Hi Chao,
Thanks for the review!
On 2/4/2026 3:43 PM, Chao Liu wrote:
Hi Fengyuan,
On Wed, Feb 04, 2026 at 11:06:20AM +0800, Fengyuan Yu wrote:
Add a qtest suite for the Intel IOMMU (VT-d) device on the Q35 machine.
The test exercises pass-through and translated translation modes using
iommu-testdev and the qos-intel-iommu helpers.
The test validates:
- Root Entry Table and Context Entry Table configuration
- 4-level page table walks for 48-bit address translation
- Pass-through mode (identity mapping)
- Translated mode with complete IOVA-to-PA translation
- DMA transaction execution with memory content verification
Good commit message.
Signed-off-by: Fengyuan Yu <[email protected]>
---
tests/qtest/iommu-intel-test.c | 137 +++++++++++++++++++++++++++++++++
tests/qtest/meson.build | 2 +
2 files changed, 139 insertions(+)
create mode 100644 tests/qtest/iommu-intel-test.c
diff --git a/tests/qtest/iommu-intel-test.c b/tests/qtest/iommu-intel-test.c
new file mode 100644
index 0000000000..9f631be2c5
--- /dev/null
+++ b/tests/qtest/iommu-intel-test.c
@@ -0,0 +1,137 @@
+/*
+ * QTest for Intel IOMMU (VT-d) with iommu-testdev
+ *
+ * This QTest file is used to test the Intel IOMMU with iommu-testdev so that
+ * we can test VT-d without any guest kernel or firmware.
+ *
+ * Copyright (c) 2026 Fengyuan Yu <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "libqtest.h"
+#include "libqos/pci.h"
+#include "libqos/pci-pc.h"
+#include "hw/pci/pci_regs.h"
+#include "hw/misc/iommu-testdev.h"
+#include "libqos/qos-intel-iommu.h"
+
+#define DMA_LEN 4
+
+/* Test configurations for different Intel IOMMU modes */
+static const QVTDTestConfig base_test_configs[] = {
+ {
+ .trans_mode = QVTD_TM_LEGACY_PT,
+ .dma_iova = 0x10100000, /* Use address in guest RAM range (inside
512MB) */
+ .dma_pa = 0x10100000,
+ .dma_len = DMA_LEN,
+ .expected_result = 0,
+ .domain_id = 1,
+ },
+ {
+ .trans_mode = QVTD_TM_LEGACY_TRANS,
+ .dma_iova = QVTD_TEST_IOVA,
+ .dma_pa = QVTD_TEST_PA,
+ .dma_len = DMA_LEN,
+ .expected_result = 0,
+ .domain_id = 1,
+ },
+};
+
+static QPCIDevice *setup_qtest_pci_device(QTestState *qts, QPCIBus **pcibus,
+ QPCIBar *bar)
+{
+ uint16_t vid, did;
+ QPCIDevice *dev = NULL;
+ int device_count = 0;
+
+ *pcibus = qpci_new_pc(qts, NULL);
+ g_assert(*pcibus != NULL);
+
+ g_test_message("Scanning PCI bus for iommu-testdev (vendor:device =
0x%04x:0x%04x)...",
+ IOMMU_TESTDEV_VENDOR_ID, IOMMU_TESTDEV_DEVICE_ID);
+
+ /* Find device by vendor/device ID to avoid slot surprises. */
+ for (int s = 0; s < 32 && !dev; s++) {
+ for (int fn = 0; fn < 8 && !dev; fn++) {
+ QPCIDevice *cand = qpci_device_find(*pcibus, QPCI_DEVFN(s, fn));
+ if (!cand) {
+ continue;
+ }
+ vid = qpci_config_readw(cand, PCI_VENDOR_ID);
+ did = qpci_config_readw(cand, PCI_DEVICE_ID);
+
+ device_count++;
+ g_test_message(" Found PCI device at %02x:%x - vendor:device =
0x%04x:0x%04x",
+ s, fn, vid, did);
+
+ if (vid == IOMMU_TESTDEV_VENDOR_ID &&
+ did == IOMMU_TESTDEV_DEVICE_ID) {
+ dev = cand;
+ g_test_message("Found iommu-testdev! devfn: 0x%x",
cand->devfn);
+ } else {
+ g_free(cand);
+ }
+ }
+ }
+
This manual PCI bus scanning is verbose. The SMMUv3 test uses
qpci_device_foreach() which is more concise:
qpci_device_foreach(&gbus->bus, IOMMU_TESTDEV_VENDOR_ID,
IOMMU_TESTDEV_DEVICE_ID, save_fn, &dev);
See iommu-smmuv3-test.c for reference.
Thanks for the review. I'ill improve the PCI bus scanning in v2.
+ if (!dev) {
+ g_test_message("ERROR: iommu-testdev not found after scanning %d PCI
devices", device_count);
+ g_test_message("Expected vendor:device = 0x%04x:0x%04x
(PCI_VENDOR_ID_REDHAT:PCI_DEVICE_ID_REDHAT_TEST)",
+ IOMMU_TESTDEV_VENDOR_ID, IOMMU_TESTDEV_DEVICE_ID);
+ qpci_free_pc(*pcibus);
+ *pcibus = NULL;
+ g_test_skip("iommu-testdev not found on PCI bus - device may not be
compiled or registered");
+ return NULL;
+ }
+
+ /* Enable device - iommu-testdev only uses MMIO, not I/O ports */
+ uint16_t cmd = qpci_config_readw(dev, PCI_COMMAND);
+ cmd |= PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER;
+ qpci_config_writew(dev, PCI_COMMAND, cmd);
+
+ *bar = qpci_iomap(dev, 0, NULL);
+ g_assert_false(bar->is_io);
+
+ return dev;
+}
+
+static void test_intel_iommu_translation(void)
+{
+ QTestState *qts;
+ QPCIBus *pcibus;
+ QPCIDevice *dev;
+ QPCIBar bar;
+
Please add a machine availability check before qtest_init(), similar to
what the SMMUv3 test does:
Thanks for the review. I'ill add this check in v2.
if (!qtest_has_machine("q35")) {
g_test_skip("q35 machine not available");
return;
}
+ /* Initialize QEMU environment for Intel IOMMU testing */
+ qts = qtest_init("-machine q35,kernel-irqchip=split "
+ "-accel tcg "
+ "-device intel-iommu,pt=on,aw-bits=48 "
+ "-device iommu-testdev,bus=pcie.0,addr=0x4 "
+ "-m 512");
+
+ /* Setup and configure PCI device */
+ dev = setup_qtest_pci_device(qts, &pcibus, &bar);
+ if (!dev) {
+ qtest_quit(qts);
+ return;
+ }
+
+ /* Run the translation tests */
+ g_test_message("### Starting Intel IOMMU translation tests...###");
+ qvtd_translation_batch(base_test_configs, ARRAY_SIZE(base_test_configs),
+ qts, dev, bar, Q35_IOMMU_BASE);
+ g_test_message("### Intel IOMMU translation tests completed successfully!
###");
+
+ g_free(dev);
+ qpci_free_pc(pcibus);
+ qtest_quit(qts);
+}
+
+int main(int argc, char **argv)
+{
+ g_test_init(&argc, &argv, NULL);
+ qtest_add_func("/iommu-testdev/intel-translation",
test_intel_iommu_translation);
The test path naming differs from the SMMUv3 convention. For consistency,
consider splitting into separate test functions and using paths like:
qtest_add_func("/iommu-testdev/intel/legacy-pt", test_intel_legacy_pt);
qtest_add_func("/iommu-testdev/intel/legacy-trans",
test_intel_legacy_trans);
This makes it easier to run individual test cases and debug failures.
Thanks for the review. I will improve the test cases to make them consistent
with the SMMUv3 implementation.
+ return g_test_run();
+}
Missing newline at end of file. Please run scripts/checkpatch.pl check
it.
Thanks for the review. I will carefully use scripts/checkpatch.pl to review the
v2 patch before submitting.
diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index e2d2e68092..344e836300 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -95,6 +95,8 @@ qtests_i386 = \
(config_all_devices.has_key('CONFIG_SDHCI_PCI') ? ['fuzz-sdcard-test'] :
[]) + \
(config_all_devices.has_key('CONFIG_ESP_PCI') ? ['am53c974-test'] : []) +
\
(config_all_devices.has_key('CONFIG_VTD') ? ['intel-iommu-test'] : []) +
\
+ (config_all_devices.has_key('CONFIG_VTD') and
+ config_all_devices.has_key('CONFIG_IOMMU_TESTDEV') ? ['iommu-intel-test'] :
[]) + \
(host_os != 'windows' and
\
config_all_devices.has_key('CONFIG_ACPI_ERST') ? ['erst-test'] : []) +
\
(config_all_devices.has_key('CONFIG_PCIE_PORT') and
\
--
2.39.5
One more thing: the MAINTAINERS entry in patch 1/2 only adds the libqos
files. Please also add to 'X86 general architecture support':
F: tests/qtest/iommu-intel-test.c
to the IOMMU section.
It seems that 'VT-d Emulation' is more appropriate. I will add it to 'VT-d
Emulation' first.
Thanks,
Fengyuan
Overall, this is a nice addition to the IOMMU testing infrastructure.
Thanks,
Chao
