libqos: improve event_index test with timeout

The virtio event_index feature lets the device driver tell the device
how many requests to process before raising the next interrupt.
virtio-blk-test.c tries to verify that the device does not raise an
interrupt unnecessarily.

Unfortunately the test has a race condition.  It spins checking for an
interrupt up to 100 times and then assumes the request has finished.  On
a slow host the I/O request could still be in flight and the test would
fail.

This patch waits for the request to complete, or until a 30-second
timeout is reached.  If an interrupt is raised while waiting the test
fails since the device was not supposed to raise interrupts.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Stefan Hajnoczi 2014-09-29 16:40:11 +01:00 committed by Peter Maydell
parent ed9114356b
commit e8c81b4d8a
3 changed files with 31 additions and 4 deletions

View File

@ -91,6 +91,28 @@ bool qvirtio_wait_queue_isr(const QVirtioBus *bus, QVirtioDevice *d,
return timeout != 0;
}
/* Wait for the status byte at given guest memory address to be set
*
* The virtqueue interrupt must not be raised, making this useful for testing
* event_index functionality.
*/
uint8_t qvirtio_wait_status_byte_no_isr(const QVirtioBus *bus,
QVirtioDevice *d,
QVirtQueue *vq,
uint64_t addr,
gint64 timeout_us)
{
gint64 start_time = g_get_monotonic_time();
uint8_t val;
while ((val = readb(addr)) == 0xff) {
clock_step(100);
g_assert(!bus->get_queue_isr_status(d, vq));
g_assert(g_get_monotonic_time() - start_time <= timeout_us);
}
return val;
}
bool qvirtio_wait_config_isr(const QVirtioBus *bus, QVirtioDevice *d,
uint64_t timeout)
{

View File

@ -162,6 +162,11 @@ void qvirtio_set_driver_ok(const QVirtioBus *bus, QVirtioDevice *d);
bool qvirtio_wait_queue_isr(const QVirtioBus *bus, QVirtioDevice *d,
QVirtQueue *vq, uint64_t timeout);
uint8_t qvirtio_wait_status_byte_no_isr(const QVirtioBus *bus,
QVirtioDevice *d,
QVirtQueue *vq,
uint64_t addr,
gint64 timeout_us);
bool qvirtio_wait_config_isr(const QVirtioBus *bus, QVirtioDevice *d,
uint64_t timeout);
QVirtQueue *qvirtqueue_setup(const QVirtioBus *bus, QVirtioDevice *d,

View File

@ -42,6 +42,7 @@
#define TEST_IMAGE_SIZE (64 * 1024 * 1024)
#define QVIRTIO_BLK_TIMEOUT 100
#define QVIRTIO_BLK_TIMEOUT_US (30 * 1000 * 1000)
#define PCI_SLOT 0x04
#define PCI_FN 0x00
@ -595,10 +596,9 @@ static void pci_idx(void)
qvirtqueue_kick(&qvirtio_pci, &dev->vdev, &vqpci->vq, free_head);
/* No notification expected */
g_assert(!qvirtio_wait_queue_isr(&qvirtio_pci, &dev->vdev, &vqpci->vq,
QVIRTIO_BLK_TIMEOUT));
status = readb(req_addr + 528);
status = qvirtio_wait_status_byte_no_isr(&qvirtio_pci, &dev->vdev,
&vqpci->vq, req_addr + 528,
QVIRTIO_BLK_TIMEOUT_US);
g_assert_cmpint(status, ==, 0);
guest_free(alloc, req_addr);