From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>, Ben Gardon <bgardon@google.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Peter Xu <peterx@redhat.com>, Peter Shier <pshier@google.com>,
Peter Feiner <pfeiner@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 04/24] kvm: x86/mmu: change TDP MMU yield function returns to match cond_resched
Date: Thu, 21 Jan 2021 21:22:09 +0100 [thread overview]
Message-ID: <611654f0-5dcb-b6a2-1b1f-26d10f2b8f7f@redhat.com> (raw)
In-Reply-To: <YAh4q6ZCOw3qDzHP@google.com>
On 20/01/21 19:38, Sean Christopherson wrote:
> Currently the TDP MMU yield / cond_resched functions either return
> nothing or return true if the TLBs were not flushed. These are confusing
> semantics, especially when making control flow decisions in calling
> functions.
>
> To clean things up, change both functions to have the same
> return value semantics as cond_resched: true if the thread yielded,
> false if it did not. If the function yielded in the_flush_ version,
> then the TLBs will have been flushed.
My fault here. The return value was meant to simplify the assignments
below. But it's clearer to return true if the cond_resched happened,
indeed.
>>
>>
>> if (can_yield)
>> - flush_needed = tdp_mmu_iter_flush_cond_resched(kvm, &iter);
>> + flush_needed = !tdp_mmu_iter_flush_cond_resched(kvm,
>> + &iter);
>
> As with the existing code, I'd let this poke out. Alternatively, this could be
> written as:
>
> flush_needed = !can_yield ||
> !tdp_mmu_iter_flush_cond_resched(kvm, &iter);
>
Yeah, no new line here.
Paolo
next prev parent reply other threads:[~2021-01-21 20:24 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 18:10 [PATCH 00/24] Allow parallel page faults with TDP MMU Ben Gardon
2021-01-12 18:10 ` [PATCH 01/24] locking/rwlocks: Add contention detection for rwlocks Ben Gardon
2021-01-12 18:10 ` [PATCH 02/24] sched: Add needbreak " Ben Gardon
2021-01-12 18:10 ` [PATCH 03/24] sched: Add cond_resched_rwlock Ben Gardon
2021-01-12 18:10 ` [PATCH 04/24] kvm: x86/mmu: change TDP MMU yield function returns to match cond_resched Ben Gardon
2021-01-20 18:38 ` Sean Christopherson
2021-01-21 20:22 ` Paolo Bonzini [this message]
2021-01-26 14:11 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 05/24] kvm: x86/mmu: Fix yielding in TDP MMU Ben Gardon
2021-01-20 19:28 ` Sean Christopherson
2021-01-22 1:06 ` Ben Gardon
2021-01-12 18:10 ` [PATCH 06/24] kvm: x86/mmu: Skip no-op changes in TDP MMU functions Ben Gardon
2021-01-20 19:51 ` Sean Christopherson
2021-01-25 23:51 ` Ben Gardon
2021-01-12 18:10 ` [PATCH 07/24] kvm: x86/mmu: Add comment on __tdp_mmu_set_spte Ben Gardon
2021-01-26 14:13 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 08/24] kvm: x86/mmu: Add lockdep when setting a TDP MMU SPTE Ben Gardon
2021-01-20 19:58 ` Sean Christopherson
2021-01-26 14:13 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 09/24] kvm: x86/mmu: Don't redundantly clear TDP MMU pt memory Ben Gardon
2021-01-20 20:06 ` Sean Christopherson
2021-01-26 14:14 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 10/24] kvm: x86/mmu: Factor out handle disconnected pt Ben Gardon
2021-01-20 20:30 ` Sean Christopherson
2021-01-26 14:14 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 11/24] kvm: x86/mmu: Put TDP MMU PT walks in RCU read-critical section Ben Gardon
2021-01-20 22:19 ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 12/24] kvm: x86/kvm: RCU dereference tdp mmu page table links Ben Gardon
2021-01-22 18:32 ` Sean Christopherson
2021-01-26 18:17 ` Ben Gardon
2021-01-12 18:10 ` [PATCH 13/24] kvm: x86/mmu: Only free tdp_mmu pages after a grace period Ben Gardon
2021-01-12 18:10 ` [PATCH 14/24] kvm: mmu: Wrap mmu_lock lock / unlock in a function Ben Gardon
2021-01-12 18:10 ` [PATCH 15/24] kvm: mmu: Wrap mmu_lock cond_resched and needbreak Ben Gardon
2021-01-21 0:19 ` Sean Christopherson
2021-01-21 20:17 ` Paolo Bonzini
2021-01-26 14:38 ` Paolo Bonzini
2021-01-26 17:47 ` Ben Gardon
2021-01-26 17:55 ` Paolo Bonzini
2021-01-26 18:11 ` Ben Gardon
2021-01-26 20:47 ` Paolo Bonzini
2021-01-27 20:08 ` Ben Gardon
2021-01-27 20:55 ` Paolo Bonzini
2021-01-27 21:20 ` Ben Gardon
2021-01-28 8:18 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 16/24] kvm: mmu: Wrap mmu_lock assertions Ben Gardon
2021-01-26 14:29 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 17/24] kvm: mmu: Move mmu_lock to struct kvm_arch Ben Gardon
2021-01-12 18:10 ` [PATCH 18/24] kvm: x86/mmu: Use an rwlock for the x86 TDP MMU Ben Gardon
2021-01-21 0:45 ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 19/24] kvm: x86/mmu: Protect tdp_mmu_pages with a lock Ben Gardon
2021-01-21 19:22 ` Sean Christopherson
2021-01-21 21:32 ` Sean Christopherson
2021-01-26 14:27 ` Paolo Bonzini
2021-01-26 21:47 ` Ben Gardon
2021-01-26 22:02 ` Sean Christopherson
2021-01-26 22:09 ` Sean Christopherson
2021-01-27 12:40 ` Paolo Bonzini
2021-01-26 13:37 ` Paolo Bonzini
2021-01-26 21:07 ` Ben Gardon
2021-01-12 18:10 ` [PATCH 20/24] kvm: x86/mmu: Add atomic option for setting SPTEs Ben Gardon
2021-01-26 14:21 ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 21/24] kvm: x86/mmu: Use atomic ops to set SPTEs in TDP MMU map Ben Gardon
2021-01-12 18:10 ` [PATCH 22/24] kvm: x86/mmu: Flush TLBs after zap in TDP MMU PF handler Ben Gardon
2021-01-21 0:05 ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 23/24] kvm: x86/mmu: Freeze SPTEs in disconnected pages Ben Gardon
2021-01-12 18:10 ` [PATCH 24/24] kvm: x86/mmu: Allow parallel page faults for the TDP MMU Ben Gardon
2021-01-21 0:55 ` Sean Christopherson
2021-01-26 21:57 ` Ben Gardon
2021-01-27 17:14 ` Sean Christopherson
2021-01-26 13:37 ` Paolo Bonzini
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