From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (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 2C2372F1FC9 for ; Thu, 20 Nov 2025 19:17:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763666249; cv=none; b=GHRQjp5YHJBPz0SZjvAH+5QyEBFPxh3iWWs5S+r0mijG3RDZIBO/8zdjCqsT+PMb0c0TG4KwdW+5gTenkskAhurY6DrEU4h4sGlVQTbuDhGcBv9XFy0fnr4ubcuJSpotjOJz7de8wiwY1WAn6JhocaGAonneptVYy5tn/G12jZc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763666249; c=relaxed/simple; bh=lSF5o0QHgr4nOMFjds/xaNSC9H1MDAf9Kuo3ZhgaGtk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=paLkjGAtKjpU9Ev95Pk5A/jWXRSDOADNu5jOiY44/qYDMQMoIqJ+HoawT8UhQPerzGDEO2ErgsCL/d5WlCDVpnXYz5tsUHXMHX0BowzOycZSAJgg2IDKZNrqmVJxzllilg/4HLQCBw506Tz6ivS7ghlsTJbkVAUW/qFLxq9Oaac= 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=cnAG2fY/; arc=none smtp.client-ip=209.85.128.45 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="cnAG2fY/" Received: by mail-wm1-f45.google.com with SMTP id 5b1f17b1804b1-47775fb6c56so10917365e9.1 for ; Thu, 20 Nov 2025 11:17:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1763666244; x=1764271044; darn=lists.linux.dev; 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=cnAG2fY/t/CzavKyxdlf9IdXsn/E0OsvVoxPNfGvKriypCRjFoVnWkvNlggmvSxEr7 uATWheFodThZ247B1eNK58EoNuG+mvdcA8RUWE4BneuqnA99PPsyChWJzagZBKaPA3i5 ARBvqpb5wmKzVgkaQEz24N0j6vz4H1wKwnaTdXnCPEMAiJg5jZBqqCYwbBUVTVEiXr9h G6M6ygsOjfC2CPJTyCy9E1K+FnRJ1YriGHW/rh2M0KEyjM16YYZRRyzcEyiVR0w+hEP4 oOggctNGfM5/QZUyPnMkJyPvk5w+9WDTQAtSh6cF5sxWGltWsujVQmtecw3CfNFSDmBT MJZA== 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=sVfixDqA3vXP0hoHU2dH0vxpqhKOmIJPGq+a4KjnQWTPA/GJisEYoncer3xT/UcL9t We9ldIhQRJ8kmqG9/p7HacWob1aqUWczMGDGULDlP3fizAddMTqXIKzVVhIh+yZjl4YX ab2jcjjAkil4A+b/O2BznfzB+RNzpxH2C1n+HzcrTWPIDBwuuCxlA5Ehn0z6W4falLQI 74ywp658OhzZBBUB8FM4nHmsWPBrjXZDObqv0SHBs03MRSGtZqarnXEeOqq2YNDXRjw3 Xu07sR2DWCWfVuIAHlM1XYVyoMYrBxmDLMoHDWxvb6xtg/Qgru/lgU8kmzg76+lgnDbQ Uryg== X-Forwarded-Encrypted: i=1; AJvYcCUOE67kk/2dlr3Nbb2swf1YGD8rwDqAxg7CTAbSz9B0hVLqkSmQ/K3gBhz8rrdVv9X4br7dQBuHKCKtO1lIhA==@lists.linux.dev X-Gm-Message-State: AOJu0YyNsoXztU05oreE280OcJHVxf7+lTM9FMno+bZgir8kTXxt/OCs XcegMF51WL+pYZAbL8zSVLF0gPFeIB5hVGDtoHLPW140r/bLD9CXix+W X-Gm-Gg: ASbGnctnAbQZmJBMK0lPZa2OAevpqjsAOxs+WxFLiGiC1Uzt5fclLPJ3tfgKtlaDOxl Qg1vkDGwisbIoFPzABD9xACm2sn9K73VpAhuGz94SLg4DF6O2QsuV06ED/m+3yqdwNLvZ8I98zr KNoEde6ZmYtwWypuzevbHBGcgGpLWpDnid67lxp3zGcU2vO1uzjpJ3jMEAXL+fhpLQcISSvTYWX RfvNg8pqWPqC1Y1GHiILQ2falXYMJCW1cIFJLR+gYOmob6LgL3pr353uAft3SJ05elrcq08CPj6 LCk8N1F+44T1jMe/zqBKDbF+LvhvgPTNoOrYaKSiH/7HVfJIAqRfRBsq7sCsKn4ejFuzMgAEKAh wulCWPtUwzU4fN80kIUsTbEWunJ2I1caSAE6hftc2cLdirGLfiP2JwP2IrJakXEybCQRRsu5okj cPa5j+mUchq2M6Z1ugTeI67g== 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: virtualization@lists.linux.dev 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