| Message ID | 1619161883-5963-1-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/xen: Take srcu lock when accessing kvm_memslots() | expand |
On 23/04/21 09:11, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > kvm_memslots() will be called by kvm_write_guest_offset_cached() so > take the srcu lock. > > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Good catch. But I would pull it from kvm_steal_time_set_preempted to kvm_arch_vcpu_put instead. Paolo > --- > arch/x86/kvm/xen.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c > index ae17250..d0df782 100644 > --- a/arch/x86/kvm/xen.c > +++ b/arch/x86/kvm/xen.c > @@ -96,6 +96,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > struct kvm_vcpu_xen *vx = &v->arch.xen; > uint64_t state_entry_time; > unsigned int offset; > + int idx; > > kvm_xen_update_runstate(v, state); > > @@ -133,10 +134,16 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > BUILD_BUG_ON(sizeof(((struct compat_vcpu_runstate_info *)0)->state_entry_time) != > sizeof(state_entry_time)); > > + /* > + * Take the srcu lock as memslots will be accessed to check the gfn > + * cache generation against the memslots generation. > + */ > + idx = srcu_read_lock(&v->kvm->srcu); > + > if (kvm_write_guest_offset_cached(v->kvm, &v->arch.xen.runstate_cache, > &state_entry_time, offset, > sizeof(state_entry_time))) > - return; > + goto out; > smp_wmb(); > > /* > @@ -154,7 +161,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > &vx->current_runstate, > offsetof(struct vcpu_runstate_info, state), > sizeof(vx->current_runstate))) > - return; > + goto out; > > /* > * Write the actual runstate times immediately after the > @@ -173,7 +180,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > &vx->runstate_times[0], > offset + sizeof(u64), > sizeof(vx->runstate_times))) > - return; > + goto out; > > smp_wmb(); > > @@ -186,7 +193,10 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) > if (kvm_write_guest_offset_cached(v->kvm, &v->arch.xen.runstate_cache, > &state_entry_time, offset, > sizeof(state_entry_time))) > - return; > + goto out; > + > +out: > + srcu_read_unlock(&v->kvm->srcu, idx); > } > > int __kvm_xen_has_interrupt(struct kvm_vcpu *v) >
On Fri, 23 Apr 2021 at 16:13, Paolo Bonzini <pbonzini@redhat.com> wrote: > > On 23/04/21 09:11, Wanpeng Li wrote: > > From: Wanpeng Li <wanpengli@tencent.com> > > > > kvm_memslots() will be called by kvm_write_guest_offset_cached() so > > take the srcu lock. > > > > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > > Good catch. But I would pull it from kvm_steal_time_set_preempted to > kvm_arch_vcpu_put instead. Will do. :) Wanpeng
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index ae17250..d0df782 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -96,6 +96,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) struct kvm_vcpu_xen *vx = &v->arch.xen; uint64_t state_entry_time; unsigned int offset; + int idx; kvm_xen_update_runstate(v, state); @@ -133,10 +134,16 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) BUILD_BUG_ON(sizeof(((struct compat_vcpu_runstate_info *)0)->state_entry_time) != sizeof(state_entry_time)); + /* + * Take the srcu lock as memslots will be accessed to check the gfn + * cache generation against the memslots generation. + */ + idx = srcu_read_lock(&v->kvm->srcu); + if (kvm_write_guest_offset_cached(v->kvm, &v->arch.xen.runstate_cache, &state_entry_time, offset, sizeof(state_entry_time))) - return; + goto out; smp_wmb(); /* @@ -154,7 +161,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) &vx->current_runstate, offsetof(struct vcpu_runstate_info, state), sizeof(vx->current_runstate))) - return; + goto out; /* * Write the actual runstate times immediately after the @@ -173,7 +180,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) &vx->runstate_times[0], offset + sizeof(u64), sizeof(vx->runstate_times))) - return; + goto out; smp_wmb(); @@ -186,7 +193,10 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) if (kvm_write_guest_offset_cached(v->kvm, &v->arch.xen.runstate_cache, &state_entry_time, offset, sizeof(state_entry_time))) - return; + goto out; + +out: + srcu_read_unlock(&v->kvm->srcu, idx); } int __kvm_xen_has_interrupt(struct kvm_vcpu *v)