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Tsirkin" To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Subject: Re: [PULL 1/5] hw/pcie-root-port: Fix hotplug for PCI devices requiring IO Message-ID: <20210927053932-mutt-send-email-mst@kernel.org> References: <20210803205043.165034-1-mst@redhat.com> <20210803205043.165034-2-mst@redhat.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marcel Apfelbaum , Peter Maydell , qemu-devel@nongnu.org, Igor Mammedov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Sep 27, 2021 at 10:33:42AM +0100, Daniel P. Berrangé wrote: > On Tue, Aug 03, 2021 at 04:52:03PM -0400, Michael S. Tsirkin wrote: > > From: Marcel Apfelbaum > > > > Q35 has now ACPI hotplug enabled by default for PCI(e) devices. > > As opposed to native PCIe hotplug, guests like Fedora 34 > > will not assign IO range to pcie-root-ports not supporting > > native hotplug, resulting into a regression. > > > > Reproduce by: > > qemu-bin -M q35 -device pcie-root-port,id=p1 -monitor stdio > > device_add e1000,bus=p1 > > In the Guest OS the respective pcie-root-port will have the IO range > > disabled. > > > > Fix it by setting the "reserve-io" hint capability of the > > pcie-root-ports so the firmware will allocate the IO range instead. > > > > Acked-by: Igor Mammedov > > Signed-off-by: Marcel Apfelbaum > > Message-Id: <20210802090057.1709775-1-marcel@redhat.com> > > Reviewed-by: Michael S. Tsirkin > > Signed-off-by: Michael S. Tsirkin > > --- > > hw/pci-bridge/gen_pcie_root_port.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > This change, when combined with the switch to ACPI based hotplug by > default, is responsible for a significant regression in QEMU 6.1.0 > > It is no longer possible to have more than 15 pcie-root-port devices > added to a q35 VM in 6.1.0. Before this I've had as many as 80+ devices > present before I stopped trying to add more. > > https://gitlab.com/qemu-project/qemu/-/issues/641 > > This regression is significant, because it has broken the out of the > box default configuration that OpenStack uses for booting all VMs. > They add 16 pcie-root-ports by defalt to allow empty slots for device > hotplug under q35 [1]. Indeed, oops. Thanks for the report! Going back and looking at seabios code, didn't we get confused? Shouldn't we have reserved memory and not IO? I see: int resource_optional = pcie_cap && (type == PCI_REGION_TYPE_IO); if (!sum && hotplug_support && !resource_optional) sum = align; /* reserve min size for hot-plug */ generally maybe we should just add an ACPI-hotplug capability and teach seabios about it? Marcel? > > diff --git a/hw/pci-bridge/gen_pcie_root_port.c b/hw/pci-bridge/gen_pcie_root_port.c > > index ec9907917e..20099a8ae3 100644 > > --- a/hw/pci-bridge/gen_pcie_root_port.c > > +++ b/hw/pci-bridge/gen_pcie_root_port.c > > @@ -28,6 +28,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(GenPCIERootPort, GEN_PCIE_ROOT_PORT) > > (GEN_PCIE_ROOT_PORT_AER_OFFSET + PCI_ERR_SIZEOF) > > > > #define GEN_PCIE_ROOT_PORT_MSIX_NR_VECTOR 1 > > +#define GEN_PCIE_ROOT_DEFAULT_IO_RANGE 4096 > > > > struct GenPCIERootPort { > > /*< private >*/ > > @@ -75,6 +76,7 @@ static bool gen_rp_test_migrate_msix(void *opaque, int version_id) > > static void gen_rp_realize(DeviceState *dev, Error **errp) > > { > > PCIDevice *d = PCI_DEVICE(dev); > > + PCIESlot *s = PCIE_SLOT(d); > > GenPCIERootPort *grp = GEN_PCIE_ROOT_PORT(d); > > PCIERootPortClass *rpc = PCIE_ROOT_PORT_GET_CLASS(d); > > Error *local_err = NULL; > > @@ -85,6 +87,9 @@ static void gen_rp_realize(DeviceState *dev, Error **errp) > > return; > > } > > > > + if (grp->res_reserve.io == -1 && s->hotplug && !s->native_hotplug) { > > + grp->res_reserve.io = GEN_PCIE_ROOT_DEFAULT_IO_RANGE; > > + } > > int rc = pci_bridge_qemu_reserve_cap_init(d, 0, > > grp->res_reserve, errp); > > > > -- > > MST > > > > > > Regards, > Daniel > > [1] https://github.com/openstack/tripleo-heat-templates/blob/7a6cd0640ec390a330f5699d8ed60f71b2a9f514/deployment/nova/nova-compute-container-puppet.yaml#L462-L472 > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|