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SubjectRe: [PATCH 14/27] KVM: MMU: Make walk_addr_generic capable for two-level walking
On Mon, Sep 06, 2010 at 05:55:53PM +0200, Joerg Roedel wrote:
> This patch uses kvm_read_guest_page_tdp to make the
> walk_addr_generic functions suitable for two-level page
> table walking.
>
> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
> ---
> arch/x86/kvm/paging_tmpl.h | 27 ++++++++++++++++++++-------
> 1 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> index cd59af1..a5b5759 100644
> --- a/arch/x86/kvm/paging_tmpl.h
> +++ b/arch/x86/kvm/paging_tmpl.h
> @@ -124,6 +124,8 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
> unsigned index, pt_access, uninitialized_var(pte_access);
> gpa_t pte_gpa;
> bool eperm, present, rsvd_fault;
> + int offset;
> + u32 error = 0;
>
> trace_kvm_mmu_pagetable_walk(addr, write_fault, user_fault,
> fetch_fault);
> @@ -153,12 +155,13 @@ walk:
> index = PT_INDEX(addr, walker->level);
>
> table_gfn = gpte_to_gfn(pte);
> - pte_gpa = gfn_to_gpa(table_gfn);
> - pte_gpa += index * sizeof(pt_element_t);
> + offset = index * sizeof(pt_element_t);
> + pte_gpa = gfn_to_gpa(table_gfn) + offset;
> walker->table_gfn[walker->level - 1] = table_gfn;
> walker->pte_gpa[walker->level - 1] = pte_gpa;
>
> - if (kvm_read_guest(vcpu->kvm, pte_gpa, &pte, sizeof(pte))) {
> + if (kvm_read_guest_page_mmu(vcpu, mmu, table_gfn, &pte, offset,
> + sizeof(pte), &error)) {
> present = false;
> break;
> }

If there is failure reading the nested page tables here, you fill
vcpu->arch.fault. But the nested fault error values will be overwritten
at the end of walk_addr() by the original fault values?

> @@ -209,15 +212,25 @@ walk:
> is_large_pte(pte) &&
> mmu->root_level == PT64_ROOT_LEVEL)) {
> int lvl = walker->level;
> + gpa_t real_gpa;
> + gfn_t gfn;
>
> - walker->gfn = gpte_to_gfn_lvl(pte, lvl);
> - walker->gfn += (addr & PT_LVL_OFFSET_MASK(lvl))
> - >> PAGE_SHIFT;
> + gfn = gpte_to_gfn_lvl(pte, lvl);
> + gfn += (addr & PT_LVL_OFFSET_MASK(lvl)) >> PAGE_SHIFT;
>
> if (PTTYPE == 32 &&
> walker->level == PT_DIRECTORY_LEVEL &&
> is_cpuid_PSE36())
> - walker->gfn += pse36_gfn_delta(pte);
> + gfn += pse36_gfn_delta(pte);
> +
> + real_gpa = mmu->translate_gpa(vcpu, gfn_to_gpa(gfn),
> + &error);
> + if (real_gpa == UNMAPPED_GVA) {
> + walker->error_code = error;
> + return 0;
> + }
> +
> + walker->gfn = real_gpa >> PAGE_SHIFT;
>
> break;
> }
> --
> 1.7.0.4
>


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