From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH 2/4] KVM: MMU: support unsync sp out of the protection of 'mmu_lock'
Date: Thu, 23 Sep 2010 11:05:15 +0800 [thread overview]
Message-ID: <4C9AC3EB.1080507@cn.fujitsu.com> (raw)
In-Reply-To: <4C977B9E.6030208@redhat.com>
On 09/20/2010 11:19 PM, Avi Kivity wrote:
> On 09/20/2010 04:19 PM, Xiao Guangrong wrote:
>> It allows keep unsync sp alive while it's out of the protection, later
>> we can use
>> kvm_mmu_free_page() to free it if !sp->active_count
>
> Don't understand. Of course unsync pages exist outside mmu_lock...?
Yes.
sorry, not describe it clear in the log.
>
>
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index 839852d..4b7af3f 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -996,7 +996,6 @@ static void kvm_mmu_free_page(struct kvm *kvm,
>> struct kvm_mmu_page *sp)
>> {
>> ASSERT(is_empty_shadow_page(sp->spt));
>> hlist_del(&sp->hash_link);
>> - list_del(&sp->link);
>> __free_page(virt_to_page(sp->spt));
>> if (!sp->role.direct)
>> __free_page(virt_to_page(sp->gfns));
>> @@ -1681,9 +1680,8 @@ static int kvm_mmu_prepare_zap_page(struct kvm
>> *kvm, struct kvm_mmu_page *sp,
>> kvm_mmu_unlink_parents(kvm, sp);
>> if (!sp->role.invalid&& !sp->role.direct)
>> unaccount_shadowed(kvm, sp->gfn);
>> - if (sp->unsync)
>> - kvm_unlink_unsync_page(kvm, sp);
>> - if (!sp->active_count) {
>> +
>> + if (!sp->active_count || sp->unsync) {
>> /* Count self */
>> ret++;
>> list_move(&sp->link, invalid_list);
>
> How can you drop an active unsync page?
>
> I'm missing something here.
>
Umm, this feature is used like this:
hold mmu_lock
increase sp->active_count
release mmu_lock
......
hold mmu_lock
increase sp->active_count
if (!sp->active_count && sp->invalid)
kvm_mmu_free_page(sp);
......
release mmu_lock
next prev parent reply other threads:[~2010-09-23 3:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-20 14:18 [PATCH 1/4] KVM: MMU: rename 'sp->root_count' to 'sp->active_count' Xiao Guangrong
2010-09-20 14:19 ` [PATCH 2/4] KVM: MMU: support unsync sp out of the protection of 'mmu_lock' Xiao Guangrong
2010-09-20 15:19 ` Avi Kivity
2010-09-23 3:05 ` Xiao Guangrong [this message]
2010-09-26 13:02 ` Avi Kivity
2010-09-20 14:20 ` [PATCH 3/4] KVM: MMU: move reserved bits check to FNAME(update_pte) Xiao Guangrong
2010-09-20 14:21 ` [PATCH 4/4] KVM: MMU: Don't touch unsync sp in kvm_mmu_pte_write() Xiao Guangrong
2010-09-20 15:24 ` Avi Kivity
2010-09-23 2:59 ` Xiao Guangrong
2010-09-26 13:09 ` Avi Kivity
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4C9AC3EB.1080507@cn.fujitsu.com \
--to=xiaoguangrong@cn.fujitsu.com \
--cc=avi@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mtosatti@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.