From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40400) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XdbRv-0008Eo-2G for qemu-devel@nongnu.org; Mon, 13 Oct 2014 04:57:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XdbRn-0004Rw-W3 for qemu-devel@nongnu.org; Mon, 13 Oct 2014 04:57:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:14060) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XdbRn-0004Rg-Nq for qemu-devel@nongnu.org; Mon, 13 Oct 2014 04:57:43 -0400 Date: Mon, 13 Oct 2014 12:01:07 +0300 From: "Michael S. Tsirkin" Message-ID: <20141013090107.GA12539@redhat.com> References: <1410719415-23769-1-git-send-email-mst@redhat.com> <20140917192109.5ee87811@bahia.local> <20140917173925.GA19710@redhat.com> <20141006165135.5e158064@bahia.local> <20141006162621.GA2633@redhat.com> <20141006184617.37a2d886@bahia.local> <20141006172504.GA7084@redhat.com> <20141013104941.78c8b13e@bahia.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141013104941.78c8b13e@bahia.local> Subject: Re: [Qemu-devel] [PATCH] virtio-pci: fix migration for pci bus master List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: Jason Wang , Nikunj A Dadhania , qemu-devel@nongnu.org, Anthony Liguori On Mon, Oct 13, 2014 at 10:49:41AM +0200, Greg Kurz wrote: > On Mon, 6 Oct 2014 20:25:04 +0300 > "Michael S. Tsirkin" wrote: > > [...] > > > > BTW I reverted that patch, and to fix migration, I'm thinking > > about applying the following patch on top of master. > > > > Michael, > > I could force the migration issue with a rhel65 guest thanks to the > following patch, applied to hw/virtio/virtio-pci.c in QEMU v2.1. > > @@ -271,6 +272,16 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) > VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); > hwaddr pa; > > + if ((vdev->status == (VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER)) > + && (!(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) > + && getenv("MIG_BUG")) > + { > + fprintf(stderr, "\n\n\n\tMIGRATE !\n\n\n"); > + qmp_migrate(getenv("MIG_BUG"), false, false, false, false, false, > + false, NULL); > + unsetenv("MIG_BUG"); > + } > + > switch (addr) { > case VIRTIO_PCI_GUEST_FEATURES: > /* Guest does not negotiate properly? We have to assume nothing. */ > > > Indeed, the destination QEMU master hangs because bus master isn't set. > > > Would appreciate testing cross-version migration (2.1 to master) > > with this patch applied. > > > > I had first to to enable the property for pseries of course. I could then > migrate QEMU v2.1 to QEMU master and back to QEMU v2.1, in the window > where we have DRIVER enabled and MASTER disabled, without experiencing > the hang. > > Your fix works as expected (just a remark below). > > > > > > > diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h > > index 1cea157..8873b6d 100644 > > --- a/hw/virtio/virtio-pci.h > > +++ b/hw/virtio/virtio-pci.h > > @@ -53,6 +53,11 @@ typedef struct VirtioBusClass VirtioPCIBusClass; > > #define VIRTIO_PCI_BUS_CLASS(klass) \ > > OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS) > > > > +/* Need to activate work-arounds for buggy guests at vmstate load. */ > > +#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT 0 > > +#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \ > > + (1 << VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT) > > + > > /* Performance improves when virtqueue kick processing is decoupled from the > > * vcpu thread using ioeventfd for some devices. */ > > #define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1 > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h > > index bae023a..e07b6c4 100644 > > --- a/include/hw/i386/pc.h > > +++ b/include/hw/i386/pc.h > > @@ -312,6 +312,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *); > > .driver = "intel-hda",\ > > .property = "old_msi_addr",\ > > .value = "on",\ > > + },\ > > + {\ > > + .driver = "virtio-pci",\ > > + .property = "virtio-pci-bus-master-bug-migration",\ > > + .value = "on",\ > > } > > > > #define PC_COMPAT_2_0 \ > > FWIW, the issue does not occur with intel targets, at least not > in my test case (booting rhel6 on a virtio-blk disk). I see bus > master is set early (bios ?) and never unset... > > If you decide to apply for intel anyway, shouldn't the enablement be > in a separate patch ? > > Will you resend or would you like me to do it, along with the pseries > enablement part ? In this case, I would need your SoB for the present > patch. > > Thanks. > > -- > Greg AFAIK pseries doesn't support cross-version migration, does it? > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > > index a827cd4..a499a3c 100644 > > --- a/hw/virtio/virtio-pci.c > > +++ b/hw/virtio/virtio-pci.c > > @@ -86,9 +86,6 @@ > > * 12 is historical, and due to x86 page size. */ > > #define VIRTIO_PCI_QUEUE_ADDR_SHIFT 12 > > > > -/* Flags track per-device state like workarounds for quirks in older guests. */ > > -#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG (1 << 0) > > - > > static void virtio_pci_bus_new(VirtioBusState *bus, size_t bus_size, > > VirtIOPCIProxy *dev); > > > > @@ -323,14 +320,6 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) > > proxy->pci_dev.config[PCI_COMMAND] | > > PCI_COMMAND_MASTER, 1); > > } > > - > > - /* Linux before 2.6.34 sets the device as OK without enabling > > - the PCI device bus master bit. In this case we need to disable > > - some safety checks. */ > > - if ((val & VIRTIO_CONFIG_S_DRIVER_OK) && > > - !(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { > > - proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG; > > - } > > break; > > case VIRTIO_MSI_CONFIG_VECTOR: > > msix_vector_unuse(&proxy->pci_dev, vdev->config_vector); > > @@ -483,8 +472,7 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address, > > pci_default_write_config(pci_dev, address, val, len); > > > > if (range_covers_byte(address, len, PCI_COMMAND) && > > - !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER) && > > - !(proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG)) { > > + !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { > > virtio_pci_stop_ioeventfd(proxy); > > virtio_set_status(vdev, vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK); > > } > > @@ -895,11 +883,15 @@ static void virtio_pci_vmstate_change(DeviceState *d, bool running) > > VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); > > > > if (running) { > > - /* Try to find out if the guest has bus master disabled, but is > > - in ready state. Then we have a buggy guest OS. */ > > - if ((vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) && > > + /* Old QEMU versions did not set bus master enable on status write. > > + * Detect DRIVER set and enable it. > > + */ > > + if ((proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION) && > > + (vdev->status & VIRTIO_CONFIG_S_DRIVER) && > > !(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { > > - proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG; > > + pci_default_write_config(&proxy->pci_dev, PCI_COMMAND, > > + proxy->pci_dev.config[PCI_COMMAND] | > > + PCI_COMMAND_MASTER, 1); > > } > > virtio_pci_start_ioeventfd(proxy); > > } else { > > @@ -1040,10 +1032,11 @@ static void virtio_pci_reset(DeviceState *qdev) > > virtio_pci_stop_ioeventfd(proxy); > > virtio_bus_reset(bus); > > msix_unuse_all_vectors(&proxy->pci_dev); > > - proxy->flags &= ~VIRTIO_PCI_FLAG_BUS_MASTER_BUG; > > } > > > > static Property virtio_pci_properties[] = { > > + DEFINE_PROP_BIT("virtio-pci-bus-master-bug-migration", VirtIOPCIProxy, flags, > > + VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT, false), > > DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features), > > DEFINE_PROP_END_OF_LIST(), > > }; > >