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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/7] KVM: x86/mmu: Fix struct guest_walker arrays for 5-level paging
Date: Fri,  7 Feb 2020 09:37:42 -0800	[thread overview]
Message-ID: <20200207173747.6243-3-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200207173747.6243-1-sean.j.christopherson@intel.com>

Define PT_MAX_FULL_LEVELS as PT64_ROOT_MAX_LEVEL, i.e. 5, to fix shadow
paging for 5-level guest page tables.  PT_MAX_FULL_LEVELS is used to
size the arrays that track guest pages table information, i.e. using a
"max levels" of 4 causes KVM to access garbage beyond the end of an
array when querying state for level 5 entries.  E.g. FNAME(gpte_changed)
will read garbage and most likely return %true for a level 5 entry,
soft-hanging the guest because FNAME(fetch) will restart the guest
instead of creating SPTEs because it thinks the guest PTE has changed.

Note, KVM doesn't yet support 5-level nested EPT, so PT_MAX_FULL_LEVELS
gets to stay "4" for the PTTYPE_EPT case.

Fixes: 855feb673640 ("KVM: MMU: Add 5 level EPT & Shadow page table support.")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/mmu/paging_tmpl.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 4e1ef0473663..e4c8a4cbf407 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -33,7 +33,7 @@
 	#define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT
 	#define PT_HAVE_ACCESSED_DIRTY(mmu) true
 	#ifdef CONFIG_X86_64
-	#define PT_MAX_FULL_LEVELS 4
+	#define PT_MAX_FULL_LEVELS PT64_ROOT_MAX_LEVEL
 	#define CMPXCHG cmpxchg
 	#else
 	#define CMPXCHG cmpxchg64
-- 
2.24.1


  parent reply	other threads:[~2020-02-07 17:38 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07 17:37 [PATCH v2 0/7] KVM: x86/mmu: nVMX: 5-level paging fixes and enabling Sean Christopherson
2020-02-07 17:37 ` [PATCH v2 1/7] KVM: nVMX: Use correct root level for nested EPT shadow page tables Sean Christopherson
2020-02-07 17:37 ` Sean Christopherson [this message]
2020-02-07 17:37 ` [PATCH v2 3/7] KVM: nVMX: Allow L1 to use 5-level page walks for nested EPT Sean Christopherson
2020-02-07 17:37 ` [PATCH v2 4/7] KVM: nVMX: Rename nested_ept_get_cr3() to nested_ept_get_eptp() Sean Christopherson
2020-02-07 17:37 ` [PATCH v2 5/7] KVM: nVMX: Rename EPTP validity helper and associated variables Sean Christopherson
2020-02-07 17:37 ` [PATCH v2 6/7] KVM: x86/mmu: Rename kvm_mmu->get_cr3() to ->get_guest_cr3_or_eptp() Sean Christopherson
2020-02-12 12:00   ` Paolo Bonzini
2020-02-12 16:28     ` Sean Christopherson
2020-02-12 16:42       ` Paolo Bonzini
2020-03-01 17:49         ` Sean Christopherson
2020-02-07 17:37 ` [PATCH v2 7/7] KVM: nVMX: Drop unnecessary check on ept caps for execute-only Sean Christopherson
2020-02-12 12:03 ` [PATCH v2 0/7] KVM: x86/mmu: nVMX: 5-level paging fixes and enabling Paolo Bonzini

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