linux-kernel - [PATCH 2/8] KVM: MMU: set the dirty bit for the upper shadow page

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Message-ID: <4EEB1A00.8090707@linux.vnet.ibm.com>
Date:	Fri, 16 Dec 2011 18:14:24 +0800
From:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
CC:	Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: [PATCH 2/8] KVM: MMU: set the dirty bit for the upper shadow page

Upper page do not need to be tracked the status bit, it is safe to set the
dirty and let cpu to happily prefetch it

Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
---
 arch/x86/kvm/mmu.c |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 6913a16..a2d28aa 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -150,6 +150,9 @@ module_param(dbg, bool, 0644);
 #define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)

 #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
+#define SHADOW_PAGE_TABLE						\
+	(PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask |	\
+	 shadow_x_mask | shadow_accessed_mask | shadow_dirty_mask)

 static bool sp_is_unsync(struct kvm_mmu_page *sp)
 {
@@ -1808,9 +1811,7 @@ static void link_shadow_page(u64 *sptep, struct kvm_mmu_page *sp)
 {
 	u64 spte;

-	spte = __pa(sp->spt)
-		| PT_PRESENT_MASK | PT_ACCESSED_MASK
-		| PT_WRITABLE_MASK | PT_USER_MASK;
+	spte = __pa(sp->spt) | SHADOW_PAGE_TABLE;
 	mmu_spte_set(sptep, spte);
 }

@@ -2497,11 +2498,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
 				return -ENOMEM;
 			}

-			mmu_spte_set(iterator.sptep,
-				     __pa(sp->spt)
-				     | PT_PRESENT_MASK | PT_WRITABLE_MASK
-				     | shadow_user_mask | shadow_x_mask
-				     | shadow_accessed_mask);
+			link_shadow_page(iterator.sptep, sp);
 		}
 	}
 	return emulate;
-- 
1.7.7.4

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