linux-kernel - Re: [RFC 6/8]KVM: introduce kvm_mmu_zap

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Date:	Tue, 24 Jul 2007 09:47:59 +0800
From:	Shaohua Li <shaohua.li@...el.com>
To:	Avi Kivity <avi@...ranet.com>
Cc:	kvm-devel <kvm-devel@...ts.sourceforge.net>,
	lkml <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC 6/8]KVM: introduce kvm_mmu_zap_pagetbl

On Mon, 2007-07-23 at 19:16 +0800, Avi Kivity wrote:
> Shaohua Li wrote:
> > add a routine to zap all shadow pgtble for a gfn. If kvm supports
> SMP,
> > the API should zap pgtble for all vcpus, but kvm shadow page table
> > really should be per-vm, instead of per-vcpu.
> >
> >  
> 
> kvm shadow page tables _are_ per-vm.  Current kvm.git even makes that
> more explicit where functions that remove stuff (like rmap_remove())
> don't require a vcpu.
Ok, I didn't check the latest kvm.git.
> 
> > Index: linux/drivers/kvm/kvm.h
> > ===================================================================
> > --- linux.orig/drivers/kvm/kvm.h      2007-07-20 14:19:15.000000000
> +0800
> > +++ linux/drivers/kvm/kvm.h   2007-07-20 14:26:10.000000000 +0800
> > @@ -621,6 +621,7 @@ int kvm_mmu_unprotect_page_virt(struct k
> >  void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);
> >  int kvm_mmu_load(struct kvm_vcpu *vcpu);
> >  void kvm_mmu_unload(struct kvm_vcpu *vcpu);
> > +void kvm_mmu_zap_pagetbl(struct kvm_vcpu *vcpu, u64 gfn);
> > 
> >  int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run);
> > 
> > Index: linux/drivers/kvm/mmu.c
> > ===================================================================
> > --- linux.orig/drivers/kvm/mmu.c      2007-07-20 14:25:25.000000000
> +0800
> > +++ linux/drivers/kvm/mmu.c   2007-07-20 14:26:10.000000000 +0800
> > @@ -1324,6 +1324,34 @@ void kvm_mmu_zap_all(struct kvm_vcpu *vc
> >       init_kvm_mmu(vcpu);
> >  }
> > 
> > +/* FIXME: this should zap all vcpu's shadow pgtbl for gfn */
> > +void kvm_mmu_zap_pagetbl(struct kvm_vcpu *vcpu, u64 gfn)
> > +{
> > +     struct kvm *kvm = vcpu->kvm;
> > +     struct kvm_rmap_desc *desc;
> > +     struct page *page;
> > +     u64 *spte;
> > +
> > +     page = gfn_to_page(kvm, gfn);
> > +     BUG_ON(!page);
> > +
> > +     while (page_private(page)) {
> > +             if (!(page_private(page) & 1))
> > +                     spte = (u64 *)page_private(page);
> > +             else {
> > +                     desc = (struct kvm_rmap_desc
> *)(page_private(page) & ~1ul);
> > +                     spte = desc->shadow_ptes[0];
> > +             }
> > +             BUG_ON(!spte);
> > +             BUG_ON((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT
> > +                     != page_to_pfn(page));
> > +             BUG_ON(!(*spte & PT_PRESENT_MASK));
> > +             rmap_remove(vcpu, spte);
> > +             *spte = 0;
> > +     }
> > +     kvm_flush_remote_tlbs(vcpu->kvm);
> > +}
> > +
> 
> Suggest kvm_mmu_unmap_page() as a name for this.
ok.

Thanks,
Shaohua
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