From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f42.google.com (mail-wm1-f42.google.com [209.85.128.42]) (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 3411C2E6CCB for ; Thu, 20 Nov 2025 19:17:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763666248; cv=none; b=ZwYMms+b/JZ1L+l6SE3KKg/95ONoTwKnDhZnsMGmEbMvTt+yFQZNp4csm67T1IaQrLwqoKc4zGI+K2a6esiL0DHvIJoQKszHFMLWO6DkWyx1C2E7ORWa+fWz/ZMJCvnMF9qAz0buSWlEG3cgOTe/8D3XHcoOw2c1b6Qcvj5ROqw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763666248; c=relaxed/simple; bh=lSF5o0QHgr4nOMFjds/xaNSC9H1MDAf9Kuo3ZhgaGtk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NlKSJYouKcJHjnaq9Hf8GDxxacM7DLfgCL/xIulTIAZ2S9/uXtD8xwvIwFIscOXuVJyUck6IDc3C0bQNPz0rxpirW0Hb/IJqo4CuziBXuyPEHzP7gfPZRKXPijIq1n2XYdrY9BudFIzgISNIHEr2Jmy820YjlJjjsmLqj7/ERDM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=lg41YOye; arc=none smtp.client-ip=209.85.128.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="lg41YOye" Received: by mail-wm1-f42.google.com with SMTP id 5b1f17b1804b1-4779ce2a624so11335515e9.2 for ; Thu, 20 Nov 2025 11:17:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1763666244; x=1764271044; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ZBv4LnZykkOQ/TjccNpluaa1EqrXwtDl05wxHGmZf7c=; b=lg41YOye4Dm+BUUK71Hs3xWtME7YzEBz2oY1dIwbdQ/l5fPpvxXIa0GRM5W8JDG6NL B8JwAl0przYGpGPyxzdrTW+JMzq5+9yxjDz2mZ3rf5ipLDKioY892zgzuOiu2z644TAp 2R0gO1fhwVtMCOdrr8ld7KGtyHg8su8LCQuL7Z2djzF/5gB5rBURU3td9MwdfwjTC7Bl ZgquogETQMsjoKdiCG1YPwuoyMTP8v8i/MmWWXn8wv/fNlVKYSZLfVAAF8P3YXNn1Lbl Smnab0UUyhGE9eKkYLOg61xk9/8COt8qxRHuEFbhZBnEl6rnbUeERVDPWJGPpAEHnwjj vw+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763666244; x=1764271044; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=ZBv4LnZykkOQ/TjccNpluaa1EqrXwtDl05wxHGmZf7c=; b=R9YxjP2PjUGxj1Md7uOTc5COz7Myge9FTHTRjxoDAj+iJL2ecQF7N5Iw3f2X2wtapR 72b1SFAq606Fe4KOkviOITdL4v1QF0Prrvu0tEbRjhBWPI7+aFVt28ofU7J12KaMs8K7 ziC0fGkYdVCqSVATI2vg2AJWUFeXVlluP0NF8JXd4bfH0COFsXM8dPBI3fnM3lZvH44d HMWtDFq/eksHe3AZY/FsqtRVRE9HLyAnBKdrTvxXCAN9MfToFOx6PHirqZDtcYJfb0iD BNM/BoPElEBP4CdlCnGJFpZhTsv6edD5oJcH/xFoxV7U+4f1s/vsVyfaqoZpCXApDraN Lw3Q== X-Forwarded-Encrypted: i=1; AJvYcCWa9ODytshaf1GtTSEhbMnuMCO+QmB5KXib5rLcl4LibYEEv3D6thpNv/Uf2xBrKSOIp4+PoK9NHPoU4fU=@vger.kernel.org X-Gm-Message-State: AOJu0YwKG+g/tSKh6fKU8HERoZ/ZbTMqwSUo8Hdbvi49pn73NxaLkY2m Zgg94g9YmU1p9DHlgN9j/iPPNgE3GDVbhDNcWnZ0MXcL5jMWCKNDPCyl X-Gm-Gg: ASbGncumsfrQywxUM1LJKLkjaNeu9HBvBkYkTtOf/o20XbfGn4Qhb37/qUBphn7HMd6 iN1Jvt3nk2PjuaokTlan0kCtr3OEt3jrm9S2rPbYMX6LSjnhg/BuqZ9gzSUPAwSL1+MyMrPPNk3 Ku83c4aVtRBIKVHZ4hTZ2aoRzmBUA3cFN5fAUUxiWRYTQ53/zXyl4BpyzhkSux0w1Imj/jJS51F l9XC4NHWzHdgajrMQe4AlCYkWkeUVmrsG3lLAeZEKuu+ffFJ2HH+4XQB3VUMT422pCY3A8yD+9+ lqGS5Xi+q1e29Unt/Za1TxNSZF2CqPtspirFgPHEg3UNfbIRI2kyq35FSOujYJZbQNU/T5dqACG b+3QfwqwlwTx4YUDaPNZlotz6sP2QUtbv5ABHOE15ArSHqSlr5Kp0biVDB86HlfYskOtQG9xM5y A0X04E34lhVOsldUtp0GzKYQ== X-Google-Smtp-Source: AGHT+IGVY6pIz9XfoYqA36W2QChb0bpAxGKbTMb270edwXr3H1jsEhq8NuJH02oh2L+7Qe8LHs8RGA== X-Received: by 2002:a05:600c:4685:b0:477:54cd:200e with SMTP id 5b1f17b1804b1-477b8578e58mr41364515e9.1.1763666243780; Thu, 20 Nov 2025 11:17:23 -0800 (PST) Received: from fedora ([46.248.82.114]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42cb7f363b0sm7117884f8f.13.2025.11.20.11.17.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Nov 2025 11:17:23 -0800 (PST) From: Uros Bizjak To: bcm-kernel-feedback-list@broadcom.com, virtualization@lists.linux.dev, x86@kernel.org, linux-kernel@vger.kernel.org Cc: Uros Bizjak , Juergen Gross , Ajay Kaher , Alexey Makhalov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH 2/2] x86/paravirt: Use XOR r32,r32 to clear register in pv_vcpu_is_preempted() Date: Thu, 20 Nov 2025 20:15:57 +0100 Message-ID: <20251120191716.124642-2-ubizjak@gmail.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251120191716.124642-1-ubizjak@gmail.com> References: <20251120191716.124642-1-ubizjak@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit x86_64 zero extends 32bit operations, so for 64bit operands, XOR r32,r32 is functionally equal to XOR r64,r64, but avoids a REX prefix byte when legacy registers are used. Signed-off-by: Uros Bizjak Cc: Juergen Gross Cc: Ajay Kaher Cc: Alexey Makhalov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" --- arch/x86/include/asm/paravirt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 4f6ec60b4cb3..59aec695ae5f 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -577,7 +577,7 @@ static __always_inline void pv_kick(int cpu) static __always_inline bool pv_vcpu_is_preempted(long cpu) { return PVOP_ALT_CALLEE1(bool, lock.vcpu_is_preempted, cpu, - "xor %%" _ASM_AX ", %%" _ASM_AX, + "xor %%eax, %%eax", ALT_NOT(X86_FEATURE_VCPUPREEMPT)); } -- 2.51.1