From 8fd2a6d43a10184f8edcc7adc0547e1871df6705 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 11 Jun 2025 14:35:55 -0700 Subject: KVM: selftests: Fall back to split IRQ chip if full in-kernel chip is unsupported Now that KVM x86 allows compiling out support for in-kernel I/O APIC (and PIC and PIT) emulation, i.e. allows disabling KVM_CREATE_IRQCHIP for all intents and purposes, fall back to a split IRQ chip for x86 if creating the full in-kernel version fails with ENOTTY. Acked-by: Kai Huang Link: https://lore.kernel.org/r/20250611213557.294358-17-seanjc@google.com Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/lib/kvm_util.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index a055343a7bf7..93a921deeb99 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -1716,7 +1716,18 @@ void *addr_gpa2alias(struct kvm_vm *vm, vm_paddr_t gpa) /* Create an interrupt controller chip for the specified VM. */ void vm_create_irqchip(struct kvm_vm *vm) { - vm_ioctl(vm, KVM_CREATE_IRQCHIP, NULL); + int r; + + /* + * Allocate a fully in-kernel IRQ chip by default, but fall back to a + * split model (x86 only) if that fails (KVM x86 allows compiling out + * support for KVM_CREATE_IRQCHIP). + */ + r = __vm_ioctl(vm, KVM_CREATE_IRQCHIP, NULL); + if (r && errno == ENOTTY && kvm_has_cap(KVM_CAP_SPLIT_IRQCHIP)) + vm_enable_cap(vm, KVM_CAP_SPLIT_IRQCHIP, 24); + else + TEST_ASSERT_VM_VCPU_IOCTL(!r, KVM_CREATE_IRQCHIP, r, vm); vm->has_irqchip = true; } -- cgit v1.2.3 From 033b76bc7f066b3e2e024e5ced0de0768d7d57b5 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 22 May 2025 16:52:21 -0700 Subject: KVM: selftests: Assert that eventfd() succeeds in Xen shinfo test Assert that eventfd() succeeds in the Xen shinfo test instead of skipping the associated testcase. While eventfd() is outside the scope of KVM, KVM unconditionally selects EVENTFD, i.e. the syscall should always succeed. Tested-by: K Prateek Nayak Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250522235223.3178519-12-seanjc@google.com Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/x86/xen_shinfo_test.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/x86/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86/xen_shinfo_test.c index 287829f850f7..34d180cf4eed 100644 --- a/tools/testing/selftests/kvm/x86/xen_shinfo_test.c +++ b/tools/testing/selftests/kvm/x86/xen_shinfo_test.c @@ -548,14 +548,11 @@ int main(int argc, char *argv[]) if (do_eventfd_tests) { irq_fd[0] = eventfd(0, 0); - irq_fd[1] = eventfd(0, 0); + TEST_ASSERT(irq_fd[0] >= 0, __KVM_SYSCALL_ERROR("eventfd()", irq_fd[0])); - /* Unexpected, but not a KVM failure */ - if (irq_fd[0] == -1 || irq_fd[1] == -1) - do_evtchn_tests = do_eventfd_tests = false; - } + irq_fd[1] = eventfd(0, 0); + TEST_ASSERT(irq_fd[1] >= 0, __KVM_SYSCALL_ERROR("eventfd()", irq_fd[1])); - if (do_eventfd_tests) { irq_routes.info.nr = 2; irq_routes.entries[0].gsi = 32; -- cgit v1.2.3 From 74e5e3fb0dd71790a1974d63420d43bc5743a56b Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 22 May 2025 16:52:22 -0700 Subject: KVM: selftests: Add utilities to create eventfds and do KVM_IRQFD Add helpers to create eventfds and to (de)assign eventfds via KVM_IRQFD. Tested-by: K Prateek Nayak Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250522235223.3178519-13-seanjc@google.com Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/arm64/vgic_irq.c | 12 ++----- tools/testing/selftests/kvm/include/kvm_util.h | 40 +++++++++++++++++++++++ tools/testing/selftests/kvm/x86/xen_shinfo_test.c | 18 +++------- 3 files changed, 47 insertions(+), 23 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/arm64/vgic_irq.c b/tools/testing/selftests/kvm/arm64/vgic_irq.c index f4ac28d53747..a09dd423c2d7 100644 --- a/tools/testing/selftests/kvm/arm64/vgic_irq.c +++ b/tools/testing/selftests/kvm/arm64/vgic_irq.c @@ -620,18 +620,12 @@ static void kvm_routing_and_irqfd_check(struct kvm_vm *vm, * that no actual interrupt was injected for those cases. */ - for (f = 0, i = intid; i < (uint64_t)intid + num; i++, f++) { - fd[f] = eventfd(0, 0); - TEST_ASSERT(fd[f] != -1, __KVM_SYSCALL_ERROR("eventfd()", fd[f])); - } + for (f = 0, i = intid; i < (uint64_t)intid + num; i++, f++) + fd[f] = kvm_new_eventfd(); for (f = 0, i = intid; i < (uint64_t)intid + num; i++, f++) { - struct kvm_irqfd irqfd = { - .fd = fd[f], - .gsi = i - MIN_SPI, - }; assert(i <= (uint64_t)UINT_MAX); - vm_ioctl(vm, KVM_IRQFD, &irqfd); + kvm_assign_irqfd(vm, i - MIN_SPI, fd[f]); } for (f = 0, i = intid; i < (uint64_t)intid + num; i++, f++) { diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index bee65ca08721..1ddf85eebd1d 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -18,6 +18,7 @@ #include #include +#include #include #include "kvm_util_arch.h" @@ -502,6 +503,45 @@ static inline int vm_get_stats_fd(struct kvm_vm *vm) return fd; } +static inline int __kvm_irqfd(struct kvm_vm *vm, uint32_t gsi, int eventfd, + uint32_t flags) +{ + struct kvm_irqfd irqfd = { + .fd = eventfd, + .gsi = gsi, + .flags = flags, + .resamplefd = -1, + }; + + return __vm_ioctl(vm, KVM_IRQFD, &irqfd); +} + +static inline void kvm_irqfd(struct kvm_vm *vm, uint32_t gsi, int eventfd, + uint32_t flags) +{ + int ret = __kvm_irqfd(vm, gsi, eventfd, flags); + + TEST_ASSERT_VM_VCPU_IOCTL(!ret, KVM_IRQFD, ret, vm); +} + +static inline void kvm_assign_irqfd(struct kvm_vm *vm, uint32_t gsi, int eventfd) +{ + kvm_irqfd(vm, gsi, eventfd, 0); +} + +static inline void kvm_deassign_irqfd(struct kvm_vm *vm, uint32_t gsi, int eventfd) +{ + kvm_irqfd(vm, gsi, eventfd, KVM_IRQFD_FLAG_DEASSIGN); +} + +static inline int kvm_new_eventfd(void) +{ + int fd = eventfd(0, 0); + + TEST_ASSERT(fd >= 0, __KVM_SYSCALL_ERROR("eventfd()", fd)); + return fd; +} + static inline void read_stats_header(int stats_fd, struct kvm_stats_header *header) { ssize_t ret; diff --git a/tools/testing/selftests/kvm/x86/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86/xen_shinfo_test.c index 34d180cf4eed..23909b501ac2 100644 --- a/tools/testing/selftests/kvm/x86/xen_shinfo_test.c +++ b/tools/testing/selftests/kvm/x86/xen_shinfo_test.c @@ -547,11 +547,8 @@ int main(int argc, char *argv[]) int irq_fd[2] = { -1, -1 }; if (do_eventfd_tests) { - irq_fd[0] = eventfd(0, 0); - TEST_ASSERT(irq_fd[0] >= 0, __KVM_SYSCALL_ERROR("eventfd()", irq_fd[0])); - - irq_fd[1] = eventfd(0, 0); - TEST_ASSERT(irq_fd[1] >= 0, __KVM_SYSCALL_ERROR("eventfd()", irq_fd[1])); + irq_fd[0] = kvm_new_eventfd(); + irq_fd[1] = kvm_new_eventfd(); irq_routes.info.nr = 2; @@ -569,15 +566,8 @@ int main(int argc, char *argv[]) vm_ioctl(vm, KVM_SET_GSI_ROUTING, &irq_routes.info); - struct kvm_irqfd ifd = { }; - - ifd.fd = irq_fd[0]; - ifd.gsi = 32; - vm_ioctl(vm, KVM_IRQFD, &ifd); - - ifd.fd = irq_fd[1]; - ifd.gsi = 33; - vm_ioctl(vm, KVM_IRQFD, &ifd); + kvm_assign_irqfd(vm, 32, irq_fd[0]); + kvm_assign_irqfd(vm, 33, irq_fd[1]); struct sigaction sa = { }; sa.sa_handler = handle_alrm; -- cgit v1.2.3 From 7e9b231c402a297251b3e6e0f5cc16cef7dd3ce5 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 22 May 2025 16:52:23 -0700 Subject: KVM: selftests: Add a KVM_IRQFD test to verify uniqueness requirements Add a selftest to verify that eventfd+irqfd bindings are globally unique, i.e. that KVM doesn't allow multiple irqfds to bind to a single eventfd, even across VMs. Tested-by: K Prateek Nayak Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250522235223.3178519-14-seanjc@google.com Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/Makefile.kvm | 1 + tools/testing/selftests/kvm/irqfd_test.c | 135 +++++++++++++++++++++++++++++++ 2 files changed, 136 insertions(+) create mode 100644 tools/testing/selftests/kvm/irqfd_test.c (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm index 38b95998e1e6..028456f1aae1 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -59,6 +59,7 @@ TEST_PROGS_x86 += x86/nx_huge_pages_test.sh TEST_GEN_PROGS_COMMON = demand_paging_test TEST_GEN_PROGS_COMMON += dirty_log_test TEST_GEN_PROGS_COMMON += guest_print_test +TEST_GEN_PROGS_COMMON += irqfd_test TEST_GEN_PROGS_COMMON += kvm_binary_stats_test TEST_GEN_PROGS_COMMON += kvm_create_max_vcpus TEST_GEN_PROGS_COMMON += kvm_page_table_test diff --git a/tools/testing/selftests/kvm/irqfd_test.c b/tools/testing/selftests/kvm/irqfd_test.c new file mode 100644 index 000000000000..7c301b4c7005 --- /dev/null +++ b/tools/testing/selftests/kvm/irqfd_test.c @@ -0,0 +1,135 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include +#include +#include + +#include "kvm_util.h" + +static struct kvm_vm *vm1; +static struct kvm_vm *vm2; +static int __eventfd; +static bool done; + +/* + * KVM de-assigns based on eventfd *and* GSI, but requires unique eventfds when + * assigning (the API isn't symmetrical). Abuse the oddity and use a per-task + * GSI base to avoid false failures due to cross-task de-assign, i.e. so that + * the secondary doesn't de-assign the primary's eventfd and cause assign to + * unexpectedly succeed on the primary. + */ +#define GSI_BASE_PRIMARY 0x20 +#define GSI_BASE_SECONDARY 0x30 + +static void juggle_eventfd_secondary(struct kvm_vm *vm, int eventfd) +{ + int r, i; + + /* + * The secondary task can encounter EBADF since the primary can close + * the eventfd at any time. And because the primary can recreate the + * eventfd, at the safe fd in the file table, the secondary can also + * encounter "unexpected" success, e.g. if the close+recreate happens + * between the first and second assignments. The secondary's role is + * mostly to antagonize KVM, not to detect bugs. + */ + for (i = 0; i < 2; i++) { + r = __kvm_irqfd(vm, GSI_BASE_SECONDARY, eventfd, 0); + TEST_ASSERT(!r || errno == EBUSY || errno == EBADF, + "Wanted success, EBUSY, or EBADF, r = %d, errno = %d", + r, errno); + + /* De-assign should succeed unless the eventfd was closed. */ + r = __kvm_irqfd(vm, GSI_BASE_SECONDARY + i, eventfd, KVM_IRQFD_FLAG_DEASSIGN); + TEST_ASSERT(!r || errno == EBADF, + "De-assign should succeed unless the fd was closed"); + } +} + +static void *secondary_irqfd_juggler(void *ign) +{ + while (!READ_ONCE(done)) { + juggle_eventfd_secondary(vm1, READ_ONCE(__eventfd)); + juggle_eventfd_secondary(vm2, READ_ONCE(__eventfd)); + } + + return NULL; +} + +static void juggle_eventfd_primary(struct kvm_vm *vm, int eventfd) +{ + int r1, r2; + + /* + * At least one of the assigns should fail. KVM disallows assigning a + * single eventfd to multiple GSIs (or VMs), so it's possible that both + * assignments can fail, too. + */ + r1 = __kvm_irqfd(vm, GSI_BASE_PRIMARY, eventfd, 0); + TEST_ASSERT(!r1 || errno == EBUSY, + "Wanted success or EBUSY, r = %d, errno = %d", r1, errno); + + r2 = __kvm_irqfd(vm, GSI_BASE_PRIMARY + 1, eventfd, 0); + TEST_ASSERT(r1 || (r2 && errno == EBUSY), + "Wanted failure (EBUSY), r1 = %d, r2 = %d, errno = %d", + r1, r2, errno); + + /* + * De-assign should always succeed, even if the corresponding assign + * failed. + */ + kvm_irqfd(vm, GSI_BASE_PRIMARY, eventfd, KVM_IRQFD_FLAG_DEASSIGN); + kvm_irqfd(vm, GSI_BASE_PRIMARY + 1, eventfd, KVM_IRQFD_FLAG_DEASSIGN); +} + +int main(int argc, char *argv[]) +{ + pthread_t racing_thread; + int r, i; + + /* Create "full" VMs, as KVM_IRQFD requires an in-kernel IRQ chip. */ + vm1 = vm_create(1); + vm2 = vm_create(1); + + WRITE_ONCE(__eventfd, kvm_new_eventfd()); + + kvm_irqfd(vm1, 10, __eventfd, 0); + + r = __kvm_irqfd(vm1, 11, __eventfd, 0); + TEST_ASSERT(r && errno == EBUSY, + "Wanted EBUSY, r = %d, errno = %d", r, errno); + + r = __kvm_irqfd(vm2, 12, __eventfd, 0); + TEST_ASSERT(r && errno == EBUSY, + "Wanted EBUSY, r = %d, errno = %d", r, errno); + + /* + * De-assign all eventfds, along with multiple eventfds that were never + * assigned. KVM's ABI is that de-assign is allowed so long as the + * eventfd itself is valid. + */ + kvm_irqfd(vm1, 11, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN); + kvm_irqfd(vm1, 12, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN); + kvm_irqfd(vm1, 13, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN); + kvm_irqfd(vm1, 14, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN); + kvm_irqfd(vm1, 10, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN); + + close(__eventfd); + + pthread_create(&racing_thread, NULL, secondary_irqfd_juggler, vm2); + + for (i = 0; i < 10000; i++) { + WRITE_ONCE(__eventfd, kvm_new_eventfd()); + + juggle_eventfd_primary(vm1, __eventfd); + juggle_eventfd_primary(vm2, __eventfd); + close(__eventfd); + } + + WRITE_ONCE(done, true); + pthread_join(racing_thread, NULL); +} -- cgit v1.2.3 From 81bf24f1ac77029bf858c0da081088eb62b1b230 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Thu, 10 Jul 2025 12:12:20 +0100 Subject: KVM: selftests: Add CONFIG_EVENTFD for irqfd selftest In 7e9b231c402a ("KVM: selftests: Add a KVM_IRQFD test to verify uniqueness requirements") we added a test for the newly added irqfd support but since this feature works with eventfds it won't work unless the kernel has been built wth eventfd support. Add CONFIG_EVENTFD to the list of required options for the KVM selftests. Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20250710-kvm-selftests-eventfd-config-v1-1-78c276e4b80f@kernel.org Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/config | 1 + 1 file changed, 1 insertion(+) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/config b/tools/testing/selftests/kvm/config index 8835fed09e9f..96d874b239eb 100644 --- a/tools/testing/selftests/kvm/config +++ b/tools/testing/selftests/kvm/config @@ -1,5 +1,6 @@ CONFIG_KVM=y CONFIG_KVM_INTEL=y CONFIG_KVM_AMD=y +CONFIG_EVENTFD=y CONFIG_USERFAULTFD=y CONFIG_IDLE_PAGE_TRACKING=y -- cgit v1.2.3