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[35.207.112.95]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b8e04c7407sm36750215f8f.13.2025.08.12.20.18.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Aug 2025 20:18:05 -0700 (PDT) Message-ID: <33b39588-5a39-4474-ac17-bde923803600@gmail.com> Date: Wed, 13 Aug 2025 11:17:57 +0800 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] iommu/sva: Invalidate KVA range on kernel TLB flush To: Jason Gunthorpe , Baolu Lu Cc: Dave Hansen , Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Jann Horn , Vasant Hegde , Alistair Popple , Peter Zijlstra , Uladzislau Rezki , Jean-Philippe Brucker , Andy Lutomirski , Yi Lai , iommu@lists.linux.dev, security@kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20250806052505.3113108-1-baolu.lu@linux.intel.com> <20250806155223.GV184255@nvidia.com> <20250806160904.GX184255@nvidia.com> <62d21545-9e75-41e3-89a3-f21dda15bf16@intel.com> <4a8df0e8-bd5a-44e4-acce-46ba75594846@linux.intel.com> <4ce79c80-1fc8-4684-920a-c8d82c4c3dc8@intel.com> <20250811125753.GT184255@nvidia.com> Content-Language: en-US From: Ethan Zhao In-Reply-To: <20250811125753.GT184255@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/11/2025 8:57 PM, Jason Gunthorpe wrote: > 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() Yep，using guard(spinlock)() for scope-bound lock management sacrifices fine-grained control over the protected area. If offers convenience at the cost of precision. Out of my bias, calling it sluggard(spinlock)() might be proper. Thanks， Ethan > > Jason >