From: Sean Christopherson <seanjc@google.com>
To: David Sauerwein <dssauerw@amazon.de>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
"David Woodhouse" <dwmw@amazon.co.uk>,
nh-open-source@amazon.com,
"Jan H. Schönherr" <jschoenh@amazon.de>
Subject: Re: [PATCH] x86: kvm: Initialize static calls before SMP boot
Date: Wed, 4 Mar 2026 11:19:12 -0800 [thread overview]
Message-ID: <aaiFsN3Jn_C5bTnd@google.com> (raw)
In-Reply-To: <20260304165012.13660-1-dssauerw@amazon.de>
On Wed, Mar 04, 2026, David Sauerwein wrote:
> Updating static calls is expensive on wide SMP systems because all
> online CPUs need to act in a coordinated manner for code patching to
> work as expected.
Eww. I am very, very against an early_initcall() in KVM, even if we pinky swear
we'll never use it for anything except prefetching static_call() targets. The
initcall framework lacks the ability to express dependencies, and KVM most definitely
has dependencies on arch and subsys code.
I also don't like hacking KVM to workaround what is effectively a generic
infrastructure issue/limitation.
Have y'all looked at Valentin's series to defer IPIs? I assume/hope deferring
IPIs would reduce the delay observed when doing the patching.
https://lore.kernel.org/all/20251010153839.151763-1-vschneid@redhat.com
next prev parent reply other threads:[~2026-03-04 19:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-04 16:50 [PATCH] x86: kvm: Initialize static calls before SMP boot David Sauerwein
2026-03-04 19:19 ` Sean Christopherson [this message]
2026-03-06 11:19 ` Paolo Bonzini
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