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([2001:b07:6468:f312:bdd8:ac77:1ff4:62c6]) by smtp.gmail.com with ESMTPSA id y3sm266623wrt.87.2020.05.14.14.17.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 May 2020 14:17:30 -0700 (PDT) Subject: Re: [RFC PATCH] KVM: Add module for IRQ forwarding To: Micah Morton , Auger Eric Cc: Alex Williamson , kvm@vger.kernel.org, jmattson@google.com References: <20200511220046.120206-1-mortonm@chromium.org> <20200512111440.15caaca2@w520.home> <92fd66eb-68e7-596f-7dd1-f1c190833be4@redhat.com> <20200513083401.11e761a7@x1.home> <8c0bfeb7-0d08-db74-3a23-7a850f301a2a@redhat.com> <0fdb5d54-e4d6-8f2f-69fe-1b157999d6cd@redhat.com> From: Paolo Bonzini Message-ID: <9d5d7eec-77dd-bca9-949f-8f39fcd7d8d7@redhat.com> Date: Thu, 14 May 2020 23:17:29 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 14/05/20 19:44, Micah Morton wrote: > I realize this may seem like an over-use of VFIO, but I'm actually > coming from the angle of wanting to assign _most_ of the important > hardware on my device to a VM guest, and I'm looking to avoid > emulation wherever possible. Of course there will be devices like the > IOAPIC for which emulation is unavoidable, but I think emulation is > avoidable here for the busses we've mentioned if there is a way to > forward arbitrary interrupts into the guest. > > Since all these use cases are so close to working with vfio-pci right > out of the box, I was really hoping to come up with a simple and > generic solution to the arbitrary interrupt problem that can be used > for multiple bus types. I shall defer to Alex on this, but I think the main issue here is that these interrupts are not visible to Linux as pertaining to the pci-stub device. Is this correct? Paolo