From 362cc00162499413d720fd1c9dfcf1fbba762e9b Mon Sep 17 00:00:00 2001 From: David Matlack Date: Fri, 26 Jun 2026 14:35:21 -0700 Subject: [PATCH] KVM: selftests: Add helper to get host IRQ from device MSI-X for IRQ bypass test Introduce proc_util.c and proc_util.h to house utility functions for interacting with the proc filesystem. Add vfio_msix_to_host_irq(), which parses /proc/interrupts, to get the host Linux IRQ for a given VFIO device BDF and MSI-X vector. This helper will be used by the eventfd IRQ test to print the host IRQ number when triggering IRQs via VFIO device, e.g. to aid in debugging if the test fails. Suggested-by: Sean Christopherson Signed-off-by: David Matlack Co-developed-by: Josh Hilke Signed-off-by: Josh Hilke [sean: massage changelog] Link: https://patch.msgid.link/20260626213534.3866178-9-seanjc@google.com Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../testing/selftests/kvm/include/proc_util.h | 9 +++++ tools/testing/selftests/kvm/lib/proc_util.c | 40 +++++++++++++++++++ 3 files changed, 50 insertions(+) create mode 100644 tools/testing/selftests/kvm/include/proc_util.h create mode 100644 tools/testing/selftests/kvm/lib/proc_util.c diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm index 31d92eb493b0..1c87956859dd 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -11,6 +11,7 @@ LIBKVM += lib/kvm_util.c LIBKVM += lib/lru_gen_util.c LIBKVM += lib/memstress.c LIBKVM += lib/guest_sprintf.c +LIBKVM += lib/proc_util.c LIBKVM += lib/rbtree.c LIBKVM += lib/sparsebit.c LIBKVM += lib/test_util.c diff --git a/tools/testing/selftests/kvm/include/proc_util.h b/tools/testing/selftests/kvm/include/proc_util.h new file mode 100644 index 000000000000..704839b6d7af --- /dev/null +++ b/tools/testing/selftests/kvm/include/proc_util.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef SELFTEST_KVM_PROC_UTIL_H +#define SELFTEST_KVM_PROC_UTIL_H + +#include + +unsigned int vfio_msix_to_host_irq(const char *vfio_device_bdf, int msix); + +#endif /* SELFTEST_KVM_PROC_UTIL_H */ diff --git a/tools/testing/selftests/kvm/lib/proc_util.c b/tools/testing/selftests/kvm/lib/proc_util.c new file mode 100644 index 000000000000..84d30f055a0a --- /dev/null +++ b/tools/testing/selftests/kvm/lib/proc_util.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "kvm_util.h" +#include "test_util.h" +#include "proc_util.h" + +static FILE *open_proc_interrupts(void) +{ + FILE *fp; + + fp = fopen("/proc/interrupts", "r"); + TEST_ASSERT(fp, "fopen(/proc/interrupts) failed"); + + return fp; +} + +unsigned int vfio_msix_to_host_irq(const char *device_bdf, int msix) +{ + char search_string[64]; + char line[4096]; + int irq = -1; + FILE *fp; + + fp = open_proc_interrupts(); + + snprintf(search_string, sizeof(search_string), "vfio-msix[%d]", msix); + + while (fgets(line, sizeof(line), fp)) { + if (strstr(line, device_bdf) && strstr(line, search_string)) { + TEST_ASSERT_EQ(1, sscanf(line, "%d:", &irq)); + break; + } + } + + fclose(fp); + + TEST_ASSERT(irq != -1, "Failed to locate IRQ for %s %s", device_bdf, + search_string); + return (unsigned int)irq; +} +