From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, kai.huang@linux.intel.com,
jike.song@intel.com
Subject: Re: [PATCH v3 05/11] KVM: page track: introduce kvm_page_track_{add,remove}_page
Date: Fri, 19 Feb 2016 12:37:16 +0100 [thread overview]
Message-ID: <56C6FE6C.5050305@redhat.com> (raw)
In-Reply-To: <1455449503-20993-6-git-send-email-guangrong.xiao@linux.intel.com>
On 14/02/2016 12:31, Xiao Guangrong wrote:
> + /* does tracking count wrap? */
> + WARN_ON((count > 0) && (val + count < val));
This doesn't work, because "val + count" is an int.
> + /* the last tracker has already gone? */
> + WARN_ON((count < 0) && (val < !count));
Also, here any underflow should warn.
You can actually use the fact that val + count is an int like this:
WARN_ON(val + count < 0 || val + count > USHRT_MAX)
and also please return if the warning fires.
> +void kvm_page_track_add_page(struct kvm *kvm, gfn_t gfn,
> + enum kvm_page_track_mode mode)
> +{
> + struct kvm_memslots *slots;
> + struct kvm_memory_slot *slot;
> + int i;
> +
> + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
> + slots = __kvm_memslots(kvm, i);
> +
> + slot = __gfn_to_memslot(slots, gfn);
> + if (!slot)
> + continue;
> +
> + spin_lock(&kvm->mmu_lock);
> + kvm_slot_page_track_add_page_nolock(kvm, slot, gfn, mode);
> + spin_unlock(&kvm->mmu_lock);
> + }
> +}
I don't think it is right to walk all address spaces. The good news is
that you're not using kvm_page_track_{add,remove}_page at all as far as
I can see, so you can just remove them.
Also, when you will need it, I think it's better to move the
spin_lock/spin_unlock pair outside the for loop. With this change,
perhaps it's better to leave it to the caller completely---but I cannot
say until I see the caller.
In the meanwhile, please leave out _nolock from the other functions' name.
Paolo
next prev parent reply other threads:[~2016-02-19 11:37 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-14 11:31 [PATCH v3 00/11] KVM: x86: track guest page access Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 01/11] KVM: MMU: rename has_wrprotected_page to mmu_gfn_lpage_is_disallowed Xiao Guangrong
2016-02-19 11:08 ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 02/11] KVM: MMU: introduce kvm_mmu_gfn_{allow,disallow}_lpage Xiao Guangrong
2016-02-19 11:09 ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 03/11] KVM: MMU: introduce kvm_mmu_slot_gfn_write_protect Xiao Guangrong
2016-02-19 11:18 ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 04/11] KVM: page track: add the framework of guest page tracking Xiao Guangrong
2016-02-19 11:24 ` Paolo Bonzini
2016-02-23 3:57 ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 05/11] KVM: page track: introduce kvm_page_track_{add,remove}_page Xiao Guangrong
2016-02-19 11:37 ` Paolo Bonzini [this message]
2016-02-23 4:18 ` Xiao Guangrong
2016-02-23 14:15 ` Paolo Bonzini
2016-02-19 11:37 ` Paolo Bonzini
2016-02-23 4:18 ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 06/11] KVM: MMU: let page fault handler be aware tracked page Xiao Guangrong
2016-02-19 11:45 ` Paolo Bonzini
2016-02-23 4:19 ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 07/11] KVM: page track: add notifier support Xiao Guangrong
2016-02-19 11:51 ` Paolo Bonzini
2016-02-23 4:34 ` Xiao Guangrong
2016-02-23 14:16 ` Paolo Bonzini
2016-02-14 11:31 ` [PATCH v3 08/11] KVM: MMU: use page track for non-leaf shadow pages Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 09/11] KVM: MMU: simplify mmu_need_write_protect Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 10/11] KVM: MMU: clear write-flooding on the fast path of tracked page Xiao Guangrong
2016-02-19 11:55 ` Paolo Bonzini
2016-02-23 4:36 ` Xiao Guangrong
2016-02-14 11:31 ` [PATCH v3 11/11] KVM: MMU: apply page track notifier Xiao Guangrong
2016-02-19 11:56 ` Paolo Bonzini
2016-02-23 4:40 ` Xiao Guangrong
2016-02-23 14:17 ` Paolo Bonzini
2016-02-19 12:00 ` [PATCH v3 00/11] KVM: x86: track guest page access Paolo Bonzini
2016-02-22 10:05 ` Xiao Guangrong
2016-02-23 3:02 ` Jike Song
2016-02-23 5:44 ` Tian, Kevin
2016-02-23 12:13 ` Paolo Bonzini
2016-02-23 10:01 ` Paolo Bonzini
2016-02-23 11:50 ` Jike Song
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=56C6FE6C.5050305@redhat.com \
--to=pbonzini@redhat.com \
--cc=gleb@kernel.org \
--cc=guangrong.xiao@linux.intel.com \
--cc=jike.song@intel.com \
--cc=kai.huang@linux.intel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).