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

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Message-ID: <20250806164235.GY184255@nvidia.com>
Date: Wed, 6 Aug 2025 13:42:35 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Dave Hansen <dave.hansen@...el.com>
Cc: Lu Baolu <baolu.lu@...ux.intel.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 Wed, Aug 06, 2025 at 09:34:12AM -0700, Dave Hansen wrote:
> struct kernel_pgtable_work
> {
> 	struct list_head list;
> 	spinlock_t lock;
> 	struct work_struct work;
> } kernel_pte_work;
> 
> pte_free_kernel()
> {
> 	struct page *page = ptdesc_magic();
> 
> 	guard(spinlock)(&kernel_pte_work.lock);
> 	
> 	list_add(&page->list, &kernel_pte_work.list);
> 	schedule_work(&kernel_pte_work.work);
> }

Oh, OK, yeah this can work

> The only wrinkle is that pte_free_kernel() itself still has a pte and
> 'ptdesc', not a 'struct page'. But there is ptdesc->pt_list, which
> should be unused at this point, especially for non-pgd pages on x86.

It should all be ptdesc, so lets avoid a struct page here and use the
pt_list instead..

Jason