From 94ccff133820552a859c0fb95e33a539e0b90a75 Mon Sep 17 00:00:00 2001 From: thomas knych Date: Thu, 9 Jan 2014 13:14:23 -0800 Subject: [PATCH] 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: thomas knych Signed-off-by: Paolo Bonzini --- kvm-all.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/kvm-all.c b/kvm-all.c index 393775459d..6df2ee1635 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -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 =