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Wed, 25 Feb 2026 16:30:02 +0000 From: Date: Wed, 25 Feb 2026 08:30:00 -0800 To: Alexey Kardashevskiy , CC: , , , Thomas Gleixner , "Ingo Molnar" , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , "Sean Christopherson" , Paolo Bonzini , "Andy Lutomirski" , Peter Zijlstra , "Bjorn Helgaas" , Dan Williams , "Marek Szyprowski" , Robin Murphy , Andrew Morton , Catalin Marinas , Michael Ellerman , "Mike Rapoport" , Tom Lendacky , "Ard Biesheuvel" , Neeraj Upadhyay , Ashish Kalra , Stefano Garzarella , Melody Wang , Seongman Lee , Joerg Roedel , "Nikunj A Dadhania" , Michael Roth , "Suravee Suthikulpanit" , Andi Kleen , Kuppuswamy Sathyanarayanan , Tony Luck , David Woodhouse , "Greg Kroah-Hartman" , Denis Efremov , Geliang Tang , Piotr Gregor , "Michael S. Tsirkin" , "Alex Williamson" , Arnd Bergmann , Jesse Barnes , Jacob Pan , Yinghai Lu , Kevin Brodsky , Jonathan Cameron , "Aneesh Kumar K.V (Arm)" , Xu Yilun , Herbert Xu , Kim Phillips , "Konrad Rzeszutek Wilk" , Stefano Stabellini , Claire Chang , , , Alexey Kardashevskiy Message-ID: <699f238873ae7_1cc5100b6@dwillia2-mobl4.notmuch> In-Reply-To: <20260225053806.3311234-5-aik@amd.com> References: <20260225053806.3311234-1-aik@amd.com> <20260225053806.3311234-5-aik@amd.com> Subject: Re: [PATCH kernel 4/9] dma/swiotlb: Stop forcing SWIOTLB for TDISP devices Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SJ0PR05CA0086.namprd05.prod.outlook.com (2603:10b6:a03:332::31) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR11MB8107:EE_|DS7PR11MB6176:EE_ X-MS-Office365-Filtering-Correlation-Id: 219a5298-2cb9-445e-9852-08de748b202b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|7416014|1800799024|7053199007; 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> > + /* > + * CC_ATTR_GUEST_MEM_ENCRYPT enforces SWIOTLB_FORCE in > + * swiotlb_init_remap() to allow legacy devices access arbitrary > + * VM encrypted memory. > + * Skip it for TDISP devices capable of DMA-ing the encrypted memory. > + */ > + if (device_cc_accepted(dev)) > + return false; I worry this further muddies the meaning of the swiotlb force option. What if you want to force swiotlb operation on accepted devices? For example: @@ -173,7 +176,13 @@ static inline bool is_swiotlb_force_bounce(struct device *dev) { struct io_tlb_mem *mem = dev->dma_io_tlb_mem; - return mem && mem->force_bounce; + if (!mem) + return false; + if (mem->force_bounce) + return true; + if (mem->bounce_unaccepted && !device_cc_accepted(dev)) + return true; + return false; } void swiotlb_init(bool addressing_limited, unsigned int flags);