diff options
Diffstat (limited to 'tools/testing/selftests/kvm/x86_64/sync_regs_test.c')
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/sync_regs_test.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c index 2da89fdc2471..00965ba33f73 100644 --- a/tools/testing/selftests/kvm/x86_64/sync_regs_test.c +++ b/tools/testing/selftests/kvm/x86_64/sync_regs_test.c @@ -15,6 +15,7 @@ #include <stdlib.h> #include <string.h> #include <sys/ioctl.h> +#include <pthread.h> #include "test_util.h" #include "kvm_util.h" @@ -80,6 +81,133 @@ static void compare_vcpu_events(struct kvm_vcpu_events *left, #define TEST_SYNC_FIELDS (KVM_SYNC_X86_REGS|KVM_SYNC_X86_SREGS|KVM_SYNC_X86_EVENTS) #define INVALID_SYNC_FIELD 0x80000000 +/* + * Set an exception as pending *and* injected while KVM is processing events. + * KVM is supposed to ignore/drop pending exceptions if userspace is also + * requesting that an exception be injected. + */ +static void *race_events_inj_pen(void *arg) +{ + struct kvm_run *run = (struct kvm_run *)arg; + struct kvm_vcpu_events *events = &run->s.regs.events; + + WRITE_ONCE(events->exception.nr, UD_VECTOR); + + for (;;) { + WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_EVENTS); + WRITE_ONCE(events->flags, 0); + WRITE_ONCE(events->exception.injected, 1); + WRITE_ONCE(events->exception.pending, 1); + + pthread_testcancel(); + } + + return NULL; +} + +/* + * Set an invalid exception vector while KVM is processing events. KVM is + * supposed to reject any vector >= 32, as well as NMIs (vector 2). + */ +static void *race_events_exc(void *arg) +{ + struct kvm_run *run = (struct kvm_run *)arg; + struct kvm_vcpu_events *events = &run->s.regs.events; + + for (;;) { + WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_EVENTS); + WRITE_ONCE(events->flags, 0); + WRITE_ONCE(events->exception.nr, UD_VECTOR); + WRITE_ONCE(events->exception.pending, 1); + WRITE_ONCE(events->exception.nr, 255); + + pthread_testcancel(); + } + + return NULL; +} + +/* + * Toggle CR4.PAE while KVM is processing SREGS, EFER.LME=1 with CR4.PAE=0 is + * illegal, and KVM's MMU heavily relies on vCPU state being valid. + */ +static noinline void *race_sregs_cr4(void *arg) +{ + struct kvm_run *run = (struct kvm_run *)arg; + __u64 *cr4 = &run->s.regs.sregs.cr4; + __u64 pae_enabled = *cr4; + __u64 pae_disabled = *cr4 & ~X86_CR4_PAE; + + for (;;) { + WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_SREGS); + WRITE_ONCE(*cr4, pae_enabled); + asm volatile(".rept 512\n\t" + "nop\n\t" + ".endr"); + WRITE_ONCE(*cr4, pae_disabled); + + pthread_testcancel(); + } + + return NULL; +} + +static void race_sync_regs(void *racer) +{ + const time_t TIMEOUT = 2; /* seconds, roughly */ + struct kvm_x86_state *state; + struct kvm_translation tr; + struct kvm_vcpu *vcpu; + struct kvm_run *run; + struct kvm_vm *vm; + pthread_t thread; + time_t t; + + vm = vm_create_with_one_vcpu(&vcpu, guest_code); + run = vcpu->run; + + run->kvm_valid_regs = KVM_SYNC_X86_SREGS; + vcpu_run(vcpu); + run->kvm_valid_regs = 0; + + /* Save state *before* spawning the thread that mucks with vCPU state. */ + state = vcpu_save_state(vcpu); + + /* + * Selftests run 64-bit guests by default, both EFER.LME and CR4.PAE + * should already be set in guest state. + */ + TEST_ASSERT((run->s.regs.sregs.cr4 & X86_CR4_PAE) && + (run->s.regs.sregs.efer & EFER_LME), + "vCPU should be in long mode, CR4.PAE=%d, EFER.LME=%d", + !!(run->s.regs.sregs.cr4 & X86_CR4_PAE), + !!(run->s.regs.sregs.efer & EFER_LME)); + + TEST_ASSERT_EQ(pthread_create(&thread, NULL, racer, (void *)run), 0); + + for (t = time(NULL) + TIMEOUT; time(NULL) < t;) { + /* + * Reload known good state if the vCPU triple faults, e.g. due + * to the unhandled #GPs being injected. VMX preserves state + * on shutdown, but SVM synthesizes an INIT as the VMCB state + * is architecturally undefined on triple fault. + */ + if (!__vcpu_run(vcpu) && run->exit_reason == KVM_EXIT_SHUTDOWN) + vcpu_load_state(vcpu, state); + + if (racer == race_sregs_cr4) { + tr = (struct kvm_translation) { .linear_address = 0 }; + __vcpu_ioctl(vcpu, KVM_TRANSLATE, &tr); + } + } + + TEST_ASSERT_EQ(pthread_cancel(thread), 0); + TEST_ASSERT_EQ(pthread_join(thread, NULL), 0); + + kvm_x86_state_cleanup(state); + kvm_vm_free(vm); +} + int main(int argc, char *argv[]) { struct kvm_vcpu *vcpu; @@ -218,5 +346,9 @@ int main(int argc, char *argv[]) kvm_vm_free(vm); + race_sync_regs(race_sregs_cr4); + race_sync_regs(race_events_exc); + race_sync_regs(race_events_inj_pen); + return 0; } |