From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH v3 05/19] KVM: MMU: optimize to handle dirty bit
Date: Wed, 06 Jul 2011 09:22:28 +0800 [thread overview]
Message-ID: <4E13B8D4.3050704@cn.fujitsu.com> (raw)
In-Reply-To: <20110705192703.GB24417@amt.cnet>
On 07/06/2011 03:27 AM, Marcelo Tosatti wrote:
> On Thu, Jun 30, 2011 at 04:21:30PM +0800, Xiao Guangrong wrote:
>> If dirty bit is not set, we can make the pte access read-only to avoid handing
>> dirty bit everywhere
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
>
>> -static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte)
>> +static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte,
>> + bool last)
>> {
>> unsigned access;
>>
>> access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK;
>> + if (last && !is_dirty_gpte(gpte))
>> + access &= ~ACC_WRITE_MASK;
>> +
>
> What if the walker marks the dirty bit on the gpte?
>
Actually, we get guest pte access after mark the dirty bit:
if (write_fault && unlikely(!is_dirty_gpte(pte))) {
int ret;
trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte));
ret = FNAME(cmpxchg_gpte)(vcpu, mmu, ptep_user, index,
pte, pte|PT_DIRTY_MASK);
if (unlikely(ret < 0)) {
present = false;
goto error;
} else if (ret)
goto walk;
mark_page_dirty(vcpu->kvm, table_gfn);
pte |= PT_DIRTY_MASK;
walker->ptes[walker->level - 1] = pte;
}
pte_access = pt_access & FNAME(gpte_access)(vcpu, pte, true);
So, i think it works well :-)
next prev parent reply other threads:[~2011-07-06 1:20 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-30 8:19 [PATCH v3 01/19] KVM: MMU: fix walking shadow page table Xiao Guangrong
2011-06-30 8:19 ` [PATCH v3 02/19] KVM: MMU: do not update slot bitmap if spte is nonpresent Xiao Guangrong
2011-06-30 8:20 ` [PATCH v3 03/19] KVM: x86: introduce vcpu_mmio_gva_to_gpa to cleanup the code Xiao Guangrong
2011-06-30 8:20 ` [PATCH v3 04/19] KVM: MMU: cache mmio info on page fault path Xiao Guangrong
2011-07-05 19:04 ` Marcelo Tosatti
2011-07-06 1:17 ` Xiao Guangrong
2011-06-30 8:21 ` [PATCH v3 05/19] KVM: MMU: optimize to handle dirty bit Xiao Guangrong
2011-07-05 19:27 ` Marcelo Tosatti
2011-07-06 1:22 ` Xiao Guangrong [this message]
2011-07-06 16:51 ` Marcelo Tosatti
2011-07-06 19:12 ` Xiao Guangrong
2011-07-07 8:15 ` Marcelo Tosatti
2011-06-30 8:21 ` [PATCH v3 06/19] KVM: MMU: cleanup for FNAME(fetch) Xiao Guangrong
2011-06-30 8:22 ` [PATCH v3 07/19] KVM: MMU: rename 'pt_write' to 'emulate' Xiao Guangrong
2011-06-30 8:22 ` [PATCH v3 08/19] KVM: MMU: count used shadow pages on prepareing path Xiao Guangrong
2011-06-30 8:23 ` [PATCH v3 09/19] KVM: MMU: split kvm_mmu_free_page Xiao Guangrong
2011-06-30 8:23 ` [PATCH v3 10/19] KVM: MMU: remove bypass_guest_pf Xiao Guangrong
2011-06-30 8:24 ` [PATCH v3 11/19] KVM: MMU: filter out the mmio pfn from the fault pfn Xiao Guangrong
2011-07-06 17:17 ` Marcelo Tosatti
2011-07-06 19:13 ` Xiao Guangrong
2011-06-30 8:24 ` [PATCH v3 12/19] KVM: MMU: abstract some functions to handle " Xiao Guangrong
2011-06-30 8:25 ` [PATCH v3 13/19] KVM: MMU: introduce the rules to modify shadow page table Xiao Guangrong
2011-06-30 8:25 ` [PATCH v3 14/19] KVM: MMU: clean up spte updating and clearing Xiao Guangrong
2011-07-06 17:39 ` Marcelo Tosatti
2011-07-06 19:18 ` Xiao Guangrong
2011-07-07 8:16 ` Marcelo Tosatti
2011-07-07 9:30 ` Xiao Guangrong
2011-06-30 8:26 ` [PATCH v3 15/19] KVM: MMU: do not need atomicly to set/clear spte Xiao Guangrong
2011-06-30 8:26 ` [PATCH v3 16/19] KVM: MMU: lockless walking shadow page table Xiao Guangrong
2011-07-06 18:08 ` Marcelo Tosatti
2011-07-06 19:26 ` Xiao Guangrong
2011-07-07 8:18 ` Marcelo Tosatti
2011-06-30 8:26 ` [PATCH v3 17/19] KVM: MMU: reorganize struct kvm_shadow_walk_iterator Xiao Guangrong
2011-06-30 8:27 ` [PATCH v3 18/19] KVM: MMU: mmio page fault support Xiao Guangrong
2011-07-06 18:52 ` Marcelo Tosatti
2011-07-06 19:59 ` Xiao Guangrong
2011-07-07 8:49 ` Marcelo Tosatti
2011-06-30 8:28 ` [PATCH v3 19/19] KVM: MMU: trace mmio page fault Xiao Guangrong
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