linux-kernel - Re: [PATCH v3 1/1] iommu/sva: Invalidate KVA range on kernel TLB flush

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Message-ID: <20250811125753.GT184255@nvidia.com>
Date: Mon, 11 Aug 2025 09:57:53 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>
Cc: Dave Hansen <dave.hansen@...el.com>, Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
	Kevin Tian <kevin.tian@...el.com>, Jann Horn <jannh@...gle.com>,
	Vasant Hegde <vasant.hegde@....com>,
	Alistair Popple <apopple@...dia.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Andy Lutomirski <luto@...nel.org>, Yi Lai <yi1.lai@...el.com>,
	iommu@...ts.linux.dev, security@...nel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v3 1/1] iommu/sva: Invalidate KVA range on kernel TLB
 flush

On Fri, Aug 08, 2025 at 01:15:12PM +0800, Baolu Lu wrote:
> +static void kernel_pte_work_func(struct work_struct *work)
> +{
> +	struct ptdesc *ptdesc, *next;
> +
> +	iommu_sva_invalidate_kva_range(0, TLB_FLUSH_ALL);
> +
> +	guard(spinlock)(&kernel_pte_work.lock);
> +	list_for_each_entry_safe(ptdesc, next, &kernel_pte_work.list, pt_list) {
> +		list_del_init(&ptdesc->pt_list);
> +		pagetable_dtor_free(ptdesc);
> +	}

Do a list_move from kernel_pte_work.list to an on-stack list head and
then immediately release the lock. No reason to hold the spinock while
doing frees, also no reason to do list_del_init, that memory probably
gets zerod in pagetable_dtor_free()

Jason