File vfio-ccw-Permit-missing-IRQs.patch of Package qemu

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File vfio-ccw-Permit-missing-IRQs.patch of Package qemu (Revision 7474cc409866f8b34d7ec998f8a280c2)

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From: Eric Farman <farman@linux.ibm.com>
Date: Wed, 21 Apr 2021 17:20:53 +0200
Subject: vfio-ccw: Permit missing IRQs

Git-commit: 6178d4689a1e6a0d2b6dea1dad990e74148fa9d1

Commit 690e29b91102 ("vfio-ccw: Refactor ccw irq handler") changed
one of the checks for the IRQ notifier registration from saying
"the host needs to recognize the only IRQ that exists" to saying
"the host needs to recognize ANY IRQ that exists."

And this worked fine, because the subsequent change to support the
CRW IRQ notifier doesn't get into this code when running on an older
kernel, thanks to a guard by a capability region. The later addition
of the REQ(uest) IRQ by commit b2f96f9e4f5f ("vfio-ccw: Connect the
device request notifier") broke this assumption because there is no
matching capability region. Thus, running new QEMU on an older
kernel fails with:

vfio: unexpected number of irqs 2

Let's adapt the message here so that there's a better clue of what
IRQ is missing.

Furthermore, let's make the REQ(uest) IRQ not fail when attempting
to register it, to permit running vfio-ccw on a newer QEMU with an
older kernel.

Fixes: b2f96f9e4f5f ("vfio-ccw: Connect the device request notifier")
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20210421152053.2379873-1-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jose R. Ziviani <jziviani@suse.de>
---
 hw/vfio/ccw.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
index b2df708e4b0192cc6af898edeca4..400bc07fe260837953de87d0f272 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -412,8 +412,8 @@ static void vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
     }
 
     if (vdev->num_irqs < irq + 1) {
-        error_setg(errp, "vfio: unexpected number of irqs %u",
-                   vdev->num_irqs);
+        error_setg(errp, "vfio: IRQ %u not available (number of irqs %u)",
+                   irq, vdev->num_irqs);
         return;
     }
 
@@ -696,13 +696,15 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
 
     vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_REQ_IRQ_INDEX, &err);
     if (err) {
-        goto out_req_notifier_err;
+        /*
+         * Report this error, but do not make it a failing condition.
+         * Lack of this IRQ in the host does not prevent normal operation.
+         */
+        error_report_err(err);
     }
 
     return;
 
-out_req_notifier_err:
-    vfio_ccw_unregister_irq_notifier(vcdev, VFIO_CCW_CRW_IRQ_INDEX);
 out_crw_notifier_err:
     vfio_ccw_unregister_irq_notifier(vcdev, VFIO_CCW_IO_IRQ_INDEX);
 out_io_notifier_err:

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File vfio-ccw-Permit-missing-IRQs.patch of Package qemu (Revision 7474cc409866f8b34d7ec998f8a280c2)

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