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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: Avi Kivity <avi@qumranet.com>
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@ -142,6 +142,11 @@ struct kvm_rmap_desc {
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struct kvm_rmap_desc *more;
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};
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struct kvm_shadow_walk {
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int (*entry)(struct kvm_shadow_walk *walk, struct kvm_vcpu *vcpu,
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gva_t addr, u64 *spte, int level);
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};
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static struct kmem_cache *pte_chain_cache;
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static struct kmem_cache *rmap_desc_cache;
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static struct kmem_cache *mmu_page_header_cache;
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@ -935,6 +940,35 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
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return sp;
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}
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static int walk_shadow(struct kvm_shadow_walk *walker,
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struct kvm_vcpu *vcpu, gva_t addr)
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{
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hpa_t shadow_addr;
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int level;
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int r;
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u64 *sptep;
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unsigned index;
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shadow_addr = vcpu->arch.mmu.root_hpa;
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level = vcpu->arch.mmu.shadow_root_level;
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if (level == PT32E_ROOT_LEVEL) {
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shadow_addr = vcpu->arch.mmu.pae_root[(addr >> 30) & 3];
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shadow_addr &= PT64_BASE_ADDR_MASK;
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--level;
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}
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while (level >= PT_PAGE_TABLE_LEVEL) {
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index = SHADOW_PT_INDEX(addr, level);
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sptep = ((u64 *)__va(shadow_addr)) + index;
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r = walker->entry(walker, vcpu, addr, sptep, level);
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if (r)
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return r;
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shadow_addr = *sptep & PT64_BASE_ADDR_MASK;
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--level;
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}
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return 0;
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}
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static void kvm_mmu_page_unlink_children(struct kvm *kvm,
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struct kvm_mmu_page *sp)
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{
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