From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35689) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XRdBV-0000TC-Po for qemu-devel@nongnu.org; Wed, 10 Sep 2014 04:23:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XRdBR-0007i2-1l for qemu-devel@nongnu.org; Wed, 10 Sep 2014 04:23:25 -0400 Date: Wed, 10 Sep 2014 12:26:37 +0300 From: "Michael S. Tsirkin" Message-ID: <20140910092637.GA7902@redhat.com> References: <1410192283-4026-1-git-send-email-mst@redhat.com> <20140910003532.22d72602@bahia.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140910003532.22d72602@bahia.local> 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 Cc: Alexey Kardashevskiy , Jan Kiszka , qemu-devel@nongnu.org, Anthony Liguori , qemu-stable@nongnu.org On Wed, Sep 10, 2014 at 12:35:32AM +0200, 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. > > 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. Got it. Writing to PCI_COMMAND disabled bus mastering again. This should do it, on top - can you confirm please? diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index af937d2..6b7ac39 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -475,10 +475,14 @@ 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)) { - virtio_pci_stop_ioeventfd(proxy); - virtio_set_status(vdev, vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK); + !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { + if (proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG) { + memory_region_set_enabled(&proxy->pci_dev.bus_master_enable_region, + true); + } else { + virtio_pci_stop_ioeventfd(proxy); + virtio_set_status(vdev, vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK); + } } }