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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>
This commit is contained in:
Avi Kivity 2008-08-22 19:24:38 +03:00
parent 6c41f428b7
commit 3d000db568
1 changed files with 34 additions and 0 deletions
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34
arch/x86/kvm/mmu.c
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@ -142,6 +142,11 @@ struct kvm_rmap_desc {
struct kvm_rmap_desc *more; 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 *pte_chain_cache;
static struct kmem_cache *rmap_desc_cache; static struct kmem_cache *rmap_desc_cache;
static struct kmem_cache *mmu_page_header_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; 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, static void kvm_mmu_page_unlink_children(struct kvm *kvm,
struct kvm_mmu_page *sp) struct kvm_mmu_page *sp)
{ {