From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (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 322473C0C for ; Fri, 12 Dec 2025 00:10:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765498210; cv=none; b=DAtwY4/pgqUWXK/llIBPmg7idPqdyNzCWhwV31Y9CLP4YlzyEszVcIgBd/g6iWqVdxcw9bYxhruaDdxKUO0SRyjNcCK0u7BbdHtTjruOzGN/t8OmP05ck37PRdoy35/ilRd3rs0HoH5OD4KFyNMU5rfyRnlk4zpWrB0lYB2c+tk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765498210; c=relaxed/simple; bh=FJs+RBlAyiyyQgafk4cnh7FOnP552iwnbEY62gyq610=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=LvRHI96U2YWUsHIa5kovqQtNsgLphb5Gw+IFhK/K6+WdH66+MmYbIkvV7j10ipwmfNyK20kjNJtp7rM6N4NV5/O6F12C/GhHweV0ODkZusdkRk/E5EK1c2Kc6EfZYT3XsSSRL3Y5LU9g74X6vBFQ4yEyDwSeLIIS4RWtI5bOCzk= 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=209.85.210.202 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-f202.google.com with SMTP id d2e1a72fcca58-7bb2303fe94so674585b3a.3 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=qKcx0J05xZGuvVfMz/u12GiqpzIh15wThjzUS3aqcZuwm0524W9OR75/5d9Aznbx3O 1AIOhXOAOr6Ov1B61Xh2JPP+IsbuqPhg1Et/9law3P57Sy9Ot9apOGxBQuljufCiz+7L qmmbfhXUOXGPqOqOoibYWjxTFsI4b7UNn70uEUyvUJWhevFIcTnhVNNkyqaoy5p+TeWj FyVolAxrTtDm8mXJyd97A7WMyFUgFOf1FKso7sI/5UtGS0M+7zeauBA5ooyyk8324Gnk sa4MlOaTnqC/MF3GhOtahPeI/yH9lnHLqE2KR5oLacJ1EgDvRTMAgld5/Zr7Twb2c6wZ xDrw== X-Forwarded-Encrypted: i=1; AJvYcCV46OQgJMD0GEDB+eHCkfHAnopn3Q0MJyxu4ik8k0koieenPjXKz84Pu89qo0Op/GahNSw=@vger.kernel.org X-Gm-Message-State: AOJu0Yxk2jSJ+6FhM+UkxINdteDdq2oa9n5trYjkCKYFIwGj7c1gec+6 xkb1ZdBVhR/gI8WtnbU8nqmGPRpKSrgJFvAiwQu6QGsXGNP4zbQEb5HE2DTC6wxk7PTlIWc0H1h hqgcFxQ== 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: kvm@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.