From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33361) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XRd3X-0003lD-Ar for qemu-devel@nongnu.org; Wed, 10 Sep 2014 04:15:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XRd3P-0004YW-CD for qemu-devel@nongnu.org; Wed, 10 Sep 2014 04:15:11 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:52962) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XRd3O-0004P4-P2 for qemu-devel@nongnu.org; Wed, 10 Sep 2014 04:15:03 -0400 Received: from /spool/local by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 10 Sep 2014 18:14:57 +1000 From: Nikunj A Dadhania In-Reply-To: <20140910003532.22d72602@bahia.local> References: <1410192283-4026-1-git-send-email-mst@redhat.com> <20140910003532.22d72602@bahia.local> Date: Wed, 10 Sep 2014 13:44:49 +0530 Message-ID: <87oaunops6.fsf@abhimanyu.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH] virtio-pci: enable bus master for old guests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz , "Michael S. Tsirkin" Cc: Alexey Kardashevskiy , Jan Kiszka , qemu-devel@nongnu.org, Anthony Liguori , qemu-stable@nongnu.org Greg Kurz writes: > On Mon, 8 Sep 2014 19:05:02 +0300 > "Michael S. Tsirkin" wrote: > >> commit cc943c36faa192cd4b32af8fe5edb31894017d35 >> pci: Use bus master address space for delivering MSI/MSI-X messages >> breaks virtio-net for rhel6.[56] x86 guests because they don't >> enable bus mastering for virtio PCI devices >> >> Old guests forgot to enable bus mastering, enable it >> automatically on DRIVER_OK. >> >> Note: we should either back out the original patch from >> stable or apply this one on top. >> >> Cc: qemu-stable@nongnu.org >> Reported-by: Greg Kurz >> Signed-off-by: Jan Kiszka >> Signed-off-by: Michael S. Tsirkin >> --- >> hw/virtio/virtio-pci.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c >> index ddb5da1..af937d2 100644 >> --- a/hw/virtio/virtio-pci.c >> +++ b/hw/virtio/virtio-pci.c >> @@ -320,6 +320,8 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) >> if ((val & VIRTIO_CONFIG_S_DRIVER_OK) && >> !(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { >> proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG; >> + memory_region_set_enabled(&proxy->pci_dev.bus_master_enable_region, >> + true); >> } >> break; >> case VIRTIO_MSI_CONFIG_VECTOR: > > Cc'ing Alexey for some SLOF and early boot of the ppc64 kernel expertise. > > Michael, > > This was enough to fix virtio-net in the rhel6.5 x86 guest case. Unfortunately, > this fails for rhel6.5 ppc64 because it is never called... > I did some debugging: it looks like the guest kernel calls the OF > quisece call to flush pending DMA and disables bus master on the > virtio-blk device (PCI_COMMAND == 0x3). Getting confused, above you are talking about virtio-net and here it is virtio-blk. Anyways, the routines still remains same for both of them. From SLOF during init we set DRIVER_OK, and after using the device during the quiesce, called from linux kernel VIRTIO_CONFIG_S_FAILED is set and then a VIRTIO_DEVICE_RESET is done. > The guest then continues to boot and hangs... It appears that waiting > for the guest to issue VIRTIO_CONFIG_S_DRIVER_OK is not enough. Since > we need this for MSI to work, I tried the following and it fixes the > issue: > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index af937d2..3d72aa8 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -111,9 +111,14 @@ static void virtio_pci_notify(DeviceState *d, uint16_t vector) > { > VirtIOPCIProxy *proxy = to_virtio_pci_proxy_fast(d); > > - if (msix_enabled(&proxy->pci_dev)) > + if (msix_enabled(&proxy->pci_dev)) { > + if (!(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { > + proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG; > + memory_region_set_enabled(&proxy->pci_dev.bus_master_enable_region, > + true); > + } > msix_notify(&proxy->pci_dev, vector); > - else { > + } else { > VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); > pci_set_irq(&proxy->pci_dev, vdev->isr & 1); > } > > If this is acceptable, I'll make it a helper and squash it into your patch. > > Thoughts ? > > -- > Gregory Kurz kurzgreg@fr.ibm.com > gkurz@linux.vnet.ibm.com > Software Engineer @ IBM/Meiosys http://www.ibm.com > Tel +33 (0)562 165 496 > > "Anarchy is about taking complete responsibility for yourself." > Alan Moore.