linux-kernel - [PATCH v3 4/4] Enabling Access bit when doing memory swapping

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Date:	Tue, 22 May 2012 11:23:15 +0800
From:	Xudong Hao <xudong.hao@...el.com>
To:	avi@...hat.com
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	mtosatti@...hat.com, takuya.yoshikawa@...il.com,
	xiantao.zhang@...el.com, Xudong Hao <xudong.hao@...el.com>,
	Haitao Shan <haitao.shan@...el.com>
Subject: [PATCH v3 4/4] Enabling Access bit when doing memory swapping

<Re-send>

Enabling Access bit when doing memory swapping.

Changes from v2:
-Still using claer_bit() function to make sure it's atomic operation.

Signed-off-by: Haitao Shan <haitao.shan@...el.com>
Signed-off-by: Xudong Hao <xudong.hao@...el.com>
---
 arch/x86/kvm/mmu.c |   14 ++++++++------
 arch/x86/kvm/vmx.c |    6 ++++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 72102e0..c2fef8e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1242,7 +1242,8 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
 	int young = 0;
 
 	/*
-	 * Emulate the accessed bit for EPT, by checking if this page has
+	 * In case of absence of EPT Access and Dirty Bits supports,
+	 * emulate the accessed bit for EPT, by checking if this page has
 	 * an EPT mapping, and clearing it if it does. On the next access,
 	 * a new EPT mapping will be established.
 	 * This has some overhead, but not as much as the cost of swapping
@@ -1253,11 +1254,12 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
 
 	for (sptep = rmap_get_first(*rmapp, &iter); sptep;
 	     sptep = rmap_get_next(&iter)) {
-		BUG_ON(!(*sptep & PT_PRESENT_MASK));
+		BUG_ON(!is_shadow_present_pte(*sptep));
 
-		if (*sptep & PT_ACCESSED_MASK) {
+		if (*sptep & shadow_accessed_mask) {
 			young = 1;
-			clear_bit(PT_ACCESSED_SHIFT, (unsigned long *)sptep);
+			clear_bit((ffs(shadow_accessed_mask) - 1),
+				 (unsigned long *)sptep);
 		}
 	}
 
@@ -1281,9 +1283,9 @@ static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
 
 	for (sptep = rmap_get_first(*rmapp, &iter); sptep;
 	     sptep = rmap_get_next(&iter)) {
-		BUG_ON(!(*sptep & PT_PRESENT_MASK));
+		BUG_ON(!is_shadow_present_pte(*sptep));
 
-		if (*sptep & PT_ACCESSED_MASK) {
+		if (*sptep & shadow_accessed_mask) {
 			young = 1;
 			break;
 		}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 32eb588..ea6390e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7275,8 +7275,10 @@ static int __init vmx_init(void)
 	vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_EIP, false);
 
 	if (enable_ept) {
-		kvm_mmu_set_mask_ptes(0ull, 0ull, 0ull, 0ull,
-				VMX_EPT_EXECUTABLE_MASK);
+		kvm_mmu_set_mask_ptes(0ull,
+			(enable_ept_ad_bits) ? VMX_EPT_ACCESS_BIT : 0ull,
+			(enable_ept_ad_bits) ? VMX_EPT_DIRTY_BIT : 0ull,
+			0ull, VMX_EPT_EXECUTABLE_MASK);
 		ept_set_mmio_spte_mask();
 		kvm_enable_tdp();
 	} else
-- 
1.5.6

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