Messages in this thread Patch in this message | | | Date | Fri, 25 Jun 2010 20:05:39 +0800 | From | Xiao Guangrong <> | Subject | [PATCH v2 2/10] KVM: MMU: fix conflict access permissions in direct sp |
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In no-direct mapping, we mark sp is 'direct' when we mapping the guest's larger page, but its access is encoded form upper page-struct entire not include the last mapping, it will cause access conflict.
For example, have this mapping: [W] / PDE1 -> |---| P[W] | | LPA \ PDE2 -> |---| [R]
P have two children, PDE1 and PDE2, both PDE1 and PDE2 mapping the same lage page(LPA). The P's access is WR, PDE1's access is WR, PDE2's access is RO(just consider read-write permissions here)
When guest access PDE1, we will create a direct sp for LPA, the sp's access is from P, is W, then we will mark the ptes is W in this sp.
Then, guest access PDE2, we will find LPA's shadow page, is the same as PDE's, and mark the ptes is RO.
So, if guest access PDE1, the incorrect #PF is occured.
Fixed by encode the last mapping access into direct shadow page
And, it also cleanup the code that directly get the last level's dirty flag
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> --- arch/x86/kvm/paging_tmpl.h | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 37c26cb..e46eb8a 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -306,6 +306,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, gfn_t table_gfn; int r; int level; + bool dirty = is_dirty_gpte(gw->ptes[gw->level-1]); pt_element_t curr_pte; struct kvm_shadow_walk_iterator iterator; @@ -319,8 +320,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, mmu_set_spte(vcpu, sptep, access, gw->pte_access & access, user_fault, write_fault, - is_dirty_gpte(gw->ptes[gw->level-1]), - ptwrite, level, + dirty, ptwrite, level, gw->gfn, pfn, false, true); break; } @@ -335,10 +335,11 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, } if (level <= gw->level) { - int delta = level - gw->level + 1; direct = 1; - if (!is_dirty_gpte(gw->ptes[level - delta])) + if (!dirty) access &= ~ACC_WRITE_MASK; + access &= gw->pte_access; + /* * It is a large guest pages backed by small host pages, * So we set @direct(@sp->role.direct)=1, and set -- 1.6.1.2
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