From 3d000db5688c8beff6319fb9ff4b98dcac32f798 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Fri, 22 Aug 2008 19:24:38 +0300 Subject: [PATCH] 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 --- arch/x86/kvm/mmu.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 72f739aa862..8b95cf748b5 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -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) { -- 2.41.1