From: Paolo Bonzini <pbonzini@redhat.com>
To: Ben Gardon <bgardon@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
Peter Xu <peterx@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Peter Shier <pshier@google.com>,
Junaid Shahid <junaids@google.com>,
Jim Mattson <jmattson@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>
Subject: Re: [PATCH v2 0/7] Lazily allocate memslot rmaps
Date: Tue, 4 May 2021 09:21:48 +0200 [thread overview]
Message-ID: <4d27e9d6-42db-3aa1-053a-552e1643f46d@redhat.com> (raw)
In-Reply-To: <CANgfPd-fD33hJkQP_MVb2a4CadKQbkpwwtP9r5rMrC_Mripeqg@mail.gmail.com>
On 03/05/21 19:31, Ben Gardon wrote:
> On Mon, May 3, 2021 at 6:45 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>> On 29/04/21 23:18, Ben Gardon wrote:
>>> This series enables KVM to save memory when using the TDP MMU by waiting
>>> to allocate memslot rmaps until they are needed. To do this, KVM tracks
>>> whether or not a shadow root has been allocated. In order to get away
>>> with not allocating the rmaps, KVM must also be sure to skip operations
>>> which iterate over the rmaps. If the TDP MMU is in use and we have not
>>> allocated a shadow root, these operations would essentially be op-ops
>>> anyway. Skipping the rmap operations has a secondary benefit of avoiding
>>> acquiring the MMU lock in write mode in many cases, substantially
>>> reducing MMU lock contention.
>>>
>>> This series was tested on an Intel Skylake machine. With the TDP MMU off
>>> and on, this introduced no new failures on kvm-unit-tests or KVM selftests.
>>
>> Thanks, I only reported some technicalities in the ordering of loads
>> (which matter since the loads happen with SRCU protection only). Apart
>> from this, this looks fine!
>
> Awesome to hear, thank you for the reviews. Should I send a v3
> addressing those comments, or did you already make those changes when
> applying to your tree?
No, I didn't (I wanted some oversight, and this is 5.14 stuff anyway).
Paolo
next prev parent reply other threads:[~2021-05-04 7:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 21:18 [PATCH v2 0/7] Lazily allocate memslot rmaps Ben Gardon
2021-04-29 21:18 ` [PATCH v2 1/7] KVM: x86/mmu: Track if shadow MMU active Ben Gardon
2021-05-03 13:42 ` Paolo Bonzini
2021-05-04 17:26 ` Ben Gardon
2021-05-04 20:18 ` Paolo Bonzini
2021-05-04 19:55 ` Sean Christopherson
2021-05-04 20:26 ` Paolo Bonzini
2021-05-04 20:36 ` Sean Christopherson
2021-04-29 21:18 ` [PATCH v2 2/7] KVM: x86/mmu: Skip rmap operations if shadow MMU inactive Ben Gardon
2021-04-29 21:18 ` [PATCH v2 3/7] KVM: x86/mmu: Deduplicate rmap freeing Ben Gardon
2021-04-29 21:18 ` [PATCH v2 4/7] KVM: x86/mmu: Factor out allocating memslot rmap Ben Gardon
2021-04-29 21:18 ` [PATCH v2 5/7] KVM: mmu: Refactor memslot copy Ben Gardon
2021-04-29 21:18 ` [PATCH v2 6/7] KVM: mmu: Add slots_arch_lock for memslot arch fields Ben Gardon
2021-05-03 13:29 ` Paolo Bonzini
2021-04-29 21:18 ` [PATCH v2 7/7] KVM: x86/mmu: Lazily allocate memslot rmaps Ben Gardon
2021-05-03 13:42 ` Paolo Bonzini
2021-05-03 17:29 ` Ben Gardon
2021-05-04 20:13 ` Sean Christopherson
2021-05-04 20:19 ` Paolo Bonzini
2021-05-04 20:34 ` Sean Christopherson
2021-05-04 20:22 ` Paolo Bonzini
2021-05-03 13:44 ` [PATCH v2 0/7] " Paolo Bonzini
2021-05-03 17:31 ` Ben Gardon
2021-05-04 7:21 ` Paolo Bonzini [this message]
2021-05-04 17:28 ` Ben Gardon
2021-05-04 18:17 ` Sean Christopherson
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