From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:52719) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ehKqn-0000cf-BG for qemu-devel@nongnu.org; Thu, 01 Feb 2018 14:49:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ehKhE-0004QM-3n for qemu-devel@nongnu.org; Thu, 01 Feb 2018 14:43:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44434) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ehKhD-0004Pi-NW for qemu-devel@nongnu.org; Thu, 01 Feb 2018 14:38:55 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E48334E4D0 for ; Thu, 1 Feb 2018 19:38:54 +0000 (UTC) Date: Thu, 1 Feb 2018 19:38:38 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20180201193838.GM2457@work-vm> References: <20180201112028.23552-1-peterx@redhat.com> <90b4bc63-94cd-ec0f-32c8-c16df8ee84cf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <90b4bc63-94cd-ec0f-32c8-c16df8ee84cf@redhat.com> Subject: Re: [Qemu-devel] [PATCH] pcie-root-port: let it has higher migrate priority List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcel Apfelbaum Cc: Peter Xu , qemu-devel@nongnu.org, Alex Williamson , "Michael S . Tsirkin" , Juan Quintela , Laurent Vivier * Marcel Apfelbaum (marcel@redhat.com) wrote: > Hi Peter, > > On 01/02/2018 13:20, Peter Xu wrote: > > In the past, we prioritized IOMMU migration so that we have such a > > priority order: > > > > IOMMU > PCI Devices > > > > When migrating a guest with both vIOMMU and pcie-root-port, we'll always > > migrate vIOMMU first, since pcie-root-port will be seen to have the same > > priority of general PCI devices. > > > > That's problematic. > > > > The thing is that PCI bus number information is stored in the root port, > > and that is needed by vIOMMU during post_load(), e.g., to figure out > > context entry for a device. If we don't have correct bus numbers for > > devices, we won't be able to recover device state of the DMAR memory > > regions, and things will be messed up. > > > > So let's boost the PCIe root ports to be even with higher priority: > > > > PCIe Root Port > IOMMU > PCI Devices > > > > A smoke test shows that this patch fixes bug 1538953. > > > > CC: Alex Williamson > > CC: Marcel Apfelbaum > > CC: Michael S. Tsirkin > > CC: Dr. David Alan Gilbert > > CC: Juan Quintela > > CC: Laurent Vivier > > Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1538953 > > Reported-by: Maxime Coquelin > > Signed-off-by: Peter Xu > > --- > > Marcel & all, > > > > I think it's possible that we need similar thing for other bridge-like > > devices, but I'm not that familiar. Would you help confirm? Thanks, > > Is a pity we don't have a way to mark the migration priority > in a base class. Dave, maybe we do have a way? Not that I'm aware of; the 'priority' field is associated with the VMSD and it's not really connected to the class hierarchy at all. Dave > In the meantime you would need to add it also to: > - ioh3420 (Intel root port) > - xio3130_downstream (Intel switch downstream port) > - xio3130_upstream (The counterpart of the above, you want the whole > switch to be migrated before loading the IOMMU device state) > - pcie_pci_bridge (for pci devices) > - pci-pci bridge (if for some reason you have one attached to the pcie_pci_brdge) > - i82801b11 (dmi-pci bridge, we want to deprecate it bu is there for now) > > Thanks, > Marcel > > > hw/pci-bridge/gen_pcie_root_port.c | 1 + > > include/migration/vmstate.h | 1 + > > 2 files changed, 2 insertions(+) > > > > diff --git a/hw/pci-bridge/gen_pcie_root_port.c b/hw/pci-bridge/gen_pcie_root_port.c > > index 0e2f2e8bf1..e6ff1effd8 100644 > > --- a/hw/pci-bridge/gen_pcie_root_port.c > > +++ b/hw/pci-bridge/gen_pcie_root_port.c > > @@ -101,6 +101,7 @@ static void gen_rp_realize(DeviceState *dev, Error **errp) > > > > static const VMStateDescription vmstate_rp_dev = { > > .name = "pcie-root-port", > > + .priority = MIG_PRI_PCIE_ROOT_PORT, > > .version_id = 1, > > .minimum_version_id = 1, > > .post_load = pcie_cap_slot_post_load, > > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h > > index 8c3889433c..491449db9f 100644 > > --- a/include/migration/vmstate.h > > +++ b/include/migration/vmstate.h > > @@ -148,6 +148,7 @@ enum VMStateFlags { > > typedef enum { > > MIG_PRI_DEFAULT = 0, > > MIG_PRI_IOMMU, /* Must happen before PCI devices */ > > + MIG_PRI_PCIE_ROOT_PORT, /* Must happen before IOMMU */ > > MIG_PRI_GICV3_ITS, /* Must happen before PCI devices */ > > MIG_PRI_GICV3, /* Must happen before the ITS */ > > MIG_PRI_MAX, > > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK