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From fdad8c197b91f1010e4f61147f27513a4f061e40 Mon Sep 17 00:00:00 2001
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From: Alex Williamson <alex.williamson@redhat.com>
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Date: Mon, 12 Jan 2015 04:52:17 +0100
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Subject: [PATCH 1/3] vfio-pci: Fix interrupt disabling
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Message-id: <20150112045144.9215.59820.stgit@gimli.home>
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Patchwork-id: 63242
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O-Subject: [RHEL7.1 qemu-kvm PATCH] vfio-pci: Fix interrupt disabling
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Bugzilla: 1180942
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Acked-by: Bandan Das <bsd@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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Upstream: b3e27c3aee8f5a96debfe0346e9c0e3a641a8516
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When disabling MSI/X interrupts the disable functions will leave the
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device in INTx mode (when available). This matches how hardware
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operates, INTx is enabled unless MSI/X is enabled (DisINTx is handled
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separately). Therefore when we really want to disable all interrupts,
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such as when removing the device, and we start with the device in
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MSI/X mode, we need to pass through INTx on our way to being
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completely quiesced.
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In well behaved situations, the guest driver will have shutdown the
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device and it will start vfio_exitfn() in INTx mode, producing the
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desired result. If hot-unplug causes the guest to crash, we may get
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the device in MSI/X state, which will leave QEMU with a bogus handler
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installed.
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Fix this by re-ordering our disable routine so that it should always
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finish in VFIO_INT_NONE state, which is what all callers expect.
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Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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hw/misc/vfio.c | 21 ++++++++++++---------
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1 file changed, 12 insertions(+), 9 deletions(-)
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diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
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index abaa4c1..40b0923 100644
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--- a/hw/misc/vfio.c
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+++ b/hw/misc/vfio.c
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@@ -2353,16 +2353,19 @@ static void vfio_listener_release(VFIOContainer *container)
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*/
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static void vfio_disable_interrupts(VFIODevice *vdev)
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{
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- switch (vdev->interrupt) {
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- case VFIO_INT_INTx:
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- vfio_disable_intx(vdev);
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- break;
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- case VFIO_INT_MSI:
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- vfio_disable_msi(vdev);
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- break;
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- case VFIO_INT_MSIX:
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+ /*
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+ * More complicated than it looks. Disabling MSI/X transitions the
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+ * device to INTx mode (if supported). Therefore we need to first
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+ * disable MSI/X and then cleanup by disabling INTx.
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+ */
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+ if (vdev->interrupt == VFIO_INT_MSIX) {
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vfio_disable_msix(vdev);
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- break;
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+ } else if (vdev->interrupt == VFIO_INT_MSI) {
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+ vfio_disable_msi(vdev);
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+ }
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+
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+ if (vdev->interrupt == VFIO_INT_INTx) {
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+ vfio_disable_intx(vdev);
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}
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}
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--
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1.8.3.1
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