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[142.167.56.70]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7d3b8eaca05sm705183585a.73.2025.06.17.16.03.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Jun 2025 16:03:34 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1uRfL4-00000006eJX-07UY; Tue, 17 Jun 2025 20:03:34 -0300 Date: Tue, 17 Jun 2025 20:03:34 -0300 From: Jason Gunthorpe To: "Michael S. Tsirkin" Subject: Re: Virtio-IOMMU interrupt remapping design Message-ID: <20250617230334.GJ1376515@ziepe.ca> References: <> <20250616132031.GB1354058@ziepe.ca> <20250617154331-mutt-send-email-mst@kernel.org> <20250617195720.GI1376515@ziepe.ca> <20250617160103-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250617160103-mutt-send-email-mst@kernel.org> Message-ID-Hash: FOZZU573BHF2LQNOGOLQJBDQCFQULB7V X-Message-ID-Hash: FOZZU573BHF2LQNOGOLQJBDQCFQULB7V X-MailFrom: jgg@ziepe.ca X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-devel.spectrum-os.org-0; header-match-devel.spectrum-os.org-1; header-match-devel.spectrum-os.org-2; header-match-devel.spectrum-os.org-3; header-match-devel.spectrum-os.org-4; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Demi Marie Obenour , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , "Rafael J. Wysocki" , Len Brown , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Joerg Roedel , Will Deacon , Robin Murphy , Alyssa Ross , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, iommu@lists.linux.dev, x86@kernel.org, Spectrum OS Development X-Mailman-Version: 3.3.9 Precedence: list List-Id: Patches and low-level development discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Tue, Jun 17, 2025 at 04:01:53PM -0400, Michael S. Tsirkin wrote: > > On x86 you also need to use remapping to exceed the max CPU count that > > can be encoded in the MSI, no iommu required to need this. > > More of an x86 quirk though, isn't it? Yes, but so is bundling IOMMU and remapping HW together GIC fully integrates it into the interrupt controller architecture. Jason