From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Juergen Gross <jgross@suse.com>, Nadav Amit <namit@vmware.com>,
Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Sasha Levin <sashal@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
linux-hyperv@vger.kernel.org,
virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
xen-devel@lists.xenproject.org
Subject: Re: [RFC PATCH 5/6] x86/mm/tlb: Flush remote and local TLBs concurrently
Date: Mon, 27 May 2019 14:45:17 +0200 [thread overview]
Message-ID: <81a67fa3-309d-79cc-5009-5c4908b18ba3@redhat.com> (raw)
In-Reply-To: <20190527123206.GC2623@hirez.programming.kicks-ass.net>
On 27/05/19 14:32, Peter Zijlstra wrote:
> On Mon, May 27, 2019 at 12:21:59PM +0200, Paolo Bonzini wrote:
>> On 27/05/19 11:47, Peter Zijlstra wrote:
>
>>> --- a/arch/x86/kernel/kvm.c
>>> +++ b/arch/x86/kernel/kvm.c
>>> @@ -580,7 +580,7 @@ static void __init kvm_apf_trap_init(voi
>>>
>>> static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
>>>
>>> -static void kvm_flush_tlb_others(const struct cpumask *cpumask,
>>> +static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
>>> const struct flush_tlb_info *info)
>>> {
>>> u8 state;
>>> @@ -594,6 +594,9 @@ static void kvm_flush_tlb_others(const s
>>> * queue flush_on_enter for pre-empted vCPUs
>>> */
>>> for_each_cpu(cpu, flushmask) {
>>> + if (cpu == smp_processor_id())
>>> + continue;
>>> +
>>
>> Even this would be just an optimization; the vCPU you're running on
>> cannot be preempted. You can just change others to multi.
>
> Yeah, I know, but it felt weird so I added the explicit skip. No strong
> feelings though.
Neither here, and it would indeed deserve a comment if you left the if out.
Paolo
next prev parent reply other threads:[~2019-05-27 12:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190525082203.6531-1-namit@vmware.com>
2019-05-25 8:22 ` [RFC PATCH 5/6] x86/mm/tlb: Flush remote and local TLBs concurrently Nadav Amit
2019-05-25 8:38 ` Nadav Amit
2019-05-25 8:54 ` Juergen Gross
2019-05-27 9:47 ` Peter Zijlstra
2019-05-27 10:21 ` Paolo Bonzini
2019-05-27 12:32 ` Peter Zijlstra
2019-05-27 12:45 ` Paolo Bonzini [this message]
2019-05-27 17:49 ` Nadav Amit
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