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[47.55.122.23]) by smtp.gmail.com with ESMTPSA id ca6-20020a05622a1f0600b003994bbe91bdsm7900801qtb.60.2022.10.12.06.02.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Oct 2022 06:02:31 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1oibNV-001wVQ-HJ; Wed, 12 Oct 2022 10:02:29 -0300 Date: Wed, 12 Oct 2022 10:02:29 -0300 From: Jason Gunthorpe To: "Radovanovic, Aleksandar" Cc: "Gupta, Nipun" , Marc Zyngier , Robin Murphy , "robh+dt@kernel.org" , "krzysztof.kozlowski+dt@linaro.org" , "gregkh@linuxfoundation.org" , "rafael@kernel.org" , "eric.auger@redhat.com" , "alex.williamson@redhat.com" , "cohuck@redhat.com" , "Gupta, Puneet (DCG-ENG)" , "song.bao.hua@hisilicon.com" , "mchehab+huawei@kernel.org" , "f.fainelli@gmail.com" , "jeffrey.l.hugo@gmail.com" , "saravanak@google.com" , "Michael.Srba@seznam.cz" , "mani@kernel.org" , "yishaih@nvidia.com" , "will@kernel.org" , "joro@8bytes.org" , "masahiroy@kernel.org" , "ndesaulniers@google.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kbuild@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , "kvm@vger.kernel.org" , "okaya@kernel.org" , "Anand, Harpreet" , "Agarwal, Nikhil" , "Simek, Michal" , "git (AMD-Xilinx)" Subject: Re: [RFC PATCH v3 4/7] bus/cdx: add cdx-MSI domain with gic-its domain as parent Message-ID: References: <20220803122655.100254-1-nipun.gupta@amd.com> <20220906134801.4079497-1-nipun.gupta@amd.com> <20220906134801.4079497-5-nipun.gupta@amd.com> <87h71juxuk.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221012_060247_214888_E653DFC9 X-CRM114-Status: GOOD ( 14.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 12, 2022 at 10:34:23AM +0000, Radovanovic, Aleksandar wrote: > For the MSI EventID, the HW interrupt logic assumes the MSI write value is > equal to the MSI vector number. However, the vector number is programmable > for most (all) of the interrupt sources, which isn't exactly the same as saying > EventID is programmable for a vector number, but can be used to emulate the > desired behaviour, with a translation table in firmware. If you do this stuff wrong you will eventually run into situations that don't work. Like VFIO/VMs and things. > As for GITS_TRANSLATER, we can take up to 4 different IOVAs, which limits us > to 4 CDX devices (should be sufficient for current HW use-cases). Also, it means > that the address part must be the same for all vectors within a single CDX > device. I'm assuming this is OK as it is going to be a single interrupt and IOMMU > domain anyway. This is not at all how MSI is supposed to work. Jason _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel