Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 26 Apr 2010 10:39:24 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH v2 1/10] KVM MMU: fix for calculating gpa in invlpg code |
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On 04/26/2010 06:10 AM, Xiao Guangrong wrote: > > Avi Kivity wrote: > >> On 04/25/2010 10:00 AM, Xiao Guangrong wrote: >> >>> If the guest is 32-bit, we should use 'quadrant' to adjust gpa >>> offset >>> >>> Changlog v2: >>> - when level is PT_DIRECTORY_LEVEL, the 'offset' should be >>> 'role.quadrant<< 8', thanks Avi for point it out >>> >>> Signed-off-by: Xiao Guangrong<xiaoguangrong@cn.fujitsu.com> >>> --- >>> arch/x86/kvm/paging_tmpl.h | 13 +++++++++++-- >>> 1 files changed, 11 insertions(+), 2 deletions(-) >>> >>> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h >>> index d0cc07e..83cc72f 100644 >>> --- a/arch/x86/kvm/paging_tmpl.h >>> +++ b/arch/x86/kvm/paging_tmpl.h >>> @@ -478,9 +478,18 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, >>> gva_t gva) >>> ((level == PT_DIRECTORY_LEVEL&& is_large_pte(*sptep))) || >>> ((level == PT_PDPE_LEVEL&& is_large_pte(*sptep)))) { >>> struct kvm_mmu_page *sp = page_header(__pa(sptep)); >>> - >>> + int offset = 0; >>> + >>> + if (PTTYPE == 32) { >>> + if (level == PT_DIRECTORY_LEVEL) >>> + offset = PAGE_SHIFT - 4; >>> + else >>> + offset = PT64_LEVEL_BITS; >>> + offset = sp->role.quadrant<< offset; >>> + } >>> >>> >> The calculation is really >> >> shift = (PT32_LEVEL_BITS - PT64_LEVEL_BITS) * level; >> >> > So, the offset is q<< (PAGE_SHIFT - (PT32_LEVEL_BITS - PT64_LEVEL_BITS) * level - 2)? >
Ugh, what I meant was
shift = PAGE_SHIFT - (PT_LEVEL_BITS - PT64_LEVEL_BITS) * level; offset = q << shift
so,
pte_gpa = (sp->gfn << PAGE_SHIFT) + offset + (spte - sp->spt) * sizeof(pt_element_t)
No magic numbers please. Note it could work without the 'if (PTTYPE == 32)'.
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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