Commit 94ccff13 authored by thomas knych's avatar thomas knych Committed by Paolo Bonzini
Browse files

KVM: Retry KVM_CREATE_VM on EINTR 

Upstreaming this change from Android (https://android-review.googlesource.com/54211

).

On heavily loaded machines with many VM instances we see KVM_CREATE_VM
failing with EINTR on this path:

kvm_dev_ioctl_create_vm -> kvm_create_vm -> kvm_init_mmu_notifier -> mmu_notifier_register ->  do_mmu_notifier_register -> mm_take_all_locks

which checks if any signals have been raised while it was attaining locks
and returns EINTR.  Retrying the system call greatly improves reliability.

Cc: qemu-stable@nongnu.org
Signed-off-by: default avatarthomas knych <thomaswk@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2ba82852

kvm-all.c

+9 −3
Original line number Diff line number Diff line
@@ -1442,16 +1442,22 @@ int kvm_init(void) 
        nc++;

    }



    s->vmfd = kvm_ioctl(s, KVM_CREATE_VM, 0);

    if (s->vmfd < 0) {

    do {

        ret = kvm_ioctl(s, KVM_CREATE_VM, 0);

    } while (ret == -EINTR);



    if (ret < 0) {

        fprintf(stderr, "ioctl(KVM_CREATE_VM) failed: %d %s\n", -s->vmfd,

                strerror(-ret));



#ifdef TARGET_S390X

        fprintf(stderr, "Please add the 'switch_amode' kernel parameter to "

                        "your host kernel command line\n");

#endif

        ret = s->vmfd;

        goto err;

    }



    s->vmfd = ret;

    missing_cap = kvm_check_extension_list(s, kvm_required_capabilites);

    if (!missing_cap) {

        missing_cap =