[RFC 6/8]KVM: introduce kvm_mmu_zap_pagetbl

[RFC 6/8]KVM: introduce kvm_mmu_zap_pagetbl

[Shaohua Li]

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.

Signed-off-by: Shaohua Li <shaohua.li-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/kvm/kvm.h |    1 +
 drivers/kvm/mmu.c |   28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

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);
+}
+
 void kvm_mmu_module_exit(void)
 {
 	if (pte_chain_cache)

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Re: [RFC 6/8]KVM: introduce kvm_mmu_zap_pagetbl

[Avi Kivity]

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.


> 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.


-- 
error compiling committee.c: too many arguments to function


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Re: [RFC 6/8]KVM: introduce kvm_mmu_zap_pagetbl

[Shaohua Li]

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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