From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 1AA6B26F2AF for ; Wed, 11 Feb 2026 13:36:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770817007; cv=none; b=XTZ5CmWGLAkSt36VZGNbLu6h22QaJWq216OLtbAEM2p20YZOKLtFvl2oe7cEokqYvZsHRJV2BEZ07pkFR3QjMcjKclz1knRo3KRQW05rU6e/lD0Fa66iGuL98RJBMtUldGc2RLqywXut/C33afH++VZW311Lfm3b1t+9qn2TmZs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770817007; c=relaxed/simple; bh=Ah5LbfpncANcEq/zVhooYt0wsrNtKBkvnVSsoRm6y4o=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=tFxygbcs8nM5InpuJQZTvFinQWCQVukZLyU8ol7Kxd08M7fvH2GGrzP8XNVL5r+57wgMrz+UQy33FfEK+uQ32rS8rE2CKf21sa5KhcXl3LmfiVlsYvGEi68p6hCKnhLtx25PeWXY5N6/ka1F4k+YNOBJ+VInrg8ovbKVI2qcOyk= 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=K0znE1K7; arc=none smtp.client-ip=209.85.214.202 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="K0znE1K7" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2a8c273332cso167503375ad.1 for ; Wed, 11 Feb 2026 05:36:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1770817005; x=1771421805; 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=T07RIz9SdZ2hZEJW4G1VJQ8NJdlmo3HHIX+EMR3i764=; b=K0znE1K7E6L2vHUbsSnr5ra0pNCfmKhObTUKsQB43YZMwj+bjIc5btO8xQv+U1zS9j lbxyUrl6mXi7nlx7O1J2XNnsAcXfrFzehY//NRm0D+exWngKzppVaOBOFWfFiE/NazqH /GCJ87iv2o0dmMkFWhsnsHOZrsSsU8uVUu4iUvezve22oqqsY4Wulr4TvE+QCbkJ0uOp nfSfKVit5brgHSW8QorIXSEsO0u7QRcWtbG/rp30iY1bpx5kAY9WX3xYchJ44NklyOmD OtT7+0ZRkYJ/ZTiR0ngf8oykS1WhcRsU+w3A9n1dY9l/eP9p5Ocx8zGiR/88j09tk6A2 zqVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770817005; x=1771421805; 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=T07RIz9SdZ2hZEJW4G1VJQ8NJdlmo3HHIX+EMR3i764=; b=tO3gvNOeCg5OjoUcBqVaCw7Tvx2a6wXEwNYTHf3snaaT8k5L8PMCbio/xWgzqeIT7r /wxrbWCMz7vCzAmj2+OVn64fEUGBhUUw+MayzcEPptF2sZ1bKBvokctkEVyrX7H+1gkC iCgy+BR48tgH76Em+2IY9HeWHkYn1xnvIm+kvwo2fjXMjafSjcgdSouwKWzOaqmowx0t ptjWGEnlbPsxH22J77lN2qT6EqzMI+ii2mtmyS932gz2PawbudPdcASzyY8olBkXiU+i vTpR1npS17/jYsxwpO2A0vwqzAC0yhuLLgXT2Gom9kUBxFaoGEdRayNNdKZevF4HzQHo vjRw== X-Forwarded-Encrypted: i=1; AJvYcCUEy1FBWFqFTtZRfYTTGn/p0i6NRy8ZaqL07+MiKa37gvTXsX3bErklwtPM7Ig2Wjx1w08XN0vtgHmS3K4=@vger.kernel.org X-Gm-Message-State: AOJu0YyYVJMYPBAi1YmJRfjctImH8+16U5isoxGJK4DbhDtBjdAnBoJU FWt3q+jkl4k/rg1yQ/cH27qFCjl4wiU9EqXB5gY77a2nplZI/AMoFmnl67d6HmOld2JWnayWJDO FW2e1fQ== X-Received: from plbcp16.prod.google.com ([2002:a17:902:e790:b0:29f:68b:3550]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:ac6:b0:2a2:ecb6:55ac with SMTP id d9443c01a7336-2ab275fa5d0mr28639535ad.7.1770817005314; Wed, 11 Feb 2026 05:36:45 -0800 (PST) Date: Wed, 11 Feb 2026 05:36:42 -0800 In-Reply-To: <2af5e3a8-f520-40fd-96a5-28555c3e4a5e@citrix.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260211102928.100944-1-ubizjak@gmail.com> <2af5e3a8-f520-40fd-96a5-28555c3e4a5e@citrix.com> Message-ID: Subject: Re: [PATCH 1/2] KVM: VMX: Drop obsolete branch hint prefixes from inline asm From: Sean Christopherson To: Andrew Cooper Cc: ubizjak@gmail.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@kernel.org, pbonzini@redhat.com, tglx@kernel.org, x86@kernel.org Content-Type: text/plain; charset="us-ascii" On Wed, Feb 11, 2026, Andrew Cooper wrote: > > Remove explicit branch hint prefixes (.byte 0x2e / 0x3e) from VMX > > inline assembly sequences. > > > > These prefixes (CS/DS segment overrides used as branch hints on > > very old x86 CPUs) have been ignored by modern processors for a > > long time. Keeping them provides no measurable benefit and only > > enlarges the generated code. > > It's actually worse than this. > > The branch-taken hint has new meaning in Lion Cove cores and later, > along with a warning saying "performance penalty for misuse". Well that's just lovely. Sounds like maybe this should be tagged for stable@?