On 02/19/2016 07:51 PM, Paolo Bonzini wrote:
On 14/02/2016 12:31, Xiao Guangrong wrote:
+void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
+ int bytes)
+{
+ struct kvm_page_track_notifier_head *head;
+ struct kvm_page_track_notifier_node *n;
+ int idx;
+
+ head = &vcpu->kvm->arch.track_notifier_head;
Please check outside SRCU if the notifier list is empty. If so, there
is no need to do the (relatively) expensive srcu_read_lock/unlock.
Good to me. I will check it by calling hlist_empty() first before holding
the srcu read lock.
Paolo
+ idx = srcu_read_lock(&head->track_srcu);
+ hlist_for_each_entry_rcu(n, &head->track_notifier_list, node)
+ if (n->track_write)
+ n->track_write(vcpu, gpa, new, bytes);
+ srcu_read_unlock(&head->track_srcu, idx);
+}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e25ebb7..98019b6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4370,6 +4370,7 @@ int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
if (ret < 0)
return 0;
A kvm_vcpu_mark_page_dirty is missing here, isn't it? I can take care
of it, but it would be great if you double-checked this. If so, that
should be fixed in stable kernels too.
No. It's already been handled in emulator_write_phys() -> kvm_vcpu_write_guest()
-> kvm_vcpu_write_guest_page() -> __kvm_write_guest_page().
Can you add a kvm_vcpu_note_page_write(vcpu, gpa, val, bytes) function
that takes care of calling kvm_vcpu_mark_page_dirty, kvm_mmu_pte_write
and kvm_page_track-write?
After this patchset, kvm_mmu_pte_write is only a static notifier callback called
by kvm_page_track_write().
And the dirty tracking in emulator_write_phys() is handled in a public API (as my
explanation above), in emulator_cmpxchg_emulated is handled by itself. So i think
it is better to leaving dirty tracking to the separate paths, no? :)
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