diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2015-09-21 07:46:55 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-09-25 10:31:22 +0200 |
| commit | 79a8059d244e99454e474902e4325ee9b50e9178 (patch) | |
| tree | 3af117f2aea8b144e407327e7a72ff5b2d72a1a5 | |
| parent | 5b6a7175bfe570857a85b5570857e7555eff2c3a (diff) | |
KVM: svm: do not call kvm_set_cr0 from init_vmcb
kvm_set_cr0 may want to call kvm_zap_gfn_range and thus access the
memslots array (SRCU protected). Using a mini SRCU critical section
is ugly, and adding it to kvm_arch_vcpu_create doesn't work because
the VMX vcpu_create callback calls synchronize_srcu.
Fixes this lockdep splat:
===============================
[ INFO: suspicious RCU usage. ]
4.3.0-rc1+ #1 Not tainted
-------------------------------
include/linux/kvm_host.h:488 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-i38/17000:
#0: (&(&kvm->mmu_lock)->rlock){+.+...}, at: kvm_zap_gfn_range+0x24/0x1a0 [kvm]
[...]
Call Trace:
dump_stack+0x4e/0x84
lockdep_rcu_suspicious+0xfd/0x130
kvm_zap_gfn_range+0x188/0x1a0 [kvm]
kvm_set_cr0+0xde/0x1e0 [kvm]
init_vmcb+0x760/0xad0 [kvm_amd]
svm_create_vcpu+0x197/0x250 [kvm_amd]
kvm_arch_vcpu_create+0x47/0x70 [kvm]
kvm_vm_ioctl+0x302/0x7e0 [kvm]
? __lock_is_held+0x51/0x70
? __fget+0x101/0x210
do_vfs_ioctl+0x2f4/0x560
? __fget_light+0x29/0x90
SyS_ioctl+0x4c/0x90
entry_SYSCALL_64_fastpath+0x16/0x73
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/svm.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 89173af53c84..94b7d15db3fc 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -202,6 +202,7 @@ module_param(npt, int, S_IRUGO); static int nested = true; module_param(nested, int, S_IRUGO); +static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0); static void svm_flush_tlb(struct kvm_vcpu *vcpu); static void svm_complete_interrupts(struct vcpu_svm *svm); @@ -1263,7 +1264,7 @@ static void init_vmcb(struct vcpu_svm *svm, bool init_event) * svm_set_cr0() sets PG and WP and clears NW and CD on save->cr0. * It also updates the guest-visible cr0 value. */ - (void)kvm_set_cr0(&svm->vcpu, X86_CR0_NW | X86_CR0_CD | X86_CR0_ET); + svm_set_cr0(&svm->vcpu, X86_CR0_NW | X86_CR0_CD | X86_CR0_ET); kvm_mmu_reset_context(&svm->vcpu); save->cr4 = X86_CR4_PAE; |