From 4f899147424a189b0ad1fdd6f35784ed5a642e83 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Mon, 10 Jul 2017 13:35:48 +0200 Subject: [PATCH] KVM: s390: take srcu lock when getting/setting storage keys The following warning was triggered by missing srcu locks around the storage key handling functions. ============================= WARNING: suspicious RCU usage 4.12.0+ #56 Not tainted ----------------------------- ./include/linux/kvm_host.h:572 suspicious rcu_dereference_check() usage! rcu_scheduler_active = 2, debug_locks = 1 1 lock held by live_migration/4936: #0: (&mm->mmap_sem){++++++}, at: [<0000000000141be0>] kvm_arch_vm_ioctl+0x6b8/0x22d0 CPU: 8 PID: 4936 Comm: live_migration Not tainted 4.12.0+ #56 Hardware name: IBM 2964 NC9 704 (LPAR) Call Trace: ([<000000000011378a>] show_stack+0xea/0xf0) [<000000000055cc4c>] dump_stack+0x94/0xd8 [<000000000012ee70>] gfn_to_memslot+0x1a0/0x1b8 [<0000000000130b76>] gfn_to_hva+0x2e/0x48 [<0000000000141c3c>] kvm_arch_vm_ioctl+0x714/0x22d0 [<000000000013306c>] kvm_vm_ioctl+0x11c/0x7b8 [<000000000037e2c0>] do_vfs_ioctl+0xa8/0x6c8 [<000000000037e984>] SyS_ioctl+0xa4/0xb8 [<00000000008b20a4>] system_call+0xc4/0x27c 1 lock held by live_migration/4936: #0: (&mm->mmap_sem){++++++}, at: [<0000000000141be0>] kvm_arch_vm_ioctl+0x6b8/0x22d0 Signed-off-by: Christian Borntraeger Reviewed-by: Pierre Morel --- arch/s390/kvm/kvm-s390.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 3f2884e99ed4..af09d3437631 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1324,7 +1324,7 @@ static long kvm_s390_get_skeys(struct kvm *kvm, struct kvm_s390_skeys *args) { uint8_t *keys; uint64_t hva; - int i, r = 0; + int srcu_idx, i, r = 0; if (args->flags != 0) return -EINVAL; @@ -1342,6 +1342,7 @@ static long kvm_s390_get_skeys(struct kvm *kvm, struct kvm_s390_skeys *args) return -ENOMEM; down_read(¤t->mm->mmap_sem); + srcu_idx = srcu_read_lock(&kvm->srcu); for (i = 0; i < args->count; i++) { hva = gfn_to_hva(kvm, args->start_gfn + i); if (kvm_is_error_hva(hva)) { @@ -1353,6 +1354,7 @@ static long kvm_s390_get_skeys(struct kvm *kvm, struct kvm_s390_skeys *args) if (r) break; } + srcu_read_unlock(&kvm->srcu, srcu_idx); up_read(¤t->mm->mmap_sem); if (!r) { @@ -1370,7 +1372,7 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args) { uint8_t *keys; uint64_t hva; - int i, r = 0; + int srcu_idx, i, r = 0; if (args->flags != 0) return -EINVAL; @@ -1396,6 +1398,7 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args) goto out; down_read(¤t->mm->mmap_sem); + srcu_idx = srcu_read_lock(&kvm->srcu); for (i = 0; i < args->count; i++) { hva = gfn_to_hva(kvm, args->start_gfn + i); if (kvm_is_error_hva(hva)) { @@ -1413,6 +1416,7 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args) if (r) break; } + srcu_read_unlock(&kvm->srcu, srcu_idx); up_read(¤t->mm->mmap_sem); out: kvfree(keys); -- 2.20.1