From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E46635F174 for ; Wed, 4 Mar 2026 19:19:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772651956; cv=none; b=Dy62vXjVktmLcoPRkRj4qcs3UO7EHhvgMZ/e2z8Vuk7TLljfFJkkzxkrJ39gRHQtFj+6sovufF6PdOSi377jmH06ib1OmoziUUrE9tL0Tsl8EDT0XDpp8M8Sz4riwosvJ8bYq9bbLyAGCO27PJvcieJwwjBKXmWXi45/HfAHGCQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772651956; c=relaxed/simple; bh=AJfvmOdG9Q7H3f6F7/f1NLYvwstyCEC7CtDarcJ2/2w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Xo8gZp4vBzJpRgHULWE9/fKeub3ryvFyb7nY5F15VfK3itWLpGCrl2tXAgg7kGBWN3BC83okQAXZLPVe0s3hPxsUK/iSGgQPdhPTin75ajIC1pC5qmyvTX6HDtAc2OfZqxcsxdZvOaKWJk7hV3r3dkfEgkqtkAA9FnKCC8+Wsow= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=PyYgxrkW; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="PyYgxrkW" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-358df8fbd1cso6551382a91.0 for ; Wed, 04 Mar 2026 11:19:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1772651954; x=1773256754; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=bT4uLh5T3P+g3RwKfZTTZChmGlh1M0/cVeEK1fku5js=; b=PyYgxrkWq2UncuPuOHJGWG4j0UdmlzZiBnO9P41aNwlsca0UjE54tgIfojZm7U/7Qb 2nz9iKSP7Qo7lnWNlcREzmqdGkxEAwOLX7zUs1PbYpZijZBWc1NOQcKno4FLpRT8DzGv Abypf4aAGIJEb7fENYMK045VVso7k4sf0qeAZkS0PWqoshFjG6aptmDcNYFUSG94ZQ5f jEUXEarnfPCgkEfQZINfCP64GzLy+XVkRheWwSjVd922ulA5ezin97ZhM19IP4VwvQ9/ W1yyut3iZq00VkttM4wklYyZuofnnvgk5LVaSqoRWImFYcZxRWTkrFIg7cJoaVt/+IzI azDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772651954; x=1773256754; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=bT4uLh5T3P+g3RwKfZTTZChmGlh1M0/cVeEK1fku5js=; b=MB8agaKnGpReWS/WBdN3g+hF0dprUi1K2F8NxPGmlcJXFnnthLe2psywAHJhEEtIFP IMI0+LqPdh2emgYnaOtENkT1Site30XwUF+w08zP+DhCeGpQTABbKk62QTMtACRg4dg7 RlfjtAkb7gcijXQHXIbmtnC7b6t9eRZaqhf9YS8pCwtRMdyW8Y4B8EaARky5s7l883QG bWfJAR0V0qauO2a3WSEARw44+u0fIO29NI1oxHUGxe7Tu9+t6gTeoJWE+3YvL0s3hEKJ k7L7FyAWfufWjfMVrHJJWa0J93Ye9I7oesC/We0E6I+uFmn273QWwfUoeDv64iSuITQQ ZmxA== X-Forwarded-Encrypted: i=1; AJvYcCVDfYpAfFbSWVeghWyYAPtA0sL1QPh73pj8gjvqtje1XLTYSJ0TUG8jql2Kb2NK4+idQxM=@vger.kernel.org X-Gm-Message-State: AOJu0Yz3zcc/22Iuo0LVL7RVo+Pf+XJm/z10whcbpth86maGfQzr7Rkm LpT5y49QP5CB4FC76QVaWkJrrt7s/P1HJzAkUCuasyc5Dn7Sfa4rWaRsBYgTQHr2rSmeWUNumlg RjHFDwQ== X-Received: from pjvm12.prod.google.com ([2002:a17:90a:de0c:b0:354:c6d5:9b66]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4fc7:b0:356:7b41:d355 with SMTP id 98e67ed59e1d1-359a69a0346mr2166086a91.1.1772651954103; Wed, 04 Mar 2026 11:19:14 -0800 (PST) Date: Wed, 4 Mar 2026 11:19:12 -0800 In-Reply-To: <20260304165012.13660-1-dssauerw@amazon.de> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260304165012.13660-1-dssauerw@amazon.de> Message-ID: Subject: Re: [PATCH] x86: kvm: Initialize static calls before SMP boot From: Sean Christopherson To: David Sauerwein Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Woodhouse , nh-open-source@amazon.com, "Jan =?utf-8?Q?H=2E_Sch=C3=B6nherr?=" Content-Type: text/plain; charset="us-ascii" 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