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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2013-06-10 16:48:09 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-07-21 18:21:27 -0700
commit9ceb896c679bf0fb6c8c968cf006ec8593052f37 (patch)
tree02817d4a1a1cd6dde4d45bc689fbb1768f44ddb4
parentac9349c428f94f636e3ca4d5d92cf048dd819518 (diff)
downloadvexpress-lsk-9ceb896c679bf0fb6c8c968cf006ec8593052f37.tar.gz
xen/pcifront: Deal with toolstack missing 'XenbusStateClosing' state.
commit 098b1aeaf4d6149953b8f1f8d55c21d85536fbff upstream. There are two tool-stack that can instruct the Xen PCI frontend and backend to change states: 'xm' (Python code with a daemon), and 'xl' (C library - does not keep state changes). With the 'xm', the path to disconnect a single PCI device (xm pci-detach <guest> <BDF>) is: 4(Connected)->7(Reconfiguring*)-> 8(Reconfigured)-> 4(Connected)->5(Closing*). The * is for states that the tool-stack sets. For 'xl', it is similar: 4(Connected)->7(Reconfiguring*)-> 8(Reconfigured)-> 4(Connected) Both of them also tear down the XenBus structure, so the backend state ends up going in the 3(Initialised) and calls pcifront_xenbus_remove. When a PCI device is plugged back in (xm pci-attach <guest> <BDF>) both of them follow the same pattern: 2(InitWait*), 3(Initialized*), 4(Connected*)->4(Connected). [xen-pcifront ignores the 2,3 state changes and only acts when 4 (Connected) has been reached] Note that this is for a _single_ PCI device. If there were two PCI devices and only one was disconnected 'xm' would show the same state changes. The problem is that git commit 3d925320e9e2de162bd138bf97816bda8c3f71be ("xen/pcifront: Use Xen-SWIOTLB when initting if required") introduced a mechanism to initialize the SWIOTLB when the Xen PCI front moves to Connected state. It also had some aggressive seatbelt code check that would warn the user if one tried to change to Connected state without hitting first the Closing state: pcifront pci-0: PCI frontend already installed! However, that code can be relaxed and we can continue on working even if the frontend is instructed to be the 'Connected' state with no devices and then gets tickled to be in 'Connected' state again. In other words, this 4(Connected)->5(Closing)->4(Connected) state was expected, while 4(Connected)->.... anything but 5(Closing)->4(Connected) was not. This patch removes that aggressive check and allows Xen pcifront to work with the 'xl' toolstack (for one or more PCI devices) and with 'xm' toolstack (for more than two PCI devices). Acked-by: Bjorn Helgaas <bhelgaas@google.com> Cc: linux-pci@vger.kernel.org [v2: Added in the description about two PCI devices] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/pci/xen-pcifront.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 966abc6054d..f7197a79034 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -678,10 +678,9 @@ static int pcifront_connect_and_init_dma(struct pcifront_device *pdev)
if (!pcifront_dev) {
dev_info(&pdev->xdev->dev, "Installing PCI frontend\n");
pcifront_dev = pdev;
- } else {
- dev_err(&pdev->xdev->dev, "PCI frontend already installed!\n");
+ } else
err = -EEXIST;
- }
+
spin_unlock(&pcifront_dev_lock);
if (!err && !swiotlb_nr_tbl()) {
@@ -848,7 +847,7 @@ static int pcifront_try_connect(struct pcifront_device *pdev)
goto out;
err = pcifront_connect_and_init_dma(pdev);
- if (err) {
+ if (err && err != -EEXIST) {
xenbus_dev_fatal(pdev->xdev, err,
"Error setting up PCI Frontend");
goto out;