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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>
hifive-unleashed-5.1
Takuya Yoshikawa 2014-02-18 17:22:47 +09:00 committed by Paolo Bonzini
parent f18eb31f9d
commit 5befdc385d
3 changed files with 8 additions and 8 deletions
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7
arch/x86/kvm/paging_tmpl.h
View File

@ -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;
}

4
include/linux/kvm_host.h
View File

@ -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;
};

5
virt/kvm/kvm_main.c
View File

@ -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);