From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53827) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XRXoe-0007z9-J2 for qemu-devel@nongnu.org; Tue, 09 Sep 2014 22:39:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XRXoY-00061F-4h for qemu-devel@nongnu.org; Tue, 09 Sep 2014 22:39:28 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:50798) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XRXoX-00060p-TM for qemu-devel@nongnu.org; Tue, 09 Sep 2014 22:39:22 -0400 Received: by mail-pa0-f50.google.com with SMTP id bj1so4773090pad.9 for ; Tue, 09 Sep 2014 19:39:21 -0700 (PDT) Message-ID: <540FB9CF.6020303@ozlabs.ru> Date: Wed, 10 Sep 2014 12:39:11 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <1410192283-4026-1-git-send-email-mst@redhat.com> <20140910003532.22d72602@bahia.local> In-Reply-To: <20140910003532.22d72602@bahia.local> Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit 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: Jan Kiszka , Nikunj A Dadhania , qemu-devel@nongnu.org, Anthony Liguori , qemu-stable@nongnu.org On 09/10/2014 08:35 AM, Greg Kurz wrote: > 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. Cc'ing Nikunj - he is SLOF expert. I cannot comment - I have no idea what VIRTIO_PCI_FLAG_BUS_MASTER_BUG does. > > 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). 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 ? > -- Alexey