From a51abbbf25317c07cb00b40ae7d04a209d2a3d54 Mon Sep 17 00:00:00 2001 From: Michal Luczaj Date: Thu, 13 Oct 2022 21:12:33 +0000 Subject: KVM: selftests: Add tests in xen_shinfo_test to detect lock races Tests for races between shinfo_cache (de)activation and hypercall+ioctl() processing. KVM has had bugs where activating the shared info cache multiple times and/or with concurrent users results in lock corruption, NULL pointer dereferences, and other fun. For the timer injection testcase (#22), re-arm the timer until the IRQ is successfully injected. If the timer expires while the shared info is deactivated (invalid), KVM will drop the event. Signed-off-by: Michal Luczaj Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Message-Id: <20221013211234.1318131-16-seanjc@google.com> Signed-off-by: Paolo Bonzini --- .../testing/selftests/kvm/x86_64/xen_shinfo_test.c | 140 +++++++++++++++++++++ 1 file changed, 140 insertions(+) (limited to 'tools/testing/selftests/kvm') diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c index 8a5cb800f50e..caa3f5ab9e10 100644 --- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c +++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c @@ -15,9 +15,13 @@ #include #include #include +#include #include +/* Defined in include/linux/kvm_types.h */ +#define GPA_INVALID (~(ulong)0) + #define SHINFO_REGION_GVA 0xc0000000ULL #define SHINFO_REGION_GPA 0xc0000000ULL #define SHINFO_REGION_SLOT 10 @@ -44,6 +48,8 @@ #define MIN_STEAL_TIME 50000 +#define SHINFO_RACE_TIMEOUT 2 /* seconds */ + #define __HYPERVISOR_set_timer_op 15 #define __HYPERVISOR_sched_op 29 #define __HYPERVISOR_event_channel_op 32 @@ -148,6 +154,7 @@ static void guest_wait_for_irq(void) static void guest_code(void) { struct vcpu_runstate_info *rs = (void *)RUNSTATE_VADDR; + int i; __asm__ __volatile__( "sti\n" @@ -325,6 +332,49 @@ static void guest_code(void) guest_wait_for_irq(); GUEST_SYNC(21); + /* Racing host ioctls */ + + guest_wait_for_irq(); + + GUEST_SYNC(22); + /* Racing vmcall against host ioctl */ + + ports[0] = 0; + + p = (struct sched_poll) { + .ports = ports, + .nr_ports = 1, + .timeout = 0 + }; + +wait_for_timer: + /* + * Poll for a timer wake event while the worker thread is mucking with + * the shared info. KVM XEN drops timer IRQs if the shared info is + * invalid when the timer expires. Arbitrarily poll 100 times before + * giving up and asking the VMM to re-arm the timer. 100 polls should + * consume enough time to beat on KVM without taking too long if the + * timer IRQ is dropped due to an invalid event channel. + */ + for (i = 0; i < 100 && !guest_saw_irq; i++) + asm volatile("vmcall" + : "=a" (rax) + : "a" (__HYPERVISOR_sched_op), + "D" (SCHEDOP_poll), + "S" (&p) + : "memory"); + + /* + * Re-send the timer IRQ if it was (likely) dropped due to the timer + * expiring while the event channel was invalid. + */ + if (!guest_saw_irq) { + GUEST_SYNC(23); + goto wait_for_timer; + } + guest_saw_irq = false; + + GUEST_SYNC(24); } static int cmp_timespec(struct timespec *a, struct timespec *b) @@ -352,11 +402,36 @@ static void handle_alrm(int sig) TEST_FAIL("IRQ delivery timed out"); } +static void *juggle_shinfo_state(void *arg) +{ + struct kvm_vm *vm = (struct kvm_vm *)arg; + + struct kvm_xen_hvm_attr cache_init = { + .type = KVM_XEN_ATTR_TYPE_SHARED_INFO, + .u.shared_info.gfn = SHINFO_REGION_GPA / PAGE_SIZE + }; + + struct kvm_xen_hvm_attr cache_destroy = { + .type = KVM_XEN_ATTR_TYPE_SHARED_INFO, + .u.shared_info.gfn = GPA_INVALID + }; + + for (;;) { + __vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &cache_init); + __vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &cache_destroy); + pthread_testcancel(); + }; + + return NULL; +} + int main(int argc, char *argv[]) { struct timespec min_ts, max_ts, vm_ts; struct kvm_vm *vm; + pthread_t thread; bool verbose; + int ret; verbose = argc > 1 && (!strncmp(argv[1], "-v", 3) || !strncmp(argv[1], "--verbose", 10)); @@ -785,6 +860,71 @@ int main(int argc, char *argv[]) case 21: TEST_ASSERT(!evtchn_irq_expected, "Expected event channel IRQ but it didn't happen"); + alarm(0); + + if (verbose) + printf("Testing shinfo lock corruption (KVM_XEN_HVM_EVTCHN_SEND)\n"); + + ret = pthread_create(&thread, NULL, &juggle_shinfo_state, (void *)vm); + TEST_ASSERT(ret == 0, "pthread_create() failed: %s", strerror(ret)); + + struct kvm_irq_routing_xen_evtchn uxe = { + .port = 1, + .vcpu = vcpu->id, + .priority = KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL + }; + + evtchn_irq_expected = true; + for (time_t t = time(NULL) + SHINFO_RACE_TIMEOUT; time(NULL) < t;) + __vm_ioctl(vm, KVM_XEN_HVM_EVTCHN_SEND, &uxe); + break; + + case 22: + TEST_ASSERT(!evtchn_irq_expected, + "Expected event channel IRQ but it didn't happen"); + + if (verbose) + printf("Testing shinfo lock corruption (SCHEDOP_poll)\n"); + + shinfo->evtchn_pending[0] = 1; + + evtchn_irq_expected = true; + tmr.u.timer.expires_ns = rs->state_entry_time + + SHINFO_RACE_TIMEOUT * 1000000000ULL; + vcpu_ioctl(vcpu, KVM_XEN_VCPU_SET_ATTR, &tmr); + break; + + case 23: + /* + * Optional and possibly repeated sync point. + * Injecting the timer IRQ may fail if the + * shinfo is invalid when the timer expires. + * If the timer has expired but the IRQ hasn't + * been delivered, rearm the timer and retry. + */ + vcpu_ioctl(vcpu, KVM_XEN_VCPU_GET_ATTR, &tmr); + + /* Resume the guest if the timer is still pending. */ + if (tmr.u.timer.expires_ns) + break; + + /* All done if the IRQ was delivered. */ + if (!evtchn_irq_expected) + break; + + tmr.u.timer.expires_ns = rs->state_entry_time + + SHINFO_RACE_TIMEOUT * 1000000000ULL; + vcpu_ioctl(vcpu, KVM_XEN_VCPU_SET_ATTR, &tmr); + break; + case 24: + TEST_ASSERT(!evtchn_irq_expected, + "Expected event channel IRQ but it didn't happen"); + + ret = pthread_cancel(thread); + TEST_ASSERT(ret == 0, "pthread_cancel() failed: %s", strerror(ret)); + + ret = pthread_join(thread, 0); + TEST_ASSERT(ret == 0, "pthread_join() failed: %s", strerror(ret)); goto done; case 0x20: -- cgit v1.2.3 From 5addaf530995ac203fa46efde0d1ded4c15ff98e Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 13 Oct 2022 21:12:34 +0000 Subject: KVM: selftests: Mark "guest_saw_irq" as volatile in xen_shinfo_test Tag "guest_saw_irq" as "volatile" to ensure that the compiler will never optimize away lookups. Relying on the compiler thinking that the flag is global and thus might change also works, but it's subtle, less robust, and looks like a bug at first glance, e.g. risks being "fixed" and breaking the test. Make the flag "static" as well since convincing the compiler it's global is no longer necessary. Alternatively, the flag could be accessed with {READ,WRITE}_ONCE(), but literally every access would need the wrappers, and eking out performance isn't exactly top priority for selftests. Signed-off-by: Sean Christopherson Message-Id: <20221013211234.1318131-17-seanjc@google.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/testing/selftests/kvm') diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c index caa3f5ab9e10..2a5727188c8d 100644 --- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c +++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c @@ -132,7 +132,7 @@ struct { struct kvm_irq_routing_entry entries[2]; } irq_routes; -bool guest_saw_irq; +static volatile bool guest_saw_irq; static void evtchn_handler(struct ex_regs *regs) { -- cgit v1.2.3 From fc6392d51d4810e4b611ef7dabd594756e5a2406 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Thu, 3 Nov 2022 16:13:47 +0200 Subject: KVM: selftests: move idt_entry to header struct idt_entry will be used for a test which will break IDT on purpose. Signed-off-by: Maxim Levitsky Message-Id: <20221103141351.50662-6-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/include/x86_64/processor.h | 13 +++++++++++++ tools/testing/selftests/kvm/lib/x86_64/processor.c | 13 ------------- 2 files changed, 13 insertions(+), 13 deletions(-) (limited to 'tools/testing/selftests/kvm') diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h index e8ca0d8a6a7e..5da0c5e2a7af 100644 --- a/tools/testing/selftests/kvm/include/x86_64/processor.h +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h @@ -748,6 +748,19 @@ struct ex_regs { uint64_t rflags; }; +struct idt_entry { + uint16_t offset0; + uint16_t selector; + uint16_t ist : 3; + uint16_t : 5; + uint16_t type : 4; + uint16_t : 1; + uint16_t dpl : 2; + uint16_t p : 1; + uint16_t offset1; + uint32_t offset2; uint32_t reserved; +}; + void vm_init_descriptor_tables(struct kvm_vm *vm); void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu); void vm_install_exception_handler(struct kvm_vm *vm, int vector, diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c index 39c4409ef56a..41c1c73c464d 100644 --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c @@ -1074,19 +1074,6 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits) } } -struct idt_entry { - uint16_t offset0; - uint16_t selector; - uint16_t ist : 3; - uint16_t : 5; - uint16_t type : 4; - uint16_t : 1; - uint16_t dpl : 2; - uint16_t p : 1; - uint16_t offset1; - uint32_t offset2; uint32_t reserved; -}; - static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr, int dpl, unsigned short selector) { -- cgit v1.2.3 From 0bd2d3f48704d9d00c29fa97fb80de012af87a0a Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Thu, 3 Nov 2022 16:13:48 +0200 Subject: kvm: selftests: add svm nested shutdown test Add test that tests that on SVM if L1 doesn't intercept SHUTDOWN, then L2 crashes L1 and doesn't crash L2 Signed-off-by: Maxim Levitsky Message-Id: <20221103141351.50662-7-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../kvm/x86_64/svm_nested_shutdown_test.c | 67 ++++++++++++++++++++++ 3 files changed, 69 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/svm_nested_shutdown_test.c (limited to 'tools/testing/selftests/kvm') diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index 2f0d705db9db..05d980fb083d 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -41,6 +41,7 @@ /x86_64/svm_vmcall_test /x86_64/svm_int_ctl_test /x86_64/svm_nested_soft_inject_test +/x86_64/svm_nested_shutdown_test /x86_64/sync_regs_test /x86_64/tsc_msrs_test /x86_64/tsc_scaling_sync diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 0172eb6cb6ee..4a2caef2c939 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -101,6 +101,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/state_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test TEST_GEN_PROGS_x86_64 += x86_64/svm_int_ctl_test +TEST_GEN_PROGS_x86_64 += x86_64/svm_nested_shutdown_test TEST_GEN_PROGS_x86_64 += x86_64/svm_nested_soft_inject_test TEST_GEN_PROGS_x86_64 += x86_64/tsc_scaling_sync TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test diff --git a/tools/testing/selftests/kvm/x86_64/svm_nested_shutdown_test.c b/tools/testing/selftests/kvm/x86_64/svm_nested_shutdown_test.c new file mode 100644 index 000000000000..e73fcdef47bb --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/svm_nested_shutdown_test.c @@ -0,0 +1,67 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * svm_nested_shutdown_test + * + * Copyright (C) 2022, Red Hat, Inc. + * + * Nested SVM testing: test that unintercepted shutdown in L2 doesn't crash the host + */ + +#include "test_util.h" +#include "kvm_util.h" +#include "processor.h" +#include "svm_util.h" + +static void l2_guest_code(struct svm_test_data *svm) +{ + __asm__ __volatile__("ud2"); +} + +static void l1_guest_code(struct svm_test_data *svm, struct idt_entry *idt) +{ + #define L2_GUEST_STACK_SIZE 64 + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + struct vmcb *vmcb = svm->vmcb; + + generic_svm_setup(svm, l2_guest_code, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + vmcb->control.intercept &= ~(BIT(INTERCEPT_SHUTDOWN)); + + idt[6].p = 0; // #UD is intercepted but its injection will cause #NP + idt[11].p = 0; // #NP is not intercepted and will cause another + // #NP that will be converted to #DF + idt[8].p = 0; // #DF will cause #NP which will cause SHUTDOWN + + run_guest(vmcb, svm->vmcb_gpa); + + /* should not reach here */ + GUEST_ASSERT(0); +} + +int main(int argc, char *argv[]) +{ + struct kvm_vcpu *vcpu; + struct kvm_run *run; + vm_vaddr_t svm_gva; + struct kvm_vm *vm; + + TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM)); + + vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code); + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(vcpu); + + vcpu_alloc_svm(vm, &svm_gva); + + vcpu_args_set(vcpu, 2, svm_gva, vm->idt); + run = vcpu->run; + + vcpu_run(vcpu); + TEST_ASSERT(run->exit_reason == KVM_EXIT_SHUTDOWN, + "Got exit_reason other than KVM_EXIT_SHUTDOWN: %u (%s)\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + + kvm_vm_free(vm); +} -- cgit v1.2.3 From 8357b9e19bbb5c9ce671c7b6cb93e03fc0fe4016 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Thu, 3 Nov 2022 16:13:50 +0200 Subject: KVM: selftests: add svm part to triple_fault_test Add a SVM implementation to triple_fault_test to test that emulated/injected shutdown works. Since instead of the VMX, the SVM allows the hypervisor to avoid intercepting shutdown in guest, don't intercept shutdown to test that KVM suports this correctly. Signed-off-by: Maxim Levitsky Message-Id: <20221103141351.50662-9-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- .../selftests/kvm/x86_64/triple_fault_event_test.c | 73 +++++++++++++++++----- 1 file changed, 56 insertions(+), 17 deletions(-) (limited to 'tools/testing/selftests/kvm') diff --git a/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c b/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c index 70b44f0b52fe..ead5d878a71c 100644 --- a/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c +++ b/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c @@ -3,6 +3,7 @@ #include "kvm_util.h" #include "processor.h" #include "vmx.h" +#include "svm_util.h" #include #include @@ -20,10 +21,11 @@ static void l2_guest_code(void) : : [port] "d" (ARBITRARY_IO_PORT) : "rax"); } -void l1_guest_code(struct vmx_pages *vmx) -{ #define L2_GUEST_STACK_SIZE 64 - unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; +unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + +void l1_guest_code_vmx(struct vmx_pages *vmx) +{ GUEST_ASSERT(vmx->vmcs_gpa); GUEST_ASSERT(prepare_for_vmx_operation(vmx)); @@ -38,24 +40,53 @@ void l1_guest_code(struct vmx_pages *vmx) GUEST_DONE(); } +void l1_guest_code_svm(struct svm_test_data *svm) +{ + struct vmcb *vmcb = svm->vmcb; + + generic_svm_setup(svm, l2_guest_code, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + /* don't intercept shutdown to test the case of SVM allowing to do so */ + vmcb->control.intercept &= ~(BIT(INTERCEPT_SHUTDOWN)); + + run_guest(vmcb, svm->vmcb_gpa); + + /* should not reach here, L1 should crash */ + GUEST_ASSERT(0); +} + int main(void) { struct kvm_vcpu *vcpu; struct kvm_run *run; struct kvm_vcpu_events events; - vm_vaddr_t vmx_pages_gva; struct ucall uc; - TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX)); + bool has_vmx = kvm_cpu_has(X86_FEATURE_VMX); + bool has_svm = kvm_cpu_has(X86_FEATURE_SVM); + + TEST_REQUIRE(has_vmx || has_svm); TEST_REQUIRE(kvm_has_cap(KVM_CAP_X86_TRIPLE_FAULT_EVENT)); - vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code); - vm_enable_cap(vm, KVM_CAP_X86_TRIPLE_FAULT_EVENT, 1); + if (has_vmx) { + vm_vaddr_t vmx_pages_gva; + + vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code_vmx); + vcpu_alloc_vmx(vm, &vmx_pages_gva); + vcpu_args_set(vcpu, 1, vmx_pages_gva); + } else { + vm_vaddr_t svm_gva; + + vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code_svm); + vcpu_alloc_svm(vm, &svm_gva); + vcpu_args_set(vcpu, 1, svm_gva); + } + + vm_enable_cap(vm, KVM_CAP_X86_TRIPLE_FAULT_EVENT, 1); run = vcpu->run; - vcpu_alloc_vmx(vm, &vmx_pages_gva); - vcpu_args_set(vcpu, 1, vmx_pages_gva); vcpu_run(vcpu); TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, @@ -78,13 +109,21 @@ int main(void) "No triple fault pending"); vcpu_run(vcpu); - switch (get_ucall(vcpu, &uc)) { - case UCALL_DONE: - break; - case UCALL_ABORT: - REPORT_GUEST_ASSERT(uc); - default: - TEST_FAIL("Unexpected ucall: %lu", uc.cmd); - } + if (has_svm) { + TEST_ASSERT(run->exit_reason == KVM_EXIT_SHUTDOWN, + "Got exit_reason other than KVM_EXIT_SHUTDOWN: %u (%s)\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + } else { + switch (get_ucall(vcpu, &uc)) { + case UCALL_DONE: + break; + case UCALL_ABORT: + REPORT_GUEST_ASSERT(uc); + default: + TEST_FAIL("Unexpected ucall: %lu", uc.cmd); + } + } + return 0; } -- cgit v1.2.3