From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Michael Tokarev <mjt@tls.msk.ru>,
Sven Schnelle <svens@linux.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [PATCH v3 9/9] KVM: Move instrumentation-safe annotations for enter/exit to x86 code
Date: Wed, 21 Apr 2021 10:09:11 +0200 [thread overview]
Message-ID: <0c74158d-279a-5afa-0778-822c77ac8dc2@de.ibm.com> (raw)
In-Reply-To: <20210415222106.1643837-10-seanjc@google.com>
On 16.04.21 00:21, Sean Christopherson wrote:
> Drop the instrumentation_{begin,end}() annonations from the common KVM
> guest enter/exit helpers, and massage the x86 code as needed to preserve
> the necessary annotations. x86 is the only architecture whose transition
> flow is tagged as noinstr, and more specifically, it is the only
> architecture for which instrumentation_{begin,end}() can be non-empty.
>
> No other architecture supports CONFIG_STACK_VALIDATION=y, and s390 is the
> only other architecture that support CONFIG_DEBUG_ENTRY=y. For
> instrumentation annontations to be meaningful, both aformentioned configs
> must be enabled.
>
> Letting x86 deal with the annotations avoids unnecessary nops by
> squashing back-to-back instrumention-safe sequences.
We have considered implementing objtool for s390. Not sure where we
stand and if we will do this or not. Sven/Heiko?
So maybe drop this patch until every other arch agrees that there are
no plans to implement this.
next prev parent reply other threads:[~2021-04-21 8:10 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 22:20 [PATCH v3 0/9] KVM: Fix tick-based accounting for x86 guests Sean Christopherson
2021-04-15 22:20 ` [PATCH v3 1/9] context_tracking: Move guest exit context tracking to separate helpers Sean Christopherson
2021-04-20 18:48 ` Christian Borntraeger
2021-04-21 10:57 ` Frederic Weisbecker
2021-04-15 22:20 ` [PATCH v3 2/9] context_tracking: Move guest exit vtime accounting " Sean Christopherson
2021-04-20 18:48 ` Christian Borntraeger
2021-04-15 22:21 ` [PATCH v3 3/9] KVM: x86: Defer tick-based accounting 'til after IRQ handling Sean Christopherson
2021-04-20 23:14 ` Frederic Weisbecker
2021-04-20 23:26 ` Sean Christopherson
2021-04-21 10:11 ` Frederic Weisbecker
2021-04-21 12:19 ` Frederic Weisbecker
2021-04-28 22:38 ` Sean Christopherson
2021-04-21 10:07 ` Frederic Weisbecker
2021-04-15 22:21 ` [PATCH v3 4/9] sched/vtime: Move vtime accounting external declarations above inlines Sean Christopherson
2021-04-21 7:02 ` Christian Borntraeger
2021-04-15 22:21 ` [PATCH v3 5/9] sched/vtime: Move guest enter/exit vtime accounting to vtime.h Sean Christopherson
2021-04-15 22:21 ` [PATCH v3 6/9] context_tracking: Consolidate guest enter/exit wrappers Sean Christopherson
2021-04-15 22:21 ` [PATCH v3 7/9] context_tracking: KVM: Move guest enter/exit wrappers to KVM's domain Sean Christopherson
2021-04-21 7:10 ` Christian Borntraeger
2021-04-15 22:21 ` [PATCH v3 8/9] KVM: x86: Consolidate guest enter/exit logic to common helpers Sean Christopherson
2021-04-15 22:21 ` [PATCH v3 9/9] KVM: Move instrumentation-safe annotations for enter/exit to x86 code Sean Christopherson
2021-04-21 8:09 ` Christian Borntraeger [this message]
2021-04-22 14:38 ` Sven Schnelle
2021-04-23 9:32 ` Vasily Gorbik
2021-04-20 23:33 ` [PATCH v3 0/9] KVM: Fix tick-based accounting for x86 guests Frederic Weisbecker
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