Michael S. Tsirkin
2010-Jun-10 15:22 UTC
[PATCH for-2.6.35] virtio-pci: disable msi at startup
virtio-pci resets the device at startup by writing to the status
register, but this does not clear the pci config space,
specifically msi enable status which affects register
layout.
This breaks things like kdump when they try to use e.g. virtio-blk.
Fix by forcing msi off at startup. Since pci.c already has
a routine to do this, we export and use it instead of duplicating code.
Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
Tested-by: Vivek Goyal <vgoyal at redhat.com>
Cc: Jesse Barnes <jbarnes at virtuousgeek.org>
Cc: linux-pci at vger.kernel.org
---
Jesse, could you ack adding the pci export please?
Rusty, please consider this patch for 2.6.35.
drivers/pci/pci.c | 1 +
drivers/virtio/virtio_pci.c | 3 +++
include/linux/pci.h | 4 ++++
3 files changed, 8 insertions(+), 0 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 60f30e7..740fb4e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2292,6 +2292,7 @@ void pci_msi_off(struct pci_dev *dev)
pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);
}
}
+EXPORT_SYMBOL_GPL(pci_msi_off);
#ifndef HAVE_ARCH_PCI_SET_DMA_MAX_SEGMENT_SIZE
int pci_set_dma_max_seg_size(struct pci_dev *dev, unsigned int size)
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 95896f3..ef8d9d5 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -636,6 +636,9 @@ static int __devinit virtio_pci_probe(struct pci_dev
*pci_dev,
INIT_LIST_HEAD(&vp_dev->virtqueues);
spin_lock_init(&vp_dev->lock);
+ /* Disable MSI/MSIX to bring device to a known good state. */
+ pci_msi_off(pci_dev);
+
/* enable the device */
err = pci_enable_device(pci_dev);
if (err)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 7cb0084..31d8a12 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -780,7 +780,11 @@ int __must_check pci_set_mwi(struct pci_dev *dev);
int pci_try_set_mwi(struct pci_dev *dev);
void pci_clear_mwi(struct pci_dev *dev);
void pci_intx(struct pci_dev *dev, int enable);
+#ifdef CONFIG_PCI_MSI
void pci_msi_off(struct pci_dev *dev);
+#else
+static inline void pci_msi_off(struct pci_dev *dev) {}
+#endif
int pci_set_dma_max_seg_size(struct pci_dev *dev, unsigned int size);
int pci_set_dma_seg_boundary(struct pci_dev *dev, unsigned long mask);
int pcix_get_max_mmrbc(struct pci_dev *dev);
--
1.7.1.12.g42b7f
On Thu, 10 Jun 2010 18:22:52 +0300 "Michael S. Tsirkin" <mst at redhat.com> wrote:> virtio-pci resets the device at startup by writing to the status > register, but this does not clear the pci config space, > specifically msi enable status which affects register > layout. > > This breaks things like kdump when they try to use e.g. virtio-blk. > > Fix by forcing msi off at startup. Since pci.c already has > a routine to do this, we export and use it instead of duplicating code. > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > Tested-by: Vivek Goyal <vgoyal at redhat.com> > Cc: Jesse Barnes <jbarnes at virtuousgeek.org> > Cc: linux-pci at vger.kernel.org > ---Yeah, looks fine. Acked-by: Jesse Barnes <jbarnes at virtuousgeek.org> -- Jesse Barnes, Intel Open Source Technology Center
On 06/10/2010 06:22 PM, Michael S. Tsirkin wrote:> virtio-pci resets the device at startup by writing to the status > register, but this does not clear the pci config space, > specifically msi enable status which affects register > layout. > > This breaks things like kdump when they try to use e.g. virtio-blk. > > Fix by forcing msi off at startup. Since pci.c already has > a routine to do this, we export and use it instead of duplicating code. > >Why doesn't a device reset result in msi being cleared? Shouldn't a reset be equivalent to power cycling? -- error compiling committee.c: too many arguments to function