On Sunday 31 August 2008 23:13:54 Avi Kivity wrote:
> [EMAIL PROTECTED] wrote:
> > From: Sheng Yang <[EMAIL PROTECTED]>
> >
> > We use a "fake" A/D bit for EPT, to keep epte behaviour consistent with
> > shadow spte. But it's not that good for MMU notifier. Now we can only
> > expect return young=0 for clean_flush_young() in most condition.
>
> Perhaps we are better off setting shadow_accessed_mask to 0 for ept, and
> adding a test for clear_flush_young()? This is the only place that
> needs adjusting as far as I can tell.
>
> I don't see what having a fake accessed bit buys us, and I'd like the
> patch to be as small as possible, since it needs to go into
> 2.6.26-stable and 2.6.27-rc.
Though I still think fake accessed bit here makes logic consistent, here is
the patch follow your comment. But I think it may not necessary for the
2.6.26-stable?
----
From: Sheng Yang <[EMAIL PROTECTED]>
Date: Mon, 1 Sep 2008 13:22:09 +0800
Subject: [PATCH] KVM: VMX: Always return 0 for clear_flush_young() when using
EPT
As well as discard fake accessed bit and dirty bit of EPT.
Signed-off-by: Sheng Yang <[EMAIL PROTECTED]>
---
arch/x86/kvm/mmu.c | 15 +++++++++++----
arch/x86/kvm/vmx.c | 3 +--
arch/x86/kvm/vmx.h | 2 --
3 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f33c594..e437985 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -716,10 +716,17 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long
*rmapp)
int _young;
u64 _spte = *spte;
BUG_ON(!(_spte & PT_PRESENT_MASK));
- _young = _spte & PT_ACCESSED_MASK;
- if (_young) {
- young = 1;
- clear_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte);
+
+ /* always return old for EPT */
+ if (!shadow_accessed_mask)
+ _young = 0;
+ else {
+ _young = _spte & PT_ACCESSED_MASK;
+ if (_young) {
+ young = 1;
+ clear_bit(PT_ACCESSED_SHIFT,
+ (unsigned long *)spte);
+ }
}
spte = rmap_next(kvm, rmapp, spte);
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 81c121c..d637897 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3557,8 +3557,7 @@ static int __init vmx_init(void)
kvm_mmu_set_base_ptes(VMX_EPT_READABLE_MASK |
VMX_EPT_WRITABLE_MASK |
VMX_EPT_DEFAULT_MT << VMX_EPT_MT_EPTE_SHIFT);
- kvm_mmu_set_mask_ptes(0ull, VMX_EPT_FAKE_ACCESSED_MASK,
- VMX_EPT_FAKE_DIRTY_MASK, 0ull,
+ kvm_mmu_set_mask_ptes(0ull, 0ull, 0ull, 0ull,
VMX_EPT_EXECUTABLE_MASK);
kvm_enable_tdp();
} else
diff --git a/arch/x86/kvm/vmx.h b/arch/x86/kvm/vmx.h
index 0c22e5f..41e8c10 100644
--- a/arch/x86/kvm/vmx.h
+++ b/arch/x86/kvm/vmx.h
@@ -370,8 +370,6 @@ enum vmcs_field {
#define VMX_EPT_READABLE_MASK 0x1ull
#define VMX_EPT_WRITABLE_MASK 0x2ull
#define VMX_EPT_EXECUTABLE_MASK 0x4ull
-#define VMX_EPT_FAKE_ACCESSED_MASK (1ull << 62)
-#define VMX_EPT_FAKE_DIRTY_MASK (1ull << 63)
#define VMX_EPT_IDENTITY_PAGETABLE_ADDR 0xfffbc000ul
--
1.5.4.5
From 23229946e717294091bf54cee704fb3b1cd4167d Mon Sep 17 00:00:00 2001
From: Sheng Yang <[EMAIL PROTECTED]>
Date: Mon, 1 Sep 2008 13:22:09 +0800
Subject: [PATCH] KVM: VMX: Always return 0 for clear_flush_young() when using EPT
As well as discard fake accessed bit and dirty bit of EPT.
Signed-off-by: Sheng Yang <[EMAIL PROTECTED]>
---
arch/x86/kvm/mmu.c | 15 +++++++++++----
arch/x86/kvm/vmx.c | 3 +--
arch/x86/kvm/vmx.h | 2 --
3 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f33c594..e437985 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -716,10 +716,17 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp)
int _young;
u64 _spte = *spte;
BUG_ON(!(_spte & PT_PRESENT_MASK));
- _young = _spte & PT_ACCESSED_MASK;
- if (_young) {
- young = 1;
- clear_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte);
+
+ /* always return old for EPT */
+ if (!shadow_accessed_mask)
+ _young = 0;
+ else {
+ _young = _spte & PT_ACCESSED_MASK;
+ if (_young) {
+ young = 1;
+ clear_bit(PT_ACCESSED_SHIFT,
+ (unsigned long *)spte);
+ }
}
spte = rmap_next(kvm, rmapp, spte);
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 81c121c..d637897 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3557,8 +3557,7 @@ static int __init vmx_init(void)
kvm_mmu_set_base_ptes(VMX_EPT_READABLE_MASK |
VMX_EPT_WRITABLE_MASK |
VMX_EPT_DEFAULT_MT << VMX_EPT_MT_EPTE_SHIFT);
- kvm_mmu_set_mask_ptes(0ull, VMX_EPT_FAKE_ACCESSED_MASK,
- VMX_EPT_FAKE_DIRTY_MASK, 0ull,
+ kvm_mmu_set_mask_ptes(0ull, 0ull, 0ull, 0ull,
VMX_EPT_EXECUTABLE_MASK);
kvm_enable_tdp();
} else
diff --git a/arch/x86/kvm/vmx.h b/arch/x86/kvm/vmx.h
index 0c22e5f..41e8c10 100644
--- a/arch/x86/kvm/vmx.h
+++ b/arch/x86/kvm/vmx.h
@@ -370,8 +370,6 @@ enum vmcs_field {
#define VMX_EPT_READABLE_MASK 0x1ull
#define VMX_EPT_WRITABLE_MASK 0x2ull
#define VMX_EPT_EXECUTABLE_MASK 0x4ull
-#define VMX_EPT_FAKE_ACCESSED_MASK (1ull << 62)
-#define VMX_EPT_FAKE_DIRTY_MASK (1ull << 63)
#define VMX_EPT_IDENTITY_PAGETABLE_ADDR 0xfffbc000ul
--
1.5.4.5
