This is a note to let you know that I've just added the patch titled
KVM: MMU: fix smap permission check
to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-mmu-fix-smap-permission-check.patch
and it can be found in the queue-4.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7cbeed9bce7580479bb97457dad220cb3594b875 Mon Sep 17 00:00:00 2001
From: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
Date: Thu, 7 May 2015 16:20:15 +0800
Subject: KVM: MMU: fix smap permission check
From: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
commit 7cbeed9bce7580479bb97457dad220cb3594b875 upstream.
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.xiao@xxxxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.h | 2 ++
arch/x86/kvm/paging_tmpl.h | 7 +++++++
2 files changed, 9 insertions(+)
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -166,6 +166,8 @@ static inline bool permission_fault(stru
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;
}
--- 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_
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);
Patches currently in stable-queue which might be from guangrong.xiao@xxxxxxxxxxxxxxx are
queue-4.0/kvm-mmu-fix-smap-permission-check.patch
queue-4.0/kvm-mmu-fix-cr4.smep-1-cr0.wp-0-with-shadow-pages.patch
queue-4.0/kvm-mmu-fix-smap-virtualization.patch
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