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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id af79cd13be357-93ef5086fe3sm818646485a.37.2026.10.15.10.37.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Oct 2026 10:37:08 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xHPO7-0000000H6B3-44RG; Thu, 15 Oct 2026 14:37:07 -0300 Date: Thu, 15 Oct 2026 14:37:07 -0300 From: Jason Gunthorpe To: Xu Yilun Cc: Lu Baolu , iommu@lists.linux.dev, x86@kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, Kevin Tian , Kiryl Shutsemau , Rick Edgecombe , xiaoyao.li@intel.com, Chao Gao , Binbin Wu , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 4/4] coco/tdx-host: Initialize trusted DMA on all capable IOMMUs Message-ID: <20261015173707.GV14213@ziepe.ca> References: <20261015010705.1973284-1-baolu.lu@linux.intel.com> <20261015010705.1973284-5-baolu.lu@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Oct 15, 2026 at 04:31:31PM +0800, Xu Yilun wrote: > An alternative could be, bringing up one IOMMU when an associated > device requests link encryption. Then a no-tdx-support iommu fails the > encryption request naturally. That is what ARM is planning to do. I think it is reasonable to trigger creation of the secure iommu when the TSM is connected to TDX. Fail connect if the iommu could not be created. Jason