Messages in this thread Patch in this message | | | Date | Tue, 15 Jun 2010 10:46:39 +0800 | From | Xiao Guangrong <> | Subject | [PATCH 2/6] 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
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> --- arch/x86/kvm/paging_tmpl.h | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 3ebc5a0..eb47148 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -339,6 +339,8 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, direct = 1; if (!is_dirty_gpte(gw->ptes[level - delta])) 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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