Messages in this thread | | | Date | Sun, 19 May 2013 13:47:13 +0300 | From | Gleb Natapov <> | Subject | Re: [PATCH v6 2/7] KVM: MMU: delete shadow page from hash list in kvm_mmu_prepare_zap_page |
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On Fri, May 17, 2013 at 05:12:57AM +0800, Xiao Guangrong wrote: > Move deletion shadow page from the hash list from kvm_mmu_commit_zap_page to > kvm_mmu_prepare_zap_page so that we can call kvm_mmu_commit_zap_page > once for multiple kvm_mmu_prepare_zap_page that can help us to avoid > unnecessary TLB flush > Don't we call kvm_mmu_commit_zap_page() once for multiple kvm_mmu_prepare_zap_page() now when possible? kvm_mmu_commit_zap_page() gets a list as a parameter. I am not against the change, but wish to understand it better.
> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> > --- > arch/x86/kvm/mmu.c | 8 ++++++-- > 1 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 40d7b2d..682ecb4 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -1466,7 +1466,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr) > static void kvm_mmu_free_page(struct kvm_mmu_page *sp) > { > ASSERT(is_empty_shadow_page(sp->spt)); > - hlist_del(&sp->hash_link); > + > list_del(&sp->link); > free_page((unsigned long)sp->spt); > if (!sp->role.direct) > @@ -1655,7 +1655,8 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, > > #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ > for_each_gfn_sp(_kvm, _sp, _gfn) \ > - if ((_sp)->role.direct || (_sp)->role.invalid) {} else > + if ((_sp)->role.direct || \ > + ((_sp)->role.invalid && WARN_ON(1))) {} else > > /* @sp->gfn should be write-protected at the call site */ > static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > @@ -2074,6 +2075,9 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, > unaccount_shadowed(kvm, sp->gfn); > if (sp->unsync) > kvm_unlink_unsync_page(kvm, sp); > + > + hlist_del_init(&sp->hash_link); > + What about moving this inside if() bellow and making it hlist_del()? Leave the page on the hash if root_count is non zero.
> if (!sp->root_count) { > /* Count self */ > ret++; > -- > 1.7.7.6
-- Gleb.
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