From: David Matlack Extend the eventfd IRQ test with a '-d' argument that takes a BDF (in the format segment:bus:device.function) of an interrupt-capable PCI(e) device bound to VFIO, and use said device to trigger interrupts instead of always synthesizing interrupts via direct writes to the eventfd. Using a VFIO device to trigger interrupts validates the end-to-end delivery of IRQs for "real" devices, and when supported by hardware (and KVM), also validates interrupt delivery via IRQ bypass, i.e. via device posted IRQs. Now that IOMMUFD is a thing, auto-probe IOMMUFD vs. "legacy" VFIO by temporarily opening /dev/iommufd, and skip the test if neither IOMMUFD nor legacy VFIO is available. Add a '-t' option to the user override the probe logic, e.g. in case IOMMUFD is available but the system is configured for legacy usage. Note, the device must have a VFIO selftest driver in order to work with the test. A helper script to list supported devices will hopefully be available in the near future at tools/testing/selftests/vfio/scripts/list_supported_devices.sh[1]. Example: $ ./tools/testing/selftests/kvm/irq_test -d 0000:06:0a.1 Link: https://lore.kernel.org/all/20260602222941.3133236-1-jrhilke%40google.com [1] Signed-off-by: David Matlack Co-developed-by: Josh Hilke Signed-off-by: Josh Hilke Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/irq_test.c | 86 ++++++++++++++++++++++++-- 1 file changed, 80 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/kvm/irq_test.c b/tools/testing/selftests/kvm/irq_test.c index 9f8895b89821..6888be54ee4a 100644 --- a/tools/testing/selftests/kvm/irq_test.c +++ b/tools/testing/selftests/kvm/irq_test.c @@ -3,7 +3,10 @@ #include "test_util.h" #include "apic.h" #include "processor.h" +#include "proc_util.h" +#include +#include #include #include #include @@ -55,6 +58,36 @@ static void *vcpu_thread_main(void *arg) return NULL; } +static int vfio_setup_msi(struct vfio_pci_device *device) +{ + const int flags = MAP_SHARED | MAP_ANONYMOUS; + const int prot = PROT_READ | PROT_WRITE; + struct dma_region *region; + + /* 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 = kvm_mmap(region->size, prot, flags, -1); + TEST_ASSERT(region->vaddr != MAP_FAILED, "mmap() failed\n"); + iommu_map(device->iommu, region); + + vfio_pci_driver_init(device); + return device->driver.msi; +} + +static void trigger_interrupt(struct vfio_pci_device *device, int eventfd) +{ + if (device) + vfio_pci_driver_send_msi(device); + else + eventfd_write(eventfd, 1); +} + + static void kvm_route_msi(struct kvm_vm *vm, u32 gsi, struct kvm_vcpu *vcpu, u8 vector) { @@ -74,11 +107,29 @@ static void kvm_route_msi(struct kvm_vm *vm, u32 gsi, struct kvm_vcpu *vcpu, vm_ioctl(vm, KVM_SET_GSI_ROUTING, &routing.header); } +static const char *probe_iommu_type(void) +{ + int io_fd; + + io_fd = open("/dev/iommu", O_RDONLY); + if (io_fd >= 0) { + close(io_fd); + return MODE_IOMMUFD; + } + + io_fd = __open_path_or_exit("/dev/vfio", O_RDONLY, + "Is VFIO (or IOMMUFD) loaded and enabled?"); + close(io_fd); + return MODE_VFIO_TYPE1_IOMMU; +} + static void help(const char *name) { - printf("Usage: %s [-h]\n", name); + printf("Usage: %s [-d ] [-h] [-t iommu_type]\n", name); printf("\n"); printf("Tests KVM interrupt routing and delivery via irqfd.\n"); + printf("-d Use a VFIO device to send MSI-X interrupts instead of manually signaling the eventfd\n"); + printf("-t Override the IOMMU type to use (vfio_type1_iommu or iommufd)\n"); printf("\n"); exit(KSFT_FAIL); } @@ -100,14 +151,25 @@ int main(int argc, char **argv) u32 gsi = kvm_random_u64_in_range(&kvm_rng, 24, KVM_MAX_IRQ_ROUTES - 1); u8 vector = kvm_random_u64_in_range(&kvm_rng, 32, UINT8_MAX); - struct kvm_vcpu *vcpus[KVM_MAX_VCPUS]; pthread_t vcpu_threads[KVM_MAX_VCPUS]; + struct kvm_vcpu *vcpus[KVM_MAX_VCPUS]; + struct vfio_pci_device *device = NULL; int nr_irqs = 1000, nr_vcpus = 1; - int i, j, c, eventfd; + const char *device_bdf = NULL; + const char *iommu_type = NULL; + int i, j, c, msix, eventfd; + struct iommu *iommu; struct kvm_vm *vm; + int irq; - while ((c = getopt(argc, argv, "h")) != -1) { + while ((c = getopt(argc, argv, "d:ht:")) != -1) { switch (c) { + case 'd': + device_bdf = optarg; + break; + case 't': + iommu_type = optarg; + break; case 'h': default: help(argv[0]); @@ -119,7 +181,19 @@ int main(int argc, char **argv) vm = vm_create_with_vcpus(nr_vcpus, guest_code, vcpus); vm_install_exception_handler(vm, vector, guest_irq_handler); - eventfd = kvm_new_eventfd(); + if (device_bdf) { + if (!iommu_type) + iommu_type = probe_iommu_type(); + iommu = iommu_init(iommu_type); + device = vfio_pci_device_init(device_bdf, iommu); + msix = vfio_setup_msi(device); + irq = vfio_msix_to_host_irq(device_bdf, msix); + eventfd = device->msi_eventfds[msix]; + printf("Using device %s MSI-X[%d] (IRQ-%u)\n", device_bdf, msix, + irq); + } else { + eventfd = kvm_new_eventfd(); + } pr_info("Injecting interrupts for GSI %d (guest vector 0x%x) %d times\n", gsi, vector, nr_irqs); @@ -147,7 +221,7 @@ int main(int argc, char **argv) "IRQ flag for vCPU %d not clear prior to test", vcpus[j]->id); - eventfd_write(eventfd, 1); + trigger_interrupt(device, eventfd); clock_gettime(CLOCK_MONOTONIC, &start); while (!GUEST_RECEIVED_IRQ(vcpu) && -- 2.54.0.1099.g489fc7bff1-goog