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Commit 3d000db5 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: MMU: Add generic shadow walker 



We currently walk the shadow page tables in two places: direct map (for
real mode and two dimensional paging) and paging mode shadow.  Since we
anticipate requiring a third walk (for invlpg), it makes sense to have
a generic facility for shadow walk.

This patch adds such a shadow walker, walks the page tables and calls a
method for every spte encountered.  The method can examine the spte,
modify it, or even instantiate it.  The walk can be aborted by returning
nonzero from the method.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 6c41f428

arch/x86/kvm/mmu.c

+34 −0
Original line number Diff line number Diff line
@@ -142,6 +142,11 @@ struct kvm_rmap_desc { 
	struct kvm_rmap_desc *more;

};



struct kvm_shadow_walk {

	int (*entry)(struct kvm_shadow_walk *walk, struct kvm_vcpu *vcpu,

		     gva_t addr, u64 *spte, int level);

};



static struct kmem_cache *pte_chain_cache;

static struct kmem_cache *rmap_desc_cache;

static struct kmem_cache *mmu_page_header_cache;
@@ -935,6 +940,35 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 
	return sp;

}



static int walk_shadow(struct kvm_shadow_walk *walker,

		       struct kvm_vcpu *vcpu, gva_t addr)

{

	hpa_t shadow_addr;

	int level;

	int r;

	u64 *sptep;

	unsigned index;



	shadow_addr = vcpu->arch.mmu.root_hpa;

	level = vcpu->arch.mmu.shadow_root_level;

	if (level == PT32E_ROOT_LEVEL) {

		shadow_addr = vcpu->arch.mmu.pae_root[(addr >> 30) & 3];

		shadow_addr &= PT64_BASE_ADDR_MASK;

		--level;

	}



	while (level >= PT_PAGE_TABLE_LEVEL) {

		index = SHADOW_PT_INDEX(addr, level);

		sptep = ((u64 *)__va(shadow_addr)) + index;

		r = walker->entry(walker, vcpu, addr, sptep, level);

		if (r)

			return r;

		shadow_addr = *sptep & PT64_BASE_ADDR_MASK;

		--level;

	}

	return 0;

}



static void kvm_mmu_page_unlink_children(struct kvm *kvm,

					 struct kvm_mmu_page *sp)

{