On Tue, Sep 07, 2010 at 01:48:05PM -0400, Marcelo Tosatti wrote:
> 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@xxxxxxx>
> > ---
> > 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?
True. Thanks for pointing that out. I will write a test-case for that
too. The results from my implemented tests show that sometimes the error
code is not reported correctly too. So I decided to do a v4 of this
patch-set with all found issues fixed.
Thanks for your review.
Joerg
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