From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (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 427A54204E for ; Fri, 12 Dec 2025 00:10:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765498211; cv=none; b=GWKpmdTsgxm0blEtW8copUVoxfO5Pz3iuBSZNCSqIwLooJ9AiRmHcQCGBWGkhYhVKbJoyqt82wvlG4S0LLCcNp05cfnJ4jrtvofS6bZvIVHQn1vTvQ3dnOJWu6Kmop710ooJAKA+IOypiayQ51lWVjNYms6n/rRjO75McxexmKc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765498211; c=relaxed/simple; bh=FJs+RBlAyiyyQgafk4cnh7FOnP552iwnbEY62gyq610=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=nw7R+UPdz4zwWSek92MMn8K97zV9rCLUDYKz4wVXEWIbe2mwLKcWPFpl8X40GfKEdh1u8oLKx+DRoWyIl7tUtfHLqJAaPgFH3ilRkJQMwW/q5kFFQexmPSwOYOsfrVOiAuPzBKvjgDIU/hM/gGGWTSovOZlUF2DmC0CfbgEZ+qg= 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=p7mG09sr; arc=none smtp.client-ip=209.85.210.201 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="p7mG09sr" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-7f21951c317so477781b3a.2 for ; Thu, 11 Dec 2025 16:10:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1765498208; x=1766103008; 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=jjUXde3rb7uNgPoaBad26ebGujFjxzQ3pwuIQPIXXcs=; b=p7mG09sr3Rx4NmxhOeAav3NcopT0mvpmgTJKEd6gdlqnia00W6OH7vb3HtcoV/Z7hi 8jxIRkiY7s+XjIxGE9d69/vdpIS7hPMhA04YMjRBZEGf3buAub/FjH9S+jNZAmjF/MZz FA9zmgmnRyc1Vk3iJAC0lrlI4SnpW2Uk+SXTdUQTko/B9jxhZsiC2ylpTZZ3tA30omZ8 5PaVXVzfnckdVDPEr8rwoDErt/lWG3PvNEgpP+MCcDB3w8fXpRj1Vws7oTEs60ejNmaz dlHMBXxLHpB8kwvGTu1SsYJoecUyRooHECiteXvHsjDf/jY2WBdknWP9BQQwNKI1qmfZ vYSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765498208; x=1766103008; 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=jjUXde3rb7uNgPoaBad26ebGujFjxzQ3pwuIQPIXXcs=; b=Tbl3hdtZ3UJJyfxjLCap72MnlcVkUgSxAQJHNXKVN4p3l2yLJ4iAe6Gs8ItOrztta5 ArjIqonpX9YEpCSIXs44Gua4xuAE1s3UFpjPIlP/sM+QsiGR0hALFtkc2/S9QQvfiuAo OokwZyVtkqKFRum+LYyVlftkDmC6YmaML0QgSvqruQ1uXMliT9Iy8lCaCDl8IZGJ6Llb IUJwaVsa9aHLJF6NjKFY66+zJGt/45bgM+p0c1QKk8JE6vPMk0S8MPi5bQvkds7yXVaf RUwWewZvi9591B3cmXOkDvVBk0TrJlgyoHDt15QohAug7BYclrPFh/UHKbY2SUXpcOhq /Qag== X-Forwarded-Encrypted: i=1; AJvYcCVu/DjpoWOL8ppdXv6XQ7aHr1GChvw/zLybduL6zqm6gfPBbgFG0SgDqZR7pKY3F75etlVuwkoO/8Fnd5w=@vger.kernel.org X-Gm-Message-State: AOJu0Yxq7Nl99qgsMh4pbEHrrx2GqogCn4bYTotSl29YJ9sLISeGkiB/ p26h3hvYjsTUxdzGU9j32qMJzarVOxR+CmwdoSx+yyVLw9hR7Ys3WGyxmyTtnlPZQ91GsL0iwfO 1U8T45A== X-Google-Smtp-Source: AGHT+IEf4CdLCUN5qKHl0pCARsahDjmvlGSeTODmkIfIWDeGEqqMbpNSYfg0yOBt/F2QMt2CIks4oSsK158= X-Received: from pfbij11.prod.google.com ([2002:a05:6a00:8ccb:b0:7b8:ba3c:8aeb]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:bb84:b0:7e8:4471:8e4 with SMTP id d2e1a72fcca58-7f66a470cd1mr293793b3a.69.1765498208269; Thu, 11 Dec 2025 16:10:08 -0800 (PST) Date: Thu, 11 Dec 2025 16:10:06 -0800 In-Reply-To: <83cf40c6168c97670193340b00d0fe71a35a6c1b.camel@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251211110024.1409489-1-khushit.shah@nutanix.com> <83cf40c6168c97670193340b00d0fe71a35a6c1b.camel@infradead.org> Message-ID: Subject: Re: [PATCH v4] KVM: x86: Add x2APIC "features" to control EOI broadcast suppression From: Sean Christopherson To: David Woodhouse Cc: Khushit Shah , pbonzini@redhat.com, kai.huang@intel.com, mingo@redhat.com, x86@kernel.org, bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, jon@nutanix.com, shaju.abraham@nutanix.com, stable@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Fri, Dec 12, 2025, David Woodhouse wrote: > On Thu, 2025-12-11 at 10:59 +0000, Khushit Shah wrote: > And my intent was that the in-kernel I/O APIC patch gets included as > *part* of this series, otherwise we're making a semantic change to the > ENABLE behaviour later. Hmm, my only concern on that front is that we'd be backporting effectively new functionality to stable@ kernels that isn't strictly necessary. But that's probably fine given that it requires userspace to opt-in. > Also... how does userspace discover the availability of these flags? Ugh, yeah, I was reading too fast and overlooked that. This needs a CAP.