Add the -d option to vfio_pci_device_irq_test that will make the device
send an MSI rather than synthesizing an eventfd notification from VFIO.
This requires a VFIO selftest driver for the device that supports the
send_msi() function.

This option allows the test to exercise IRQ Bypass (e.g. VT-d
device-posted interrupts in Intel).

Signed-off-by: David Matlack <dmatl...@google.com>
---
 .../selftests/kvm/vfio_pci_device_irq_test.c  | 61 +++++++++++++++++--
 1 file changed, 55 insertions(+), 6 deletions(-)

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 9b90cf9dd38f..64fd4efe2096 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;
@@ -60,10 +62,53 @@ 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");
        exit(KSFT_FAIL);
 }
 
+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 */
@@ -73,19 +118,24 @@ 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;
        const char *device_bdf;
        struct kvm_vcpu *vcpu;
        pthread_t vcpu_thread;
        struct kvm_vm *vm;
+       int msi;
        int c;
 
        device_bdf = vfio_selftests_get_bdf(&argc, argv);
 
-       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]);
                }
@@ -95,10 +145,9 @@ int main(int argc, char **argv)
        vm_install_exception_handler(vm, vector, guest_irq_handler);
 
        device = vfio_pci_device_init(device_bdf, 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);
@@ -106,7 +155,7 @@ int main(int argc, char **argv)
        while (!READ_ONCE(guest_ready_for_irq))
                sync_global_from_guest(vm, guest_ready_for_irq);
 
-       vfio_pci_irq_trigger(device, VFIO_PCI_MSIX_IRQ_INDEX, 0);
+       send_msi(device, use_device_msi, msi);
 
        clock_gettime(CLOCK_MONOTONIC, &start);
 
-- 
2.50.0.rc2.701.gf1e915cc24-goog


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