linux-kernel - [PATCH 1/2] kvm: mmu: fix catch transparent huge page backing

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Date:	Tue, 14 Apr 2015 13:51:29 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Andres Lagar-Cavilla <andreslc@...gle.com>,
	Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
	Eric Northup <digitaleric@...gle.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Wanpeng Li <wanpeng.li@...ux.intel.com>
Subject: [PATCH 1/2] kvm: mmu: fix catch transparent huge page backing

PageTransCompound() can't guarantee the page is a transparent huge page
since it returns true for both transparent huge and hugetlbfs pages.

This patch fixes it by checking the page is also !hugetlbfs page.

Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
---
 arch/x86/kvm/mmu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 146f295..2a0d77e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4487,7 +4487,8 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 		 */
 		if (sp->role.direct &&
 			!kvm_is_reserved_pfn(pfn) &&
-			PageTransCompound(pfn_to_page(pfn))) {
+			!PageHuge(pfn_to_page(pfn)) &&
+			PageTransHuge(pfn_to_page(pfn))) {
 			drop_spte(kvm, sptep);
 			sptep = rmap_get_first(*rmapp, &iter);
 			need_tlb_flush = 1;
-- 
1.9.1

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