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