hw/virtio: fix double use of a virtio flag

PATCH Superseded Marcel Apfelbaum 4 participants 9 messages Feb 10, 2016 – Feb 23, 2016

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Marcel Apfelbaum

author

2016-02-10 12:22 UTC #0 lore raw

cover hw/virtio: fix double use of a virtio flag

To the obvious question of "how did that happen?"
I can say we had an unlucky break.
Both Jason and me worked on a new different virtio features in the same time, and they were both merged in the same pull request.
We both saw BIT 3 as the last used

    https://lists.gnu.org/archive/html/qemu-devel/2015-11/msg03041.html

Commits 1811e64c and a6df8adf use the same virtio feature bit 4 for different features.

Fix it by using different bits.
While at it, group all the virtio flags into an enum to avoid that in the feature.

Marcel Apfelbaum (2):
hw/virtio: fix double use of a virtio flag
hw/virtio: group virtio flags into an enum

 hw/virtio/virtio-pci.h | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

Signature · 1 line

2.4.3

Marcel Apfelbaum

author

2016-02-10 12:22 UTC #1 lore raw

PATCH 1/2 hw/virtio: fix double use of a virtio flag

Commits 1811e64c and a6df8adf use the same virtio feature bit 4 for different features.

Fix it by using different bits.

Reported-by Laurent Vivier <[email protected]>

Signed-off-by Marcel Apfelbaum <[email protected]>

---
 hw/virtio/virtio-pci.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

hw/virtio/virtio-pci.h +1 -1

index e096e98..6686b10 100644
@@ -71,7 +71,7 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 /* virtio version flags */
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 4
+#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)

Signature · 1 line

2.4.3

Laurent Vivier

Reviewed-by on v1 1/2

2016-02-10 12:57 UTC #2 lore raw

Quoted 17 lines · Marcel Apfelbaum

Commits 1811e64c and a6df8adf use the same virtio feature bit 4 for different features.
Fix it by using different bits.
Reported-by Laurent Vivier <[email protected]>
Signed-off-by Marcel Apfelbaum <[email protected]>
---
 hw/virtio/virtio-pci.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
hw/virtio/virtio-pci.h +0 -0
index e096e98..6686b10 100644

hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 77

Quoted 8 lines

hw/virtio/virtio-pci.h +1 -1

@@ -71,7 +71,7 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 /* virtio version flags */
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 4
+#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)

Reviewed-by Laurent Vivier <[email protected]>

Laurent Vivier

Tested-by on v1 1/2

2016-02-10 13:19 UTC #3 lore raw

In reply to Marcel Apfelbaum

Quoted 17 lines · Marcel Apfelbaum

Commits 1811e64c and a6df8adf use the same virtio feature bit 4 for different features.
Fix it by using different bits.
Reported-by Laurent Vivier <[email protected]>
Signed-off-by Marcel Apfelbaum <[email protected]>
---
 hw/virtio/virtio-pci.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
hw/virtio/virtio-pci.h +0 -0
index e096e98..6686b10 100644

hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 77

Quoted 8 lines

hw/virtio/virtio-pci.h +1 -1

@@ -71,7 +71,7 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 /* virtio version flags */
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 4
+#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)

Tested-by Laurent Vivier <[email protected]>

pc-i440fx-2.4
migrate-extra = false
x-disable-pcie = true

pc-i440fx-2.5
migrate-extra = true
x-disable-pcie = false

This is correct, now.

Thanks,
Laurent

Jason Wang

Acked-by on v1 1/2

2016-02-23 03:35 UTC #4 lore raw

In reply to Marcel Apfelbaum

Quoted 16 lines · Marcel Apfelbaum

Commits 1811e64c and a6df8adf use the same virtio feature bit 4 for different features.
Fix it by using different bits.
Reported-by Laurent Vivier <[email protected]>
Signed-off-by Marcel Apfelbaum <[email protected]>
---
 hw/virtio/virtio-pci.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
hw/virtio/virtio-pci.h +0 -0
index e096e98..6686b10 100644

hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 77

Quoted 8 lines

hw/virtio/virtio-pci.h +1 -1

@@ -71,7 +71,7 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 /* virtio version flags */
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 4
+#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)

Acked-by Jason Wang <[email protected]>

Marcel Apfelbaum

author

2016-02-10 12:22 UTC #5 lore raw

PATCH 2/2 hw/virtio: group virtio flags into an enum

In reply to Marcel Apfelbaum

Minimizes the possibility to assign
the same bit to different features.

Signed-off-by Marcel Apfelbaum <[email protected]>

---
 hw/virtio/virtio-pci.h | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

hw/virtio/virtio-pci.h +10 -6

index 6686b10..817bcde 100644
@@ -58,6 +58,16 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 #define VIRTIO_PCI_BUS_CLASS(klass) \
         OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS)
 
+enum {
+    VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT,
+    VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT,
+    VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT,
+    VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT,
+};
+
 /* Need to activate work-arounds for buggy guests at vmstate load. */
 #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT  0
 #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \

@@ -65,23 +75,17 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 
 /* Performance improves when virtqueue kick processing is decoupled from the
  * vcpu thread using ioeventfd for some devices. */
-#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
 #define VIRTIO_PCI_FLAG_USE_IOEVENTFD   (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
 
 /* virtio version flags */
-#define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
-#define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)
 
 /* migrate extra state */
-#define VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT 4
 #define VIRTIO_PCI_FLAG_MIGRATE_EXTRA (1 << VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT)
 
 /* have pio notification for modern device ? */
-#define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT 5
 #define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY \
     (1 << VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT)

Signature · 1 line

2.4.3

Laurent Vivier

2016-02-10 13:07 UTC #6 lore raw

Re: [Qemu-devel] [PATCH 2/2] hw/virtio: group virtio flags into an enum

Quoted 15 lines · Marcel Apfelbaum

Minimizes the possibility to assign
the same bit to different features.

Signed-off-by Marcel Apfelbaum <[email protected]>

---
 hw/virtio/virtio-pci.h | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

hw/virtio/virtio-pci.h +0 -0

index 6686b10..817bcde 100644
@@ -58,6 +58,16 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 #define VIRTIO_PCI_BUS_CLASS(klass) \
         OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS)

hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 69

Quoted 10 lines

hw/virtio/virtio-pci.h +9 -0

 
+enum {
+    VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT,
+    VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT,
+    VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT,
+    VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT,
+};

You can keep the "#define", doing something like this after the enum:

#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT

So, if someone includes this ".h" out of qemu and wants to use some "#ifdef" to see if the bit is defined, it always works. (see for an example, /usr/include/linux/rtnetlink.h).

hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 72

Quoted 3 lines

hw/virtio/virtio-pci.h +1 -0

+
 /* Need to activate work-arounds for buggy guests at vmstate load. */
 #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT  0

You should remove this one too.

Quoted 26 lines

hw/virtio/virtio-pci.h +0 -6

 #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \

@@ -65,23 +75,17 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 
 /* Performance improves when virtqueue kick processing is decoupled from the
  * vcpu thread using ioeventfd for some devices. */
-#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
 #define VIRTIO_PCI_FLAG_USE_IOEVENTFD   (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
 
 /* virtio version flags */
-#define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
-#define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)
 
 /* migrate extra state */
-#define VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT 4
 #define VIRTIO_PCI_FLAG_MIGRATE_EXTRA (1 << VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT)
 
 /* have pio notification for modern device ? */
-#define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT 5
 #define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY \
     (1 << VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT)

Marcel Apfelbaum

2016-02-10 13:24 UTC #7 lore raw

Re: [Qemu-devel] [PATCH 2/2] hw/virtio: group virtio flags into an enum

Quoted 31 lines · Laurent Vivier

Quoted 15 lines · Marcel Apfelbaum
Minimizes the possibility to assign
the same bit to different features.
Signed-off-by Marcel Apfelbaum <[email protected]>
---
  hw/virtio/virtio-pci.h | 16 ++++++++++------
  1 file changed, 10 insertions(+), 6 deletions(-)
hw/virtio/virtio-pci.h +0 -0
index 6686b10..817bcde 100644
@@ -58,6 +58,16 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
  #define VIRTIO_PCI_BUS_CLASS(klass) \
          OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS)
hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 69
Quoted 10 lines
hw/virtio/virtio-pci.h +9 -0
 
+enum {
+    VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT,
+    VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT,
+    VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT,
+    VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT,
+};
You can keep the "#define", doing something like this after the enum:

Quoted 5 lines

#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT
So, if someone includes this ".h" out of qemu and wants to use some "#ifdef" to see if the bit is defined, it always works. (see for an example, /usr/include/linux/rtnetlink.h).

Thanks for the idea, but I don't think anyone would want to use those out of qemu :)
I am also afraid that developers will forget to add it to the enum and will still use the defines only.

Quoted 6 lines

hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 72
Quoted 4 lines
hw/virtio/virtio-pci.h +1 -0
+
  /* Need to activate work-arounds for buggy guests at vmstate load. */
  #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT  0
You should remove this one too.

How did I manage to miss it? Thanks!
I'll send a v2
Marcel

Quoted 29 lines

Quoted 27 lines

hw/virtio/virtio-pci.h +0 -6

  #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \

@@ -65,23 +75,17 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 
  /* Performance improves when virtqueue kick processing is decoupled from the
   * vcpu thread using ioeventfd for some devices. */
-#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
  #define VIRTIO_PCI_FLAG_USE_IOEVENTFD   (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
 
  /* virtio version flags */
-#define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
-#define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
  #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
  #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
  #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)
 
  /* migrate extra state */
-#define VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT 4
  #define VIRTIO_PCI_FLAG_MIGRATE_EXTRA (1 << VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT)
 
  /* have pio notification for modern device ? */
-#define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT 5
  #define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY \
      (1 << VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT)

Jason Wang

2016-02-23 03:40 UTC #8 lore raw

Re: [Qemu-devel] [PATCH 2/2] hw/virtio: group virtio flags into an enum

In reply to Marcel Apfelbaum

Quoted 18 lines · Marcel Apfelbaum

Minimizes the possibility to assign
the same bit to different features.

Signed-off-by Marcel Apfelbaum <[email protected]>

---
 hw/virtio/virtio-pci.h | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

hw/virtio/virtio-pci.h +2 -0

index 6686b10..817bcde 100644
@@ -58,6 +58,16 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 #define VIRTIO_PCI_BUS_CLASS(klass) \
         OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS)
 
+enum {
+    VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT,

hw/virtio/virtio-pci.h typedef struct VirtioBusClass VirtioPCIBusClass; · line 72

Quoted 10 lines

hw/virtio/virtio-pci.h +8 -0

+    VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT,
+    VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT,
+    VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT,
+    VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT,
+};
+
 /* Need to activate work-arounds for buggy guests at vmstate load. */
 #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT  0

Why not remove this line too?

Quoted 25 lines

hw/virtio/virtio-pci.h +0 -6

 #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \

@@ -65,23 +75,17 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 
 /* Performance improves when virtqueue kick processing is decoupled from the
  * vcpu thread using ioeventfd for some devices. */
-#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
 #define VIRTIO_PCI_FLAG_USE_IOEVENTFD   (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
 
 /* virtio version flags */
-#define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
-#define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
-#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
 #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)
 
 /* migrate extra state */
-#define VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT 4
 #define VIRTIO_PCI_FLAG_MIGRATE_EXTRA (1 << VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT)
 
 /* have pio notification for modern device ? */
-#define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT 5
 #define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY \
     (1 << VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT)