From c4a89076814a915d3db4680df7138930d8d12ffb Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Tue, 6 Jun 2017 06:57:31 +0200
Subject: [PATCH 08/17] kvm: irqchip: skip update msi when disabled

RH-Author: Peter Xu <peterx@redhat.com>
Message-id: <1496732251-27935-4-git-send-email-peterx@redhat.com>
Patchwork-id: 75490
O-Subject: [RHEL7.4 qemu-kvm-rhev PATCH 3/3] kvm: irqchip: skip update msi when disabled
Bugzilla: 1448813
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Xiao Wang <jasowang@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

It's possible that one device kept its irqfd/virq there even when
MSI/MSIX was disabled globally for that device. One example is
virtio-net-pci (see commit f1d0f15a6 and virtio_pci_vq_vector_mask()).
It is used as a fast path to avoid allocate/release irqfd/virq
frequently when guest enables/disables MSIX.

However, this fast path brought a problem to msi_route_list, that the
device MSIRouteEntry is still dangling there even if MSIX disabled -
then we cannot know which message to fetch, even if we can, the messages
are meaningless. In this case, we can just simply ignore this entry.

It's safe, since when MSIX is enabled again, we'll rebuild them no
matter what.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1448813

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <1494309644-18743-4-git-send-email-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 207aa6d44ce2cbd2444eac9cea0d853a4265303e)
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

Conflicts:
  target/i386/kvm.c

The conflict is caused by missing of upstream commit 795c40b8
("migration: Create migration/blocker.h"), which removed the include of
"migration/migration.h" but introduced "migration/blocker.h".
---
 target/i386/kvm.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index cfd7695..c3fae53 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -43,6 +43,7 @@
 #include "standard-headers/asm-x86/hyperv.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/msi.h"
+#include "hw/pci/msix.h"
 #include "migration/migration.h"
 #include "exec/memattrs.h"
 #include "trace.h"
@@ -3510,12 +3511,17 @@ static void kvm_update_msi_routes_all(void *private, bool global,
     int cnt = 0;
     MSIRouteEntry *entry;
     MSIMessage msg;
+    PCIDevice *dev;
+
     /* TODO: explicit route update */
     QLIST_FOREACH(entry, &msi_route_list, list) {
         cnt++;
-        msg = pci_get_msi_message(entry->dev, entry->vector);
-        kvm_irqchip_update_msi_route(kvm_state, entry->virq,
-                                     msg, entry->dev);
+        dev = entry->dev;
+        if (!msix_enabled(dev) && !msi_enabled(dev)) {
+            continue;
+        }
+        msg = pci_get_msi_message(dev, entry->vector);
+        kvm_irqchip_update_msi_route(kvm_state, entry->virq, msg, dev);
     }
     kvm_irqchip_commit_routes(kvm_state);
     trace_kvm_x86_update_msi_routes(cnt);
-- 
1.8.3.1