On 23/04/21 09:11, Wanpeng Li wrote:
From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
kvm_memslots() will be called by kvm_write_guest_offset_cached() so
take the srcu lock.
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
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)
