[PATCH v4 07/16] libqos: enforce Device Initialization order

[Stefan Hajnoczi <stefanha@redhat.com>]

According to VIRTIO 1.1 "3.1.1 Driver Requirements: Device
Initialization", configuration space and virtqueues cannot be accessed
before features have been negotiated.  Enforce this requirement.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
v4:
 * Introduce bool d->features_negotiated so that tests can negotiate a
   0 feature bit set in Legacy mode [Thomas]
---
 tests/libqos/virtio.h | 1 +
 tests/libqos/virtio.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/tests/libqos/virtio.h b/tests/libqos/virtio.h
index a5c99fb3c9..0e8f823c7b 100644
--- a/tests/libqos/virtio.h
+++ b/tests/libqos/virtio.h
@@ -23,6 +23,7 @@ typedef struct QVirtioDevice {
     uint16_t device_type;
     uint64_t features;
     bool big_endian;
+    bool features_negotiated;
 } QVirtioDevice;
 
 typedef struct QVirtQueue {
diff --git a/tests/libqos/virtio.c b/tests/libqos/virtio.c
index 4f7e6bb8a1..6049ff3b3e 100644
--- a/tests/libqos/virtio.c
+++ b/tests/libqos/virtio.c
@@ -15,21 +15,25 @@
 
 uint8_t qvirtio_config_readb(QVirtioDevice *d, uint64_t addr)
 {
+    g_assert_true(d->features_negotiated);
     return d->bus->config_readb(d, addr);
 }
 
 uint16_t qvirtio_config_readw(QVirtioDevice *d, uint64_t addr)
 {
+    g_assert_true(d->features_negotiated);
     return d->bus->config_readw(d, addr);
 }
 
 uint32_t qvirtio_config_readl(QVirtioDevice *d, uint64_t addr)
 {
+    g_assert_true(d->features_negotiated);
     return d->bus->config_readl(d, addr);
 }
 
 uint64_t qvirtio_config_readq(QVirtioDevice *d, uint64_t addr)
 {
+    g_assert_true(d->features_negotiated);
     return d->bus->config_readq(d, addr);
 }
 
@@ -42,11 +46,13 @@ void qvirtio_set_features(QVirtioDevice *d, uint64_t features)
 {
     d->features = features;
     d->bus->set_features(d, features);
+    d->features_negotiated = true;
 }
 
 QVirtQueue *qvirtqueue_setup(QVirtioDevice *d,
                              QGuestAllocator *alloc, uint16_t index)
 {
+    g_assert_true(d->features_negotiated);
     return d->bus->virtqueue_setup(d, alloc, index);
 }
 
@@ -60,6 +66,7 @@ void qvirtio_reset(QVirtioDevice *d)
 {
     d->bus->set_status(d, 0);
     g_assert_cmphex(d->bus->get_status(d), ==, 0);
+    d->features_negotiated = false;
 }
 
 void qvirtio_set_acknowledge(QVirtioDevice *d)
-- 
2.21.0