> dmar_domain *domain,
>  	else
>  		ret = domain_setup_second_level(iommu, domain, dev,
>  						IOMMU_NO_PASID, NULL);
> -
>  	if (ret)
>  		goto out_block_translation;
> 
> +	/* PCI ATS enablement must happen before cache tag assigning. */
> +	sm_iommu_enable_pcicaps(dev);
>  	ret = cache_tag_assign_domain(domain, dev, IOMMU_NO_PASID);
>  	if (ret)
>  		goto out_block_translation;
> @@ -3765,11 +3767,18 @@ static struct iommu_device
> *intel_iommu_probe_device(struct device *dev)
>  	return ERR_PTR(ret);
>  }
> 
> -static void intel_iommu_probe_finalize(struct device *dev)
> +static void sm_iommu_enable_pcicaps(struct device *dev)
>  {
>  	struct device_domain_info *info = dev_iommu_priv_get(dev);
>  	struct intel_iommu *iommu = info->iommu;
> 
> +	/*
> +	 * Called only in iommu_device_register() path when iommu is
> +	 * configured in the scalable mode.
> +	 */
> +	if (!sm_supported(iommu) || READ_ONCE(iommu->iommu.ready))
> +		return;
> +
>  	/*
>  	 * The PCIe spec, in its wisdom, declares that the behaviour of the
>  	 * device is undefined if you enable PASID support after ATS support.
> @@ -3780,7 +3789,7 @@ static void intel_iommu_probe_finalize(struct
> device *dev)
>  	    !pci_enable_pasid(to_pci_dev(dev), info->pasid_supported & ~1))
>  		info->pasid_enabled = 1;
> 
> -	if (sm_supported(iommu) && !dev_is_real_dma_subdevice(dev))
> +	if (!dev_is_real_dma_subdevice(dev))
>  		iommu_enable_pci_ats(info);
>  	iommu_enable_pci_pri(info);
>  }
> @@ -4309,6 +4318,7 @@ static int identity_domain_attach_dev(struct
> iommu_domain *domain, struct device
>  		ret = intel_pasid_setup_pass_through(iommu, dev,
> IOMMU_NO_PASID);
>  	else
>  		ret = device_setup_pass_through(dev);
> +	sm_iommu_enable_pcicaps(dev);
> 
>  	if (!ret)
>  		info->domain_attached = true;
> @@ -4359,7 +4369,6 @@ const struct iommu_ops intel_iommu_ops = {
>  	.domain_alloc_sva	= intel_svm_domain_alloc,
>  	.domain_alloc_nested	= intel_iommu_domain_alloc_nested,
>  	.probe_device		= intel_iommu_probe_device,
> -	.probe_finalize		= intel_iommu_probe_finalize,
>  	.release_device		= intel_iommu_release_device,
>  	.get_resv_regions	= intel_iommu_get_resv_regions,
>  	.device_group		= intel_iommu_device_group,
> --
> 2.34.1