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xen/pciback: Restore the PCI config space after an FLR.
When we do an FLR, or D0->D3_hot we may lose the BARs as the device has turned itself off (and on). This means the device cannot function unless the pci_restore_state is called - which it is when the PCI device is unbound from the Xen PCI backend driver. For PV guests it ends up calling pci_enable_device / pci_enable_msi[x] which does the proper steps That however is not happening if a HVM guest is run as QEMU deals with PCI configuration space. QEMU also requires that the device be "parked" under the ownership of a pci-stub driver to guarantee that the PCI device is not being used. Hence we follow the same incantation as pci_reset_function does - by doing an FLR, then restoring the PCI configuration space. The result of this patch is that when you run lspci, you get now this: - Region 0: [virtual] Memory at fe8c0000 (32-bit, non-prefetchable) [size=128K] - Region 1: [virtual] Memory at fe800000 (32-bit, non-prefetchable) [size=512K] + Region 0: Memory at fe8c0000 (32-bit, non-prefetchable) [size=128K] + Region 1: Memory at fe800000 (32-bit, non-prefetchable) [size=512K] Region 2: I/O ports at c000 [size=32] - Region 3: [virtual] Memory at fe8e0000 (32-bit, non-prefetchable) [size=16K] + Region 3: Memory at fe8e0000 (32-bit, non-prefetchable) [size=16K] The [virtual] means that lspci read those entries from SysFS but when it read them from the device it got a different value (0xfffffff). CC: stable@vger.kernel.org #only for 3.5, 3.6 Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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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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