diff mbox series

[RFC,33/33] KVM: selftests: Use real device MSIs in vfio_pci_device_irq_test

Message ID 20250523233018.1702151-34-dmatlack@google.com
State New
Headers show
Series [RFC,01/33] selftests: Create tools/testing/selftests/vfio | expand

Commit Message

David Matlack May 23, 2025, 11:30 p.m. UTC
Use real device MSIs to deliver interrupts into the guest in
vfio_pci_device_irq_test (when possible). If the device has a driver, we
can use the driver to make the device send a physical MSI, rather than
synthesizing an eventfd notification in software. This allows this test
to exercise IRQ Bypass (e.g. VT-d device-posted interrupts in Intel).

Signed-off-by: David Matlack <dmatlack@google.com>
---
 .../selftests/kvm/vfio_pci_device_irq_test.c  | 66 +++++++++++++++----
 1 file changed, 55 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/tools/testing/selftests/kvm/vfio_pci_device_irq_test.c b/tools/testing/selftests/kvm/vfio_pci_device_irq_test.c
index c792fc169028..8cbaf38357c4 100644
--- a/tools/testing/selftests/kvm/vfio_pci_device_irq_test.c
+++ b/tools/testing/selftests/kvm/vfio_pci_device_irq_test.c
@@ -7,6 +7,8 @@ 
 #include <pthread.h>
 #include <time.h>
 #include <linux/vfio.h>
+#include <linux/sizes.h>
+
 #include <vfio_util.h>
 
 static bool guest_ready_for_irq;
@@ -60,11 +62,54 @@  void *vcpu_thread_main(void *arg)
 
 static void help(const char *name)
 {
-	printf("Usage: %s [-i iommu_mode] segment:bus:device.function\n", name);
+	printf("Usage: %s [-i iommu_mode] [-d] segment:bus:device.function\n", name);
+	printf("  -d: Send a real MSI from the device, rather than synthesizing\n"
+	       "      an eventfd signal from VFIO. Note that this option requires\n"
+	       "      a VFIO selftests driver that supports the device.\n");
 	iommu_mode_help("-i");
 	exit(1);
 }
 
+static int setup_msi(struct vfio_pci_device *device, bool use_device_msi)
+{
+	const int flags = MAP_SHARED | MAP_ANONYMOUS;
+	const int prot = PROT_READ | PROT_WRITE;
+	struct vfio_dma_region *region;
+
+	if (use_device_msi) {
+		/* A driver is required to generate an MSI. */
+		TEST_REQUIRE(device->driver.ops);
+
+		/* Set up a DMA-able region for the driver to use. */
+		region = &device->driver.region;
+		region->iova = 0;
+		region->size = SZ_2M;
+		region->vaddr = mmap(NULL, region->size, prot, flags, -1, 0);
+		TEST_ASSERT(region->vaddr != MAP_FAILED, "mmap() failed\n");
+		vfio_pci_dma_map(device, region);
+
+		vfio_pci_driver_init(device);
+
+		return device->driver.msi;
+	}
+
+	TEST_REQUIRE(device->msix_info.count > 0);
+	vfio_pci_msix_enable(device, 0, 1);
+	return 0;
+}
+
+static void send_msi(struct vfio_pci_device *device, bool use_device_msi, int msi)
+{
+	if (use_device_msi) {
+		printf("Sending MSI %d from the device\n", msi);
+		TEST_ASSERT_EQ(msi, device->driver.msi);
+		vfio_pci_driver_send_msi(device);
+	} else {
+		printf("Notifying the eventfd for MSI %d from VFIO\n", msi);
+		vfio_pci_irq_trigger(device, VFIO_PCI_MSIX_IRQ_INDEX, msi);
+	}
+}
+
 int main(int argc, char **argv)
 {
 	/* Random non-reserved vector and GSI to use for the device IRQ */
@@ -74,16 +119,21 @@  int main(int argc, char **argv)
 	struct timespec start, elapsed;
 	struct vfio_pci_device *device;
 	const char *iommu_mode = NULL;
+	bool use_device_msi = false;
 	struct kvm_vcpu *vcpu;
 	pthread_t vcpu_thread;
 	struct kvm_vm *vm;
+	int msi;
 	int c;
 
-	while ((c = getopt(argc, argv, "i:")) != -1) {
+	while ((c = getopt(argc, argv, "i:d")) != -1) {
 		switch (c) {
 		case 'i':
 			iommu_mode = optarg;
 			break;
+		case 'd':
+			use_device_msi = true;
+			break;
 		default:
 			help(argv[0]);
 		}
@@ -96,10 +146,9 @@  int main(int argc, char **argv)
 	vm_install_exception_handler(vm, vector, guest_irq_handler);
 
 	device = vfio_pci_device_init(argv[optind], iommu_mode);
-	TEST_REQUIRE(device->msix_info.count > 0);
+	msi = setup_msi(device, use_device_msi);
 
-	vfio_pci_msix_enable(device, 0, 1);
-	kvm_add_irqfd(vm, gsi, device->msi_eventfds[0]);
+	kvm_add_irqfd(vm, gsi, device->msi_eventfds[msi]);
 	kvm_route_msi(vm, gsi, vcpu, vector);
 
 	pthread_create(&vcpu_thread, NULL, vcpu_thread_main, vcpu);
@@ -107,12 +156,7 @@  int main(int argc, char **argv)
 	while (!READ_ONCE(guest_ready_for_irq))
 		sync_global_from_guest(vm, guest_ready_for_irq);
 
-	/*
-	 * TODO: Get the device to send a physical MSI to exercise IRQ Bypass
-	 * (e.g. VT-d on Intel), rather than manually synthesizing a
-	 * notification from VFIO.
-	 */
-	vfio_pci_irq_trigger(device, VFIO_PCI_MSIX_IRQ_INDEX, 0);
+	send_msi(device, use_device_msi, msi);
 
 	clock_gettime(CLOCK_MONOTONIC, &start);