From: Peter Zijlstra <peterz@infradead.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
mingo@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall\
Date: Mon, 2 Oct 2017 14:48:11 +0200 [thread overview]
Message-ID: <20171002124811.fryss7fdgghuwopg@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <7bef8150-724f-7021-2a7b-cdc3e193b4c9@redhat.com>
On Mon, Oct 02, 2017 at 02:30:33PM +0200, Paolo Bonzini wrote:
> I don't understand why is it correct to delay interrupt injection just
> because VCPU0 is running in a spinlock-protected region? I just cannot
> see the reason why it's safe and not a recipe for priority inversions.
It is indeed not right. Something like:
raw_spin_lock(&some_lock);
/* do crud */
raw_spin_unlock(&some_lock);
Should not hold off the interrupt that tells you your finger is in
imminent danger of becoming detached. Only when we do
local_irq_disable() (ie. raw_spin_lock_irq*() and the like) should we
avoid interrupt delivery.
This whole fixation on spinlock regions is misguided and must stop, its
wrong on all levels.
next prev parent reply other threads:[~2017-10-02 12:48 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-21 11:38 [patch 0/3] KVM KVM_HC_RT_PRIO hypercall support Marcelo Tosatti
2017-09-21 11:38 ` [patch 1/3] KVM: x86: add per-vcpu option to set guest vcpu -RT priority Marcelo Tosatti
2017-09-21 11:38 ` [patch 2/3] KVM: x86: KVM_HC_RT_PRIO hypercall (host-side) Marcelo Tosatti
2017-09-21 13:32 ` Konrad Rzeszutek Wilk
2017-09-21 13:49 ` Paolo Bonzini
2017-09-22 1:08 ` Marcelo Tosatti
2017-09-22 7:23 ` Paolo Bonzini
2017-09-22 12:24 ` Marcelo Tosatti
2017-09-21 11:38 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall Marcelo Tosatti
2017-09-21 13:36 ` Konrad Rzeszutek Wilk
2017-09-21 14:06 ` Peter Zijlstra
2017-09-22 1:10 ` Marcelo Tosatti
2017-09-22 10:00 ` Peter Zijlstra
2017-09-22 10:56 ` Peter Zijlstra
2017-09-22 12:33 ` Marcelo Tosatti
2017-09-22 12:55 ` Peter Zijlstra
2017-09-23 10:56 ` Paolo Bonzini
2017-09-23 13:41 ` Peter Zijlstra
2017-09-24 13:05 ` Paolo Bonzini
2017-09-25 2:57 ` Marcelo Tosatti
2017-09-25 9:13 ` Peter Zijlstra
2017-09-25 15:12 ` Paolo Bonzini
2017-09-26 22:49 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall\ Marcelo Tosatti
2017-09-27 9:37 ` Paolo Bonzini
2017-09-28 0:44 ` Marcelo Tosatti
2017-09-28 7:22 ` Paolo Bonzini
2017-09-28 21:35 ` Marcelo Tosatti
2017-09-28 21:41 ` Marcelo Tosatti
2017-09-29 8:18 ` Paolo Bonzini
2017-09-29 16:40 ` Marcelo Tosatti
2017-09-29 17:05 ` Paolo Bonzini
2017-09-29 20:17 ` Marcelo Tosatti
2017-10-02 12:30 ` Paolo Bonzini
2017-10-02 12:48 ` Peter Zijlstra [this message]
2017-09-26 23:22 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall Marcelo Tosatti
2017-09-25 16:20 ` Konrad Rzeszutek Wilk
2017-09-22 12:16 ` Marcelo Tosatti
2017-09-22 12:31 ` Peter Zijlstra
2017-09-22 12:36 ` Marcelo Tosatti
2017-09-22 12:59 ` Peter Zijlstra
2017-09-25 1:52 ` Marcelo Tosatti
2017-09-25 8:35 ` Peter Zijlstra
2017-09-22 12:40 ` [patch 3/3] x86: kvm guest side support for KVM_HC_RT_PRIO hypercall\ Marcelo Tosatti
2017-09-22 13:01 ` Peter Zijlstra
2017-09-25 2:22 ` Marcelo Tosatti
2017-09-25 8:58 ` Peter Zijlstra
2017-09-25 10:41 ` Thomas Gleixner
2017-09-25 18:28 ` Jan Kiszka
2017-09-21 17:45 ` [patch 0/3] KVM KVM_HC_RT_PRIO hypercall support Jan Kiszka
2017-09-22 1:19 ` Marcelo Tosatti
2017-09-22 6:23 ` Jan Kiszka
2017-09-26 23:59 ` Marcelo Tosatti
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