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When we do an FLR, or D0->D3_hot we may lose the BARs as the
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device has turned itself off (and on). This means the device cannot
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function unless the pci_restore_state is called - which it is
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when the PCI device is unbound from the Xen PCI backend driver.
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For PV guests it ends up calling pci_enable_device / pci_enable_msi[x]
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which does the proper steps
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That however is not happening if a HVM guest is run as QEMU
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deals with PCI configuration space. QEMU also requires that the
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device be "parked" under the ownership of a pci-stub driver to
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guarantee that the PCI device is not being used. Hence we
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follow the same incantation as pci_reset_function does - by
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doing an FLR, then restoring the PCI configuration space.
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The result of this patch is that when you run lspci, you get
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now this:
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- Region 0: [virtual] Memory at fe8c0000 (32-bit, non-prefetchable) [size=128K]
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- Region 1: [virtual] Memory at fe800000 (32-bit, non-prefetchable) [size=512K]
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+ Region 0: Memory at fe8c0000 (32-bit, non-prefetchable) [size=128K]
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+ Region 1: Memory at fe800000 (32-bit, non-prefetchable) [size=512K]
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Region 2: I/O ports at c000 [size=32]
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- Region 3: [virtual] Memory at fe8e0000 (32-bit, non-prefetchable) [size=16K]
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+ Region 3: Memory at fe8e0000 (32-bit, non-prefetchable) [size=16K]
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The [virtual] means that lspci read those entries from SysFS but when
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it read them from the device it got a different value (0xfffffff).
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CC: stable@vger.kernel.org # only for v3.4 and v3.5
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Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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---
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drivers/xen/xen-pciback/pci_stub.c | 1 +
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1 files changed, 1 insertions(+), 0 deletions(-)
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diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
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index acec6fa..e5a0c13 100644
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--- a/drivers/xen/xen-pciback/pci_stub.c
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+++ b/drivers/xen/xen-pciback/pci_stub.c
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@@ -362,6 +362,7 @@ static int __devinit pcistub_init_device(struct pci_dev *dev)
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else {
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dev_dbg(&dev->dev, "reseting (FLR, D3, etc) the device\n");
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__pci_reset_function_locked(dev);
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+ pci_restore_state(dev);
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}
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/* Now disable the device (this also ensures some private device
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* data is setup before we export)
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--
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1.7.7.6
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--
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To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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the body of a message to majordomo@vger.kernel.org
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More majordomo info at http://vger.kernel.org/majordomo-info.html
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Please read the FAQ at http://www.tux.org/lkml/
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