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authorTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>2014-02-18 17:22:47 +0900
committerPaolo Bonzini <pbonzini@redhat.com>2014-02-18 10:07:26 +0100
commit5befdc385ddb2d5ae8995ad89004529a3acf58fc (patch)
treee31e48e6f1f810596b6c5ca9663c02c02ed319b5
parentf18eb31f9df52c28ec86d18d72f66ef689878daa (diff)
KVM: Simplify kvm->tlbs_dirty handling
When this was introduced, kvm_flush_remote_tlbs() could be called without holding mmu_lock. It is now acknowledged that the function must be called before releasing mmu_lock, and all callers have already been changed to do so. There is no need to use smp_mb() and cmpxchg() any more. Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/kvm/paging_tmpl.h7
-rw-r--r--include/linux/kvm_host.h4
-rw-r--r--virt/kvm/kvm_main.c5
3 files changed, 8 insertions, 8 deletions
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index cba218a2f08d..b1e6c1bf68d3 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -913,7 +913,8 @@ static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gva_t vaddr,
* and kvm_mmu_notifier_invalidate_range_start detect the mapping page isn't
* used by guest then tlbs are not flushed, so guest is allowed to access the
* freed pages.
- * And we increase kvm->tlbs_dirty to delay tlbs flush in this case.
+ * We set tlbs_dirty to let the notifier know this change and delay the flush
+ * until such a case actually happens.
*/
static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
@@ -942,7 +943,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
return -EINVAL;
if (FNAME(prefetch_invalid_gpte)(vcpu, sp, &sp->spt[i], gpte)) {
- vcpu->kvm->tlbs_dirty++;
+ vcpu->kvm->tlbs_dirty = true;
continue;
}
@@ -957,7 +958,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
if (gfn != sp->gfns[i]) {
drop_spte(vcpu->kvm, &sp->spt[i]);
- vcpu->kvm->tlbs_dirty++;
+ vcpu->kvm->tlbs_dirty = true;
continue;
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f5937b8188b4..9816b68b085f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -401,7 +401,9 @@ struct kvm {
unsigned long mmu_notifier_seq;
long mmu_notifier_count;
#endif
- long tlbs_dirty;
+ /* Protected by mmu_lock */
+ bool tlbs_dirty;
+
struct list_head devices;
};
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a9e999a48e43..f5668a431d54 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -186,12 +186,9 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
void kvm_flush_remote_tlbs(struct kvm *kvm)
{
- long dirty_count = kvm->tlbs_dirty;
-
- smp_mb();
if (make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
++kvm->stat.remote_tlb_flush;
- cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);
+ kvm->tlbs_dirty = false;
}
EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);