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authorPaul Mackerras <paulus@samba.org>2013-11-16 17:46:05 +1100
committerAlexander Graf <agraf@suse.de>2013-11-18 22:41:20 +0100
commitc9438092cae4a5bdbd146ca1385e85dcd6e847f8 (patch)
treed31a775f83754d6226604b941034c866c2257bff /arch
parentbf3d32e1156c36c88b75960fd2e5457d5d75620b (diff)
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KVM: PPC: Book3S HV: Take SRCU read lock around kvm_read_guest() call
Running a kernel with CONFIG_PROVE_RCU=y yields the following diagnostic: =============================== [ INFO: suspicious RCU usage. ] 3.12.0-rc5-kvm+ #9 Not tainted ------------------------------- include/linux/kvm_host.h:473 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 1 lock held by qemu-system-ppc/4831: stack backtrace: CPU: 28 PID: 4831 Comm: qemu-system-ppc Not tainted 3.12.0-rc5-kvm+ #9 Call Trace: [c000000be462b2a0] [c00000000001644c] .show_stack+0x7c/0x1f0 (unreliable) [c000000be462b370] [c000000000ad57c0] .dump_stack+0x88/0xb4 [c000000be462b3f0] [c0000000001315e8] .lockdep_rcu_suspicious+0x138/0x180 [c000000be462b480] [c00000000007862c] .gfn_to_memslot+0x13c/0x170 [c000000be462b510] [c00000000007d384] .gfn_to_hva_prot+0x24/0x90 [c000000be462b5a0] [c00000000007d420] .kvm_read_guest_page+0x30/0xd0 [c000000be462b630] [c00000000007d528] .kvm_read_guest+0x68/0x110 [c000000be462b6e0] [c000000000084594] .kvmppc_rtas_hcall+0x34/0x180 [c000000be462b7d0] [c000000000097934] .kvmppc_pseries_do_hcall+0x74/0x830 [c000000be462b880] [c0000000000990e8] .kvmppc_vcpu_run_hv+0xff8/0x15a0 [c000000be462b9e0] [c0000000000839cc] .kvmppc_vcpu_run+0x2c/0x40 [c000000be462ba50] [c0000000000810b4] .kvm_arch_vcpu_ioctl_run+0x54/0x1b0 [c000000be462bae0] [c00000000007b508] .kvm_vcpu_ioctl+0x478/0x730 [c000000be462bca0] [c00000000025532c] .do_vfs_ioctl+0x4dc/0x7a0 [c000000be462bd80] [c0000000002556b4] .SyS_ioctl+0xc4/0xe0 [c000000be462be30] [c000000000009ee4] syscall_exit+0x0/0x98 To fix this, we take the SRCU read lock around the kvmppc_rtas_hcall() call. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kvm/book3s_hv.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 31d9cfb64a23..b51d5db78068 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -591,7 +591,9 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
if (list_empty(&vcpu->kvm->arch.rtas_tokens))
return RESUME_HOST;
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
rc = kvmppc_rtas_hcall(vcpu);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
if (rc == -ENOENT)
return RESUME_HOST;