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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 16 May 2012 09:12:30 +0800
From:	Xudong Hao <xudong.hao@...ux.intel.com>
To:	avi@...hat.com
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	haitao.shan@...el.com, xiantao.zhang@...el.com,
	xudong.hao@...el.com
Subject: [PATCH 4/4] Enabling Access bit when doing memory swapping

Enabling Access bit when doing memory swapping.

Signed-off-by: Haitao Shan <haitao.shan@...el.com>
Signed-off-by: Xudong Hao <xudong.hao@...el.com>
---
 arch/x86/kvm/mmu.c |   13 +++++++------
 arch/x86/kvm/vmx.c |    6 ++++--
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ff053ca..5f55f98 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1166,7 +1166,8 @@ 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
@@ -1179,11 +1180,11 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
    while (spte) {
        int _young;
        u64 _spte = *spte;
-       BUG_ON(!(_spte & PT_PRESENT_MASK));
-       _young = _spte & PT_ACCESSED_MASK;
+       BUG_ON(!is_shadow_present_pte(_spte));
+       _young = _spte & shadow_accessed_mask;
        if (_young) {
            young = 1;
-           clear_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte);
+           *spte &= ~shadow_accessed_mask;
        }
        spte = rmap_next(rmapp, spte);
    }
@@ -1207,8 +1208,8 @@ static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
    spte = rmap_next(rmapp, NULL);
    while (spte) {
        u64 _spte = *spte;
-       BUG_ON(!(_spte & PT_PRESENT_MASK));
-       young = _spte & PT_ACCESSED_MASK;
+       BUG_ON(!is_shadow_present_pte(_spte));
+       young = _spte & shadow_accessed_mask;
        if (young) {
            young = 1;
            break;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 89151a9..a3ef549 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7242,8 +7242,10 @@ 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
--
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/