linux-kernel - RE: [PATCH 9/9] iommu/vt-d: Clean up PASID talbe management for SVM

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Date:   Tue, 1 May 2018 09:24:24 +0000
From:   "Liu, Yi L" <yi.l.liu@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>
CC:     "Raj, Ashok" <ashok.raj@...el.com>,
        "Kumar, Sanjay K" <sanjay.k.kumar@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        "Sun, Yi Y" <yi.y.sun@...el.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: RE: [PATCH 9/9] iommu/vt-d: Clean up PASID talbe management for SVM

> From: Lu Baolu [mailto:baolu.lu@...ux.intel.com]
> Sent: Tuesday, April 17, 2018 11:03 AM
> 
> The previous per iommu pasid table alloc/free interfaces
> are no longer used. Clean up the driver by removing it.

I think this patch major cleans intel_svm_alloc_pasid_tables
and intel_svm_free_pasid_tables. Actually, only PASID State
table allocation is remained in these two functions.

Since PASID Table is modified to be per-iommu domain. How
about the PASID State Table? Should it also be per-iommu domain?

Thanks,
Yi Liu
> Cc: Ashok Raj <ashok.raj@...el.com>
> Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Cc: Kevin Tian <kevin.tian@...el.com>
> Cc: Liu Yi L <yi.l.liu@...el.com>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/intel-iommu.c |  6 +++---
>  drivers/iommu/intel-svm.c   | 17 ++---------------
>  include/linux/intel-iommu.h |  5 ++---
>  3 files changed, 7 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 5fe7f91..5acb90d 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -1736,7 +1736,7 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
>  	if (pasid_enabled(iommu)) {
>  		if (ecap_prs(iommu->ecap))
>  			intel_svm_finish_prq(iommu);
> -		intel_svm_free_pasid_tables(iommu);
> +		intel_svm_exit(iommu);
>  	}
>  #endif
>  }
> @@ -3291,7 +3291,7 @@ static int __init init_dmars(void)
>  			hw_pass_through = 0;
>  #ifdef CONFIG_INTEL_IOMMU_SVM
>  		if (pasid_enabled(iommu))
> -			intel_svm_alloc_pasid_tables(iommu);
> +			intel_svm_init(iommu);
>  #endif
>  	}
> 
> @@ -4268,7 +4268,7 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
> 
>  #ifdef CONFIG_INTEL_IOMMU_SVM
>  	if (pasid_enabled(iommu))
> -		intel_svm_alloc_pasid_tables(iommu);
> +		intel_svm_init(iommu);
>  #endif
> 
>  	if (dmaru->ignored) {
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index 3b14819..38cae65 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -34,7 +34,7 @@
> 
>  static irqreturn_t prq_event_thread(int irq, void *d);
> 
> -int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu)
> +int intel_svm_init(struct intel_iommu *iommu)
>  {
>  	struct page *pages;
>  	int order;
> @@ -59,15 +59,6 @@ int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu)
>  		iommu->pasid_max = 0x20000;
> 
>  	order = get_order(sizeof(struct pasid_entry) * iommu->pasid_max);
> -	pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
> -	if (!pages) {
> -		pr_warn("IOMMU: %s: Failed to allocate PASID table\n",
> -			iommu->name);
> -		return -ENOMEM;
> -	}
> -	iommu->pasid_table = page_address(pages);
> -	pr_info("%s: Allocated order %d PASID table.\n", iommu->name, order);
> -
>  	if (ecap_dis(iommu->ecap)) {
>  		/* Just making it explicit... */
>  		BUILD_BUG_ON(sizeof(struct pasid_entry) != sizeof(struct
> pasid_state_entry));
> @@ -82,14 +73,10 @@ int intel_svm_alloc_pasid_tables(struct intel_iommu
> *iommu)
>  	return 0;
>  }
> 
> -int intel_svm_free_pasid_tables(struct intel_iommu *iommu)
> +int intel_svm_exit(struct intel_iommu *iommu)
>  {
>  	int order = get_order(sizeof(struct pasid_entry) * iommu->pasid_max);
> 
> -	if (iommu->pasid_table) {
> -		free_pages((unsigned long)iommu->pasid_table, order);
> -		iommu->pasid_table = NULL;
> -	}
>  	if (iommu->pasid_state_table) {
>  		free_pages((unsigned long)iommu->pasid_state_table, order);
>  		iommu->pasid_state_table = NULL;
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 08e5811..44c7613 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -470,7 +470,6 @@ struct intel_iommu {
>  	 * devices away to userspace processes (e.g. for DPDK) and don't
>  	 * want to trust that userspace will use *only* the PASID it was
>  	 * told to. But while it's all driver-arbitrated, we're fine. */
> -	struct pasid_entry *pasid_table;
>  	struct pasid_state_entry *pasid_state_table;
>  	struct page_req_dsc *prq;
>  	unsigned char prq_name[16];    /* Name for PRQ interrupt */
> @@ -539,8 +538,8 @@ void free_pgtable_page(void *vaddr);
>  struct intel_iommu *domain_get_iommu(struct dmar_domain *domain);
> 
>  #ifdef CONFIG_INTEL_IOMMU_SVM
> -extern int intel_svm_alloc_pasid_tables(struct intel_iommu *iommu);
> -extern int intel_svm_free_pasid_tables(struct intel_iommu *iommu);
> +int intel_svm_init(struct intel_iommu *iommu);
> +int intel_svm_exit(struct intel_iommu *iommu);
>  extern int intel_svm_enable_prq(struct intel_iommu *iommu);
>  extern int intel_svm_finish_prq(struct intel_iommu *iommu);
> 
> --
> 2.7.4