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

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Message-ID: <403610A45A2B5242BD291EDAE8B37D300FDCA338@SHSMSX102.ccr.corp.intel.com>
Date:	Mon, 28 May 2012 10:21:03 +0000
From:	"Hao, Xudong" <xudong.hao@...el.com>
To:	"'avi@...hat.com'" <avi@...hat.com>
CC:	"'kvm@...r.kernel.org'" <kvm@...r.kernel.org>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'mtosatti@...hat.com'" <mtosatti@...hat.com>,
	"'takuya.yoshikawa@...il.com'" <takuya.yoshikawa@...il.com>,
	"Zhang, Xiantao" <xiantao.zhang@...el.com>,
	"Shan, Haitao" <haitao.shan@...el.com>
Subject: RE: [PATCH v3 4/4] Enabling Access bit when doing memory swapping

> -----Original Message-----
> From: Hao, Xudong
> Sent: Wednesday, May 23, 2012 9:31 PM
> To: avi@...hat.com
> Cc: kvm@...r.kernel.org; linux-kernel@...r.kernel.org; mtosatti@...hat.com;
> takuya.yoshikawa@...il.com; Zhang, Xiantao; Shan, Haitao
> Subject: RE: [PATCH v3 4/4] Enabling Access bit when doing memory swapping
> 
> Hi, Avi
> 
> Will these patches be accepted if no other comments?
> 
> Thanks,
> -Xudong
> 
> 
> > -----Original Message-----
> > From: Hao, Xudong
> > Sent: Tuesday, May 22, 2012 11:23 AM
> > To: avi@...hat.com
> > Cc: kvm@...r.kernel.org; linux-kernel@...r.kernel.org;
> mtosatti@...hat.com;
> > takuya.yoshikawa@...il.com; Zhang, Xiantao; Hao, Xudong; Shan, Haitao
> > 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

Hi, Avi

Do you have other comments for this series of patches?
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