Commit 2ae41db2 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: do not use sigtimedwait to catch SIGBUS 



Call kvm_on_sigbus_vcpu asynchronously from the VCPU thread.
Information for the SIGBUS can be stored in thread-local variables
and processed later in kvm_cpu_exec.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4d39892c

cpus.c

+13 −18
Original line number Diff line number Diff line
@@ -926,10 +926,18 @@ static void sigbus_handler(int n, siginfo_t *siginfo, void *ctx) 
        sigbus_reraise();

    }



    if (current_cpu) {

        /* Called asynchronously in VCPU thread.  */

        if (kvm_on_sigbus_vcpu(current_cpu, siginfo->si_code, siginfo->si_addr)) {

            sigbus_reraise();

        }

    } else {

        /* Called synchronously (via signalfd) in main thread.  */

        if (kvm_on_sigbus(siginfo->si_code, siginfo->si_addr)) {

            sigbus_reraise();

        }

    }

}



static void qemu_init_sigbus(void)

{
@@ -958,8 +966,9 @@ static void qemu_kvm_init_cpu_signals(CPUState *cpu) 
    sigaction(SIG_IPI, &sigact, NULL);



    pthread_sigmask(SIG_BLOCK, NULL, &set);

    sigdelset(&set, SIG_IPI);

    sigdelset(&set, SIGBUS);

    pthread_sigmask(SIG_SETMASK, &set, NULL);

    sigdelset(&set, SIG_IPI);

    r = kvm_set_signal_mask(cpu, &set);

    if (r) {

        fprintf(stderr, "kvm_set_signal_mask: %s\n", strerror(-r));
@@ -977,7 +986,6 @@ static void qemu_kvm_eat_signals(CPUState *cpu) 


    sigemptyset(&waitset);

    sigaddset(&waitset, SIG_IPI);

    sigaddset(&waitset, SIGBUS);



    do {

        r = sigtimedwait(&waitset, &siginfo, &ts);
@@ -986,25 +994,12 @@ static void qemu_kvm_eat_signals(CPUState *cpu) 
            exit(1);

        }



        switch (r) {

        case SIGBUS:

            if (siginfo.si_code != BUS_MCEERR_AO && siginfo.si_code != BUS_MCEERR_AR) {

                sigbus_reraise();

            }

            if (kvm_on_sigbus_vcpu(cpu, siginfo.si_code, siginfo.si_addr)) {

                sigbus_reraise();

            }

            break;

        default:

            break;

        }



        r = sigpending(&chkset);

        if (r == -1) {

            perror("sigpending");

            exit(1);

        }

    } while (sigismember(&chkset, SIG_IPI) || sigismember(&chkset, SIGBUS));

    } while (sigismember(&chkset, SIG_IPI));

}

#else /* !CONFIG_LINUX */

static void qemu_init_sigbus(void)

include/sysemu/kvm.h

+4 −1
Original line number Diff line number Diff line
@@ -357,7 +357,10 @@ bool kvm_vcpu_id_is_valid(int vcpu_id); 
/* Returns VCPU ID to be used on KVM_CREATE_VCPU ioctl() */

unsigned long kvm_arch_vcpu_id(CPUState *cpu);



int kvm_arch_on_sigbus_vcpu(CPUState *cpu, int code, void *addr);

#ifdef TARGET_I386

#define KVM_HAVE_MCE_INJECTION 1

void kvm_arch_on_sigbus_vcpu(CPUState *cpu, int code, void *addr);

#endif



void kvm_arch_init_irq_routing(KVMState *s);

kvm-all.c

+34 −1
Original line number Diff line number Diff line
@@ -1893,6 +1893,12 @@ void kvm_cpu_synchronize_post_init(CPUState *cpu) 
    run_on_cpu(cpu, do_kvm_cpu_synchronize_post_init, RUN_ON_CPU_NULL);

}



#ifdef KVM_HAVE_MCE_INJECTION

static __thread void *pending_sigbus_addr;

static __thread int pending_sigbus_code;

static __thread bool have_sigbus_pending;

#endif



int kvm_cpu_exec(CPUState *cpu)

{

    struct kvm_run *run = cpu->kvm_run;
@@ -1930,6 +1936,16 @@ int kvm_cpu_exec(CPUState *cpu) 


        attrs = kvm_arch_post_run(cpu, run);



#ifdef KVM_HAVE_MCE_INJECTION

        if (unlikely(have_sigbus_pending)) {

            qemu_mutex_lock_iothread();

            kvm_arch_on_sigbus_vcpu(cpu, pending_sigbus_code,

                                    pending_sigbus_addr);

            have_sigbus_pending = false;

            qemu_mutex_unlock_iothread();

        }

#endif



        if (run_ret < 0) {

            if (run_ret == -EINTR || run_ret == -EAGAIN) {

                DPRINTF("io window exit\n");
@@ -2392,13 +2408,27 @@ int kvm_set_signal_mask(CPUState *cpu, const sigset_t *sigset) 
    return r;

}



/* Called asynchronously in VCPU thread.  */

int kvm_on_sigbus_vcpu(CPUState *cpu, int code, void *addr)

{

    return kvm_arch_on_sigbus_vcpu(cpu, code, addr);

#ifdef KVM_HAVE_MCE_INJECTION

    if (have_sigbus_pending) {

        return 1;

    }

    have_sigbus_pending = true;

    pending_sigbus_addr = addr;

    pending_sigbus_code = code;

    atomic_set(&cpu->exit_request, 1);

    return 0;

#else

    return 1;

#endif

}



/* Called synchronously (via signalfd) in main thread.  */

int kvm_on_sigbus(int code, void *addr)

{

#ifdef KVM_HAVE_MCE_INJECTION

    /* Action required MCE kills the process if SIGBUS is blocked.  Because

     * that's what happens in the I/O thread, where we handle MCE via signalfd,

     * we can only get action optional here.
@@ -2406,6 +2436,9 @@ int kvm_on_sigbus(int code, void *addr) 
    assert(code != BUS_MCEERR_AR);

    kvm_arch_on_sigbus_vcpu(first_cpu, code, addr);

    return 0;

#else

    return 1;

#endif

}



int kvm_create_device(KVMState *s, uint64_t type, bool test)

target/arm/kvm.c

+0 −5
Original line number Diff line number Diff line
@@ -560,11 +560,6 @@ int kvm_arch_process_async_events(CPUState *cs) 
    return 0;

}



int kvm_arch_on_sigbus_vcpu(CPUState *cs, int code, void *addr)

{

    return 1;

}



/* The #ifdef protections are until 32bit headers are imported and can

 * be removed once both 32 and 64 bit reach feature parity.

 */

target/i386/kvm.c

+2 −3
Original line number Diff line number Diff line
@@ -455,7 +455,7 @@ static void hardware_memory_error(void) 
    exit(1);

}



int kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void *addr)

void kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void *addr)

{

    X86CPU *cpu = X86_CPU(c);

    CPUX86State *env = &cpu->env;
@@ -475,7 +475,7 @@ int kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void *addr) 
            kvm_physical_memory_addr_from_host(c->kvm_state, addr, &paddr)) {

            kvm_hwpoison_page_add(ram_addr);

            kvm_mce_inject(cpu, paddr, code);

            return 0;

            return;

        }



        fprintf(stderr, "Hardware memory error for memory used by "
@@ -487,7 +487,6 @@ int kvm_arch_on_sigbus_vcpu(CPUState *c, int code, void *addr) 
    }



    /* Hope we are lucky for AO MCE */

    return 0;

}



static int kvm_inject_mce_oldstyle(X86CPU *cpu)