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Tsirkin" To: Gerd Hoffmann Cc: Sean Christopherson , Vitaly Kuznetsov , Peter Xu , kvm@vger.kernel.org, Paolo Bonzini , Wanpeng Li , Jim Mattson , Julia Suvorova , Andy Lutomirski , Andrew Jones , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/3] KVM: x86: KVM_MEM_PCI_HOLE memory Message-ID: <20200907065054-mutt-send-email-mst@kernel.org> References: <20200807141232.402895-1-vkuznets@redhat.com> <20200825212526.GC8235@xz-x1> <87eenlwoaa.fsf@vitty.brq.redhat.com> <20200901200021.GB3053@xz-x1> <877dtcpn9z.fsf@vitty.brq.redhat.com> <20200904061210.GA22435@sjchrist-ice> <20200904072905.vbkiq3h762fyzds6@sirius.home.kraxel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200904072905.vbkiq3h762fyzds6@sirius.home.kraxel.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Sep 04, 2020 at 09:29:05AM +0200, Gerd Hoffmann wrote: > Hi, > > > Unless I'm mistaken, microvm doesn't even support PCI, does it? > > Correct, no pci support right now. > > We could probably wire up ecam (arm/virt style) for pcie support, once > the acpi support for mictovm finally landed (we need acpi for that > because otherwise the kernel wouldn't find the pcie bus). > > Question is whenever there is a good reason to do so. Why would someone > prefer microvm with pcie support over q35? The usual reasons to use pcie apply to microvm just the same. E.g.: pass through of pcie devices? > > If all of the above is true, this can be handled by adding "pci=lastbus=0" > > as a guest kernel param to override its scanning of buses. And couldn't > > that be done by QEMU's microvm_fix_kernel_cmdline() to make it transparent > > to the end user? > > microvm_fix_kernel_cmdline() is a hack, not a solution. > > Beside that I doubt this has much of an effect on microvm because > it doesn't support pcie in the first place. > > take care, > Gerd