[PATCH 1/4] tests/qtest: Enforce zero for the "un-fired" msix message value

[Nicholas Piggin <npiggin@gmail.com>]

virtio-pci detects an unmasked msix interrupt has fired by looking
for the data payload value at the target address. If a value of zero
is enforced for the memory value when an interrupt has not fired,
then an assertion can be added to catch the case where something
changed the memory to an unexpected value.

This catches an endian conversion bug in the message value when
running these tests on a big endian target. Previously the test
just times out waiting for interrupt, after this it fails nicely.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 tests/qtest/libqos/virtio-pci-modern.c |  9 +++++----
 tests/qtest/libqos/virtio-pci.c        | 20 ++++++++++++--------
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/tests/qtest/libqos/virtio-pci-modern.c b/tests/qtest/libqos/virtio-pci-modern.c
index 4e67fcbd5d3..f31b3be656d 100644
--- a/tests/qtest/libqos/virtio-pci-modern.c
+++ b/tests/qtest/libqos/virtio-pci-modern.c
@@ -137,12 +137,13 @@ static bool get_msix_status(QVirtioPCIDevice *dev, uint32_t msix_entry,
     }
 
     data = qtest_readl(dev->pdev->bus->qts, msix_addr);
-    if (data == msix_data) {
-        qtest_writel(dev->pdev->bus->qts, msix_addr, 0);
-        return true;
-    } else {
+    if (data == 0) {
         return false;
     }
+    /* got a message, ensure it matches expected value then clear it. */
+    g_assert_cmphex(data, ==, msix_data);
+    qtest_writel(dev->pdev->bus->qts, msix_addr, 0);
+    return true;
 }
 
 static bool get_queue_isr_status(QVirtioDevice *d, QVirtQueue *vq)
diff --git a/tests/qtest/libqos/virtio-pci.c b/tests/qtest/libqos/virtio-pci.c
index 002bf8b8c2d..102e45b5248 100644
--- a/tests/qtest/libqos/virtio-pci.c
+++ b/tests/qtest/libqos/virtio-pci.c
@@ -132,12 +132,13 @@ static bool qvirtio_pci_get_queue_isr_status(QVirtioDevice *d, QVirtQueue *vq)
             return qpci_msix_pending(dev->pdev, vqpci->msix_entry);
         } else {
             data = qtest_readl(dev->pdev->bus->qts, vqpci->msix_addr);
-            if (data == vqpci->msix_data) {
-                qtest_writel(dev->pdev->bus->qts, vqpci->msix_addr, 0);
-                return true;
-            } else {
+            if (data == 0) {
                 return false;
             }
+            /* got a message, ensure it matches expected value then clear it. */
+            g_assert_cmphex(data, ==, vqpci->msix_data);
+            qtest_writel(dev->pdev->bus->qts, vqpci->msix_addr, 0);
+            return true;
         }
     } else {
         return qpci_io_readb(dev->pdev, dev->bar, VIRTIO_PCI_ISR) & 1;
@@ -156,12 +157,13 @@ static bool qvirtio_pci_get_config_isr_status(QVirtioDevice *d)
             return qpci_msix_pending(dev->pdev, dev->config_msix_entry);
         } else {
             data = qtest_readl(dev->pdev->bus->qts, dev->config_msix_addr);
-            if (data == dev->config_msix_data) {
-                qtest_writel(dev->pdev->bus->qts, dev->config_msix_addr, 0);
-                return true;
-            } else {
+            if (data == 0) {
                 return false;
             }
+            /* got a message, ensure it matches expected value then clear it. */
+            g_assert_cmphex(data, ==, dev->config_msix_data);
+            qtest_writel(dev->pdev->bus->qts, dev->config_msix_addr, 0);
+            return true;
         }
     } else {
         return qpci_io_readb(dev->pdev, dev->bar, VIRTIO_PCI_ISR) & 2;
@@ -323,6 +325,7 @@ void qvirtqueue_pci_msix_setup(QVirtioPCIDevice *d, QVirtQueuePCI *vqpci,
     vqpci->msix_entry = entry;
 
     vqpci->msix_addr = guest_alloc(alloc, 4);
+    qtest_memset(d->pdev->bus->qts, vqpci->msix_addr, 0, 4);
     qpci_io_writel(d->pdev, d->pdev->msix_table_bar,
                    off + PCI_MSIX_ENTRY_LOWER_ADDR, vqpci->msix_addr & ~0UL);
     qpci_io_writel(d->pdev, d->pdev->msix_table_bar,
@@ -355,6 +358,7 @@ void qvirtio_pci_set_msix_configuration_vector(QVirtioPCIDevice *d,
 
     d->config_msix_data = 0x12345678;
     d->config_msix_addr = guest_alloc(alloc, 4);
+    qtest_memset(d->pdev->bus->qts, d->config_msix_addr, 0, 4);
 
     qpci_io_writel(d->pdev, d->pdev->msix_table_bar,
                    off + PCI_MSIX_ENTRY_LOWER_ADDR, d->config_msix_addr & ~0UL);
-- 
2.47.1