Current permission check assumes that RSVD bit in PFEC is always zero,
however, it is not true since MMIO #PF will use it to quickly identify
MMIO access
Fix it by clearing the bit if walking guest page table is needed
Signed-off-by: Xiao Guangrong <guangrong.x...@linux.intel.com>
---
arch/x86/kvm/mmu.h | 2 ++
arch/x86/kvm/paging_tmpl.h | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index c7d6563..06eb2fc 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -166,6 +166,8 @@ static inline bool permission_fault(struct kvm_vcpu *vcpu,
struct kvm_mmu *mmu,
int index = (pfec >> 1) +
(smap >> (X86_EFLAGS_AC_BIT - PFERR_RSVD_BIT + 1));
+ WARN_ON(pfec & PFERR_RSVD_MASK);
+
return (mmu->permissions[index] >> pte_access) & 1;
}
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index fd49c86..6e6d115 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -718,6 +718,13 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t
addr, u32 error_code,
mmu_is_nested(vcpu));
if (likely(r != RET_MMIO_PF_INVALID))
return r;
+
+ /*
+ * page fault with PFEC.RSVD = 1 is caused by shadow
+ * page fault, should not be used to walk guest page
+ * table.
+ */
+ error_code &= ~PFERR_RSVD_MASK;
};
r = mmu_topup_memory_caches(vcpu);
--
2.1.0
--
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