From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Sean Christopherson <seanjc@google.com>
Cc: dvhart <dvhart@infradead.org>,
"Russell King, ARM Linux" <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Heiko Carstens <hca@linux.ibm.com>, gor <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>,
Oleg Nesterov <oleg@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>, paulmck <paulmck@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>, shuah <shuah@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-csky <linux-csky@vger.kernel.org>,
linux-mips <linux-mips@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
KVM list <kvm@vger.kernel.org>,
linux-kselftest <linux-kselftest@vger.kernel.org>,
Peter Foley <pefoley@google.com>,
Shakeel Butt <shakeelb@google.com>,
Ben Gardon <bgardon@google.com>
Subject: Re: [PATCH v2 4/5] KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs
Date: Fri, 27 Aug 2021 20:06:20 -0400 (EDT) [thread overview]
Message-ID: <1054916754.30218.1630109180443.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <YSlz8h9SWgeuicak@google.com>
----- On Aug 27, 2021, at 7:23 PM, Sean Christopherson seanjc@google.com wrote:
> On Fri, Aug 27, 2021, Mathieu Desnoyers wrote:
[...]
>> Does it reproduce if we randomize the delay to have it picked randomly from 0us
>> to 100us (with 1us step) ? It would remove a lot of the needs for arch-specific
>> magic delay value.
>
> My less-than-scientific testing shows that it can reproduce at delays up to
> ~500us,
> but above ~10us the reproducibility starts to drop. The bug still reproduces
> reliably, it just takes more iterations, and obviously the test runs a bit
> slower.
>
> Any objection to using a 1-10us delay, e.g. a simple usleep((i % 10) + 1)?
Works for me, thanks!
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
WARNING: multiple messages have this Message-ID (diff)
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Sean Christopherson <seanjc@google.com>
Cc: KVM list <kvm@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
linux-kselftest <linux-kselftest@vger.kernel.org>,
Ben Gardon <bgardon@google.com>, shuah <shuah@kernel.org>,
Paul Mackerras <paulus@samba.org>,
linux-s390 <linux-s390@vger.kernel.org>, gor <gor@linux.ibm.com>,
"Russell King, ARM Linux" <linux@armlinux.org.uk>,
linux-csky <linux-csky@vger.kernel.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Ingo Molnar <mingo@redhat.com>, dvhart <dvhart@infradead.org>,
linux-mips <linux-mips@vger.kernel.org>,
Boqun Feng <boqun.feng@gmail.com>, paulmck <paulmck@kernel.org>,
Heiko Carstens <hca@linux.ibm.com>, rostedt <rostedt@goodmis.org>,
Shakeel Butt <shakeelb@google.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Foley <pefoley@google.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Oleg Nesterov <oleg@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v2 4/5] KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs
Date: Fri, 27 Aug 2021 20:06:20 -0400 (EDT) [thread overview]
Message-ID: <1054916754.30218.1630109180443.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <YSlz8h9SWgeuicak@google.com>
----- On Aug 27, 2021, at 7:23 PM, Sean Christopherson seanjc@google.com wrote:
> On Fri, Aug 27, 2021, Mathieu Desnoyers wrote:
[...]
>> Does it reproduce if we randomize the delay to have it picked randomly from 0us
>> to 100us (with 1us step) ? It would remove a lot of the needs for arch-specific
>> magic delay value.
>
> My less-than-scientific testing shows that it can reproduce at delays up to
> ~500us,
> but above ~10us the reproducibility starts to drop. The bug still reproduces
> reliably, it just takes more iterations, and obviously the test runs a bit
> slower.
>
> Any objection to using a 1-10us delay, e.g. a simple usleep((i % 10) + 1)?
Works for me, thanks!
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
WARNING: multiple messages have this Message-ID (diff)
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Sean Christopherson <seanjc@google.com>
Cc: dvhart <dvhart@infradead.org>,
"Russell King, ARM Linux" <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Heiko Carstens <hca@linux.ibm.com>, gor <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>,
Oleg Nesterov <oleg@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>, paulmck <paulmck@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>, shuah <shuah@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-csky <linux-csky@vger.kernel.org>,
linux-mips <linux-mips@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
KVM list <kvm@vger.kernel.org>,
linux-kselftest <linux-kselftest@vger.kernel.org>,
Peter Foley <pefoley@google.com>,
Shakeel Butt <shakeelb@google.com>,
Ben Gardon <bgardon@google.com>
Subject: Re: [PATCH v2 4/5] KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs
Date: Fri, 27 Aug 2021 20:06:20 -0400 (EDT) [thread overview]
Message-ID: <1054916754.30218.1630109180443.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <YSlz8h9SWgeuicak@google.com>
----- On Aug 27, 2021, at 7:23 PM, Sean Christopherson seanjc@google.com wrote:
> On Fri, Aug 27, 2021, Mathieu Desnoyers wrote:
[...]
>> Does it reproduce if we randomize the delay to have it picked randomly from 0us
>> to 100us (with 1us step) ? It would remove a lot of the needs for arch-specific
>> magic delay value.
>
> My less-than-scientific testing shows that it can reproduce at delays up to
> ~500us,
> but above ~10us the reproducibility starts to drop. The bug still reproduces
> reliably, it just takes more iterations, and obviously the test runs a bit
> slower.
>
> Any objection to using a 1-10us delay, e.g. a simple usleep((i % 10) + 1)?
Works for me, thanks!
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-08-28 0:06 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 22:49 [PATCH v2 0/5] KVM: rseq: Fix and a test for a KVM+rseq bug Sean Christopherson
2021-08-20 22:49 ` Sean Christopherson
2021-08-20 22:49 ` Sean Christopherson
2021-08-20 22:49 ` [PATCH v2 1/5] KVM: rseq: Update rseq when processing NOTIFY_RESUME on xfer to KVM guest Sean Christopherson
2021-08-20 22:49 ` Sean Christopherson
2021-08-20 22:49 ` Sean Christopherson
2021-08-23 15:00 ` Mathieu Desnoyers
2021-08-23 15:00 ` Mathieu Desnoyers
2021-08-23 15:00 ` Mathieu Desnoyers
2021-08-20 22:49 ` [PATCH v2 2/5] entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume() Sean Christopherson
2021-08-20 22:49 ` Sean Christopherson
2021-08-20 22:49 ` Sean Christopherson
2021-08-20 22:50 ` [PATCH v2 3/5] tools: Move x86 syscall number fallbacks to .../uapi/ Sean Christopherson
2021-08-20 22:50 ` Sean Christopherson
2021-08-20 22:50 ` Sean Christopherson
2021-08-20 22:50 ` [PATCH v2 4/5] KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs Sean Christopherson
2021-08-20 22:50 ` Sean Christopherson
2021-08-20 22:50 ` Sean Christopherson
2021-08-23 15:18 ` Mathieu Desnoyers
2021-08-23 15:18 ` Mathieu Desnoyers
2021-08-23 15:18 ` Mathieu Desnoyers
2021-08-23 15:20 ` Mathieu Desnoyers
2021-08-23 15:20 ` Mathieu Desnoyers
2021-08-23 15:20 ` Mathieu Desnoyers
2021-08-26 0:51 ` Sean Christopherson
2021-08-26 0:51 ` Sean Christopherson
2021-08-26 0:51 ` Sean Christopherson
2021-08-26 18:42 ` Mathieu Desnoyers
2021-08-26 18:42 ` Mathieu Desnoyers
2021-08-26 18:42 ` Mathieu Desnoyers
2021-08-26 23:54 ` Sean Christopherson
2021-08-26 23:54 ` Sean Christopherson
2021-08-26 23:54 ` Sean Christopherson
2021-08-27 19:09 ` Mathieu Desnoyers
2021-08-27 19:09 ` Mathieu Desnoyers
2021-08-27 19:09 ` Mathieu Desnoyers
2021-08-27 23:23 ` Sean Christopherson
2021-08-27 23:23 ` Sean Christopherson
2021-08-27 23:23 ` Sean Christopherson
2021-08-28 0:06 ` Mathieu Desnoyers [this message]
2021-08-28 0:06 ` Mathieu Desnoyers
2021-08-28 0:06 ` Mathieu Desnoyers
2021-08-20 22:50 ` [PATCH v2 5/5] KVM: selftests: Remove __NR_userfaultfd syscall fallback Sean Christopherson
2021-08-20 22:50 ` Sean Christopherson
2021-08-20 22:50 ` Sean Christopherson
2021-08-23 23:46 ` Ben Gardon
2021-08-23 23:46 ` Ben Gardon
2021-08-23 23:46 ` Ben Gardon
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