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 F0E48403AF0 for ; Fri, 12 Jun 2026 23:01:27 +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=1781305289; cv=none; b=eoqoJ+mpQwEJlbc2nQ89phmLC9NiZDFWG1Op3VwmLMsoQY/Hpyv54Cq4Sfj2816X8qbZ0JT4okTI0xePlTHJYX8sYAfgwqUqMbar+A0U9gjZ/T2bx/GJmuWMWQ5c7NWUG1Bi2vJl3D3TD8Gjxr19KnV+EDv7058duDoh0CFeB1w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781305289; c=relaxed/simple; bh=qgWe5MTcj8EpJQ7tU7xrdk/B+H4byiEhpkhWU39nxGc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=dwP2mPQbBNKFn+pkMj2xXyoq7wkkFPlKq3f4wka8NAqHKAJ9at52YUfqE7zNsW1ZNu/d/XipuxFHN+2vUGq8qZevOG+7R6wCKhcr3fDp+R5RE/ZeAgGnjM0zwvMitTRWvQH1HCjj5cuTR6UQx3lCUyFTyMtWxzQVxMwhLttfPRQ= 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=Tt+HY21P; 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="Tt+HY21P" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2c0bf6904a6so23179665ad.1 for ; Fri, 12 Jun 2026 16:01:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1781305287; x=1781910087; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=iJ2P+hwsLw1ZXvxG3VNhmnyf2n1FVoiL6DO6eJPUS/U=; b=Tt+HY21PWbHm2kpTrFd8D4eGGT8EUnwefiAtqxXX4HzJmq9Dv6dpdOCboSZ711Ti1i VVdmnoPfBG45c52pRuqDp+PdWOpnmDnSwWFyiUJyEUizAWRpURD7SNWNLL1HVlWy87PJ kvC51NyccwkOM/N4+DuDdWeBq8jzydkFq6dtRkwmbyjEnqjmxIcE14GqESrTCNydCxc3 vdR6RljG04xb1zz736YoTrRMFOBUqZxkreqNLZB4XQzquWZwroZc90+dIiDO3hE9l+vO yGaDCxi9wmmlJt4xWsjqbt8EG3w+ZdUcR85PAlCPWY0+MPXkYcY/tZHc1rz/II0zyS2c yIpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781305287; x=1781910087; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=iJ2P+hwsLw1ZXvxG3VNhmnyf2n1FVoiL6DO6eJPUS/U=; b=rJm1vUQXXvFKxY5JsvX5NDpg/b/B6x+OirM3aBJthSLkjssMEnHLXDO7xypmzlSmFv 1+uzr0JLO+wn9q8iqAKVmBdwGKH/cqmRgf9veceYP6Zy7RiTBAQA+NeW+TAk5NnYLtEA IbrDAiC+nWHZIyGu9xfNAEfOlDjMF0FLkudolBY0JQWnKgQI1LxTYhLFinIC3fIS+WWk daK9/ZpUdYd2I1UeoRRpBBW49Aki7HlSI/3tqFh7DDn+5QnAET1b4j/6dPRKFZp11Pt/ 9wLj9dmp5oyn7TkGdk7ut4ILUcSfhn7v6cWCZkQF8o4ko312kav/KzKOMvzgWCKAor2L dKGw== X-Forwarded-Encrypted: i=1; AFNElJ/qnR2Jl0j6Zt1rpuxxEPRIxBu8/GMGEF3h3YHpXqCUFc9GlYA8ra2uSARsh6GPQP2OhE8Ob4wRvVSli6Y=@vger.kernel.org X-Gm-Message-State: AOJu0YxGtBOyE19Bww/ohOueByLDv1Dd7S2b93saAeWDtf0DsDXBXQkS l69ayOimBMVxGfGY8ysks84kbLwacNSFPSE94ZnMef/qh3XjoTdYtrOyx40OFPs6Ir7TuxXK5cp Q2vWVeQ== X-Received: from plko4.prod.google.com ([2002:a17:902:6b04:b0:2bf:1a98:5111]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:b0e:b0:2c3:5683:9acb with SMTP id d9443c01a7336-2c412e2203emr55294655ad.32.1781305287229; Fri, 12 Jun 2026 16:01:27 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 12 Jun 2026 16:01:13 -0700 In-Reply-To: <20260612230113.684301-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260612230113.684301-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.1136.gdb2ca164c4-goog Message-ID: <20260612230113.684301-9-seanjc@google.com> Subject: [PATCH v3 8/8] KVM: x86: Read CR4.DE in emulator if and only if accessing DR4 or DR5 From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, "=?UTF-8?q?Carlos=20L=C3=B3pez?=" , "Maciej W . Rozycki" Content-Type: text/plain; charset="UTF-8" Micro-optimize emulation of MOV DR instructions by checking CR4.DE if and only if DR4 or DR5 is being accessed. No functional change intended. Signed-off-by: Sean Christopherson --- arch/x86/kvm/emulate.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index e030ef9b9744..8071b372d233 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3840,13 +3840,11 @@ static int check_dr_read(struct x86_emulate_ctxt *ctxt) { bool is_intel = ctxt->ops->guest_cpuid_is_intel_compatible(ctxt); int dr = ctxt->modrm_reg; - u64 cr4; if (dr > 7) return emulate_ud(ctxt); - cr4 = ctxt->ops->get_cr(ctxt, 4); - if ((cr4 & X86_CR4_DE) && (dr == 4 || dr == 5)) + if ((dr == 4 || dr == 5) && (ctxt->ops->get_cr(ctxt, 4) & X86_CR4_DE)) return emulate_ud(ctxt); /* Intel CPUs prioritize the DR7.GD=1 #DB over the CPL>0 #GP. */ -- 2.54.0.1136.gdb2ca164c4-goog