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Date:   Tue, 2 Feb 2021 10:22:05 -0700
From:   Alex Williamson <alex.williamson@redhat.com>
To:     Keqian Zhu <zhukeqian1@huawei.com>
Cc:     <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <kvm@vger.kernel.org>,
        <kvmarm@lists.cs.columbia.edu>, <iommu@lists.linux-foundation.org>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        "Cornelia Huck" <cohuck@redhat.com>, Will Deacon <will@kernel.org>,
        Marc Zyngier <maz@kernel.org>,
        "Catalin Marinas" <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        "James Morse" <james.morse@arm.com>,
        Robin Murphy <robin.murphy@arm.com>,
        "Joerg Roedel" <joro@8bytes.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexios Zavras <alexios.zavras@intel.com>,
        <wanghaibin.wang@huawei.com>, <jiangkunkun@huawei.com>
Subject: Re: [PATCH] vfio/iommu_type1: Mantainance a counter for
 non_pinned_groups
Message-ID: <20210202102205.54737110@omen.home.shazbot.org>
In-Reply-To: <20210125024642.14604-1-zhukeqian1@huawei.com>
References: <20210125024642.14604-1-zhukeqian1@huawei.com>
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On Mon, 25 Jan 2021 10:46:42 +0800
Keqian Zhu <zhukeqian1@huawei.com> wrote:

> With this counter, we never need to traverse all groups to update
> pinned_scope of vfio_iommu.
> 
> Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 40 +++++----------------------------
>  1 file changed, 5 insertions(+), 35 deletions(-)

Applied to vfio next branch for v5.12.  Thanks,

Alex

> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 0b4dedaa9128..bb4bbcc79101 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -73,7 +73,7 @@ struct vfio_iommu {
>  	bool			v2;
>  	bool			nesting;
>  	bool			dirty_page_tracking;
> -	bool			pinned_page_dirty_scope;
> +	uint64_t		num_non_pinned_groups;
>  };
>  
>  struct vfio_domain {
> @@ -148,7 +148,6 @@ static int put_pfn(unsigned long pfn, int prot);
>  static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
>  					       struct iommu_group *iommu_group);
>  
> -static void update_pinned_page_dirty_scope(struct vfio_iommu *iommu);
>  /*
>   * This code handles mapping and unmapping of user data buffers
>   * into DMA'ble space using the IOMMU
> @@ -714,7 +713,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>  	group = vfio_iommu_find_iommu_group(iommu, iommu_group);
>  	if (!group->pinned_page_dirty_scope) {
>  		group->pinned_page_dirty_scope = true;
> -		update_pinned_page_dirty_scope(iommu);
> +		iommu->num_non_pinned_groups--;
>  	}
>  
>  	goto pin_done;
> @@ -991,7 +990,7 @@ static int update_user_bitmap(u64 __user *bitmap, struct vfio_iommu *iommu,
>  	 * mark all pages dirty if any IOMMU capable device is not able
>  	 * to report dirty pages and all pages are pinned and mapped.
>  	 */
> -	if (!iommu->pinned_page_dirty_scope && dma->iommu_mapped)
> +	if (iommu->num_non_pinned_groups && dma->iommu_mapped)
>  		bitmap_set(dma->bitmap, 0, nbits);
>  
>  	if (shift) {
> @@ -1622,33 +1621,6 @@ static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
>  	return group;
>  }
>  
> -static void update_pinned_page_dirty_scope(struct vfio_iommu *iommu)
> -{
> -	struct vfio_domain *domain;
> -	struct vfio_group *group;
> -
> -	list_for_each_entry(domain, &iommu->domain_list, next) {
> -		list_for_each_entry(group, &domain->group_list, next) {
> -			if (!group->pinned_page_dirty_scope) {
> -				iommu->pinned_page_dirty_scope = false;
> -				return;
> -			}
> -		}
> -	}
> -
> -	if (iommu->external_domain) {
> -		domain = iommu->external_domain;
> -		list_for_each_entry(group, &domain->group_list, next) {
> -			if (!group->pinned_page_dirty_scope) {
> -				iommu->pinned_page_dirty_scope = false;
> -				return;
> -			}
> -		}
> -	}
> -
> -	iommu->pinned_page_dirty_scope = true;
> -}
> -
>  static bool vfio_iommu_has_sw_msi(struct list_head *group_resv_regions,
>  				  phys_addr_t *base)
>  {
> @@ -2057,8 +2029,6 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  			 * addition of a dirty tracking group.
>  			 */
>  			group->pinned_page_dirty_scope = true;
> -			if (!iommu->pinned_page_dirty_scope)
> -				update_pinned_page_dirty_scope(iommu);
>  			mutex_unlock(&iommu->lock);
>  
>  			return 0;
> @@ -2188,7 +2158,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	 * demotes the iommu scope until it declares itself dirty tracking
>  	 * capable via the page pinning interface.
>  	 */
> -	iommu->pinned_page_dirty_scope = false;
> +	iommu->num_non_pinned_groups++;
>  	mutex_unlock(&iommu->lock);
>  	vfio_iommu_resv_free(&group_resv_regions);
>  
> @@ -2416,7 +2386,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
>  	 * to be promoted.
>  	 */
>  	if (update_dirty_scope)
> -		update_pinned_page_dirty_scope(iommu);
> +		iommu->num_non_pinned_groups--;
>  	mutex_unlock(&iommu->lock);
>  }
>