msix: Assert that specified vector is in range

There were several different ways to deal with the situation where the
vector specified for a msix function is out of bound:
- early return a function and keep progresssing
- propagate the error to the caller
- mark msix unusable
- assert it is in bound
- just ignore

An out-of-bound vector should not be specified if the device
implementation is correct so let msix functions always assert that the
specified vector is in range.

An exceptional case is virtio-pci, which allows the guest to configure
vectors. For virtio-pci, it is more appropriate to introduce its own
checks because it is sometimes too late to check the vector range in
msix functions.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20220829083524.143640-1-akihiko.odaki@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Yuval Shaia <yuval.shaia.ml@gmail.com>
Signed-off-by: Akihiko Odaki &lt;<a href="mailto:akihiko.odaki@daynix.com" target="_blank">akihiko.odaki@daynix.com</a>&gt;<br>

1 files changed, 9 insertions, 15 deletions

diff --git a/hw/pci/msix.c b/hw/pci/msix.c
index 1e381a9813..9e70fcd6fa 100644
--- a/hw/pci/msix.c
+++ b/hw/pci/msix.c
@@ -136,17 +136,12 @@ static void msix_handle_mask_update(PCIDevice *dev, int vector, bool was_masked)
     }
 }
 
-void msix_set_mask(PCIDevice *dev, int vector, bool mask, Error **errp)
+void msix_set_mask(PCIDevice *dev, int vector, bool mask)
 {
-    ERRP_GUARD();
     unsigned offset;
     bool was_masked;
 
-    if (vector > dev->msix_entries_nr) {
-        error_setg(errp, "msix: vector %d not allocated. max vector is %d",
-                   vector, dev->msix_entries_nr);
-        return;
-    }
+    assert(vector < dev->msix_entries_nr);
 
     offset = vector * PCI_MSIX_ENTRY_SIZE + PCI_MSIX_ENTRY_VECTOR_CTRL;
 
@@ -522,7 +517,9 @@ void msix_notify(PCIDevice *dev, unsigned vector)
 {
     MSIMessage msg;
 
-    if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector]) {
+    assert(vector < dev->msix_entries_nr);
+
+    if (!dev->msix_entry_used[vector]) {
         return;
     }
 
@@ -558,20 +555,17 @@ void msix_reset(PCIDevice *dev)
  * don't want to follow the spec suggestion can declare all vectors as used. */
 
 /* Mark vector as used. */
-int msix_vector_use(PCIDevice *dev, unsigned vector)
+void msix_vector_use(PCIDevice *dev, unsigned vector)
 {
-    if (vector >= dev->msix_entries_nr) {
-        return -EINVAL;
-    }
-
+    assert(vector < dev->msix_entries_nr);
     dev->msix_entry_used[vector]++;
-    return 0;
 }
 
 /* Mark vector as unused. */
 void msix_vector_unuse(PCIDevice *dev, unsigned vector)
 {
-    if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector]) {
+    assert(vector < dev->msix_entries_nr);
+    if (!dev->msix_entry_used[vector]) {
         return;
     }
     if (--dev->msix_entry_used[vector]) {