From nobody Mon Feb 9 19:26:40 2026 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1EF04335073; Mon, 10 Nov 2025 18:24:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762799098; cv=none; b=DwxI5RJ2kfZm9BU3D9AZ8K1qw6ciYJvp5ayFUdbNen0tjGZJ6bhUFcmgK+Jgt0nQBl6xhEIril1NXbhHLEGBua7n+AU3oMZvd1NHYmWwlIvIVQ36H/EJg+RHU/MxXv7clPkLI76DQiXfAV8zue2hfll3mYaps+LXD2WTg9CpXd0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762799098; c=relaxed/simple; bh=jYFK422XN5sDK4Xy8kxd03KOHseSRDbyhejfWJIw0VI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PAAxNuCHmMdFoCkUHyRMu+YRbq5IpJf8PCCDNLJRrjSXojtE/thB/qoQ/YhY2y7CZFWwexzAn/eS4SFguZ3hmXPQYxhlWLEwfPz4mppGDvEODfd/5I00iDRnP5knerePToWXMqxg0v7m/SBS28EyfEkyVb7mLQSFyqAbNk8AJ0E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Vj1TaIsJ; arc=none smtp.client-ip=198.175.65.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Vj1TaIsJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1762799097; x=1794335097; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jYFK422XN5sDK4Xy8kxd03KOHseSRDbyhejfWJIw0VI=; b=Vj1TaIsJ1jeOujevc6/6D7Z372lGzpXMR2ERdG31TldiBHoZG6iu+slB bOCGbUrdG26obtTLK3HS5+lEoxhQJT8C89PdhM0fSJpUAlB0edOaUaLnI 65+jKK41WDXdaTZJJz/AK8DWv70vvikchg6XSowbxZ8xtVP/gqNOtSQMJ pTlO16ycPake0Px2Dn9bPy451dRyCCqi+T7XsvB4Jo+BcGcdxq54y8oaV RsjCjnQt/UhCu96FgoeMGORk2K3IeVKf+o1XsEaPy/zA2AbTj7CbNdk83 CWP41IfsVHgI20r3bFLjt5HwuqZ+JWH9iv9V4qulBYLhd/C5g32m9ufn4 Q==; X-CSE-ConnectionGUID: tadtMYcHRruXTo3B6EROcg== X-CSE-MsgGUID: 9Kn2Gzf0St2bP5I6+oRTZA== X-IronPort-AV: E=McAfee;i="6800,10657,11609"; a="76305512" X-IronPort-AV: E=Sophos;i="6.19,294,1754982000"; d="scan'208";a="76305512" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Nov 2025 10:24:57 -0800 X-CSE-ConnectionGUID: 4Up46sQJRluOi5ufeHeApQ== X-CSE-MsgGUID: 1xWoI8fFQnipwr6GO8/8ZA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,294,1754982000"; d="scan'208";a="219396175" Received: from chang-linux-3.sc.intel.com (HELO chang-linux-3) ([172.25.66.172]) by orviesa002.jf.intel.com with ESMTP; 10 Nov 2025 10:24:57 -0800 From: "Chang S. Bae" To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: pbonzini@redhat.com, seanjc@google.com, chao.gao@intel.com, zhao1.liu@intel.com, chang.seok.bae@intel.com Subject: [PATCH RFC v1 12/20] KVM: x86: Support REX2-extended register index in the decoder Date: Mon, 10 Nov 2025 18:01:23 +0000 Message-ID: <20251110180131.28264-13-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251110180131.28264-1-chang.seok.bae@intel.com> References: <20251110180131.28264-1-chang.seok.bae@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Update register index decoding to account for the additional bit fields introduced by the REX2 prefix. Both ModR/M and opcode register decoding paths now consider the extended index bits (R4, X4, B4) in addition to the legacy REX bits (R3, X3, B3). Signed-off-by: Chang S. Bae --- arch/x86/kvm/emulate.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 9c98843094a1..ed3a8c0bca20 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1084,7 +1084,8 @@ static void decode_register_operand(struct x86_emulat= e_ctxt *ctxt, reg =3D ctxt->modrm_reg; } else { reg =3D (ctxt->b & 7) | - (ctxt->rex.bits.b3 * BIT(3)); + (ctxt->rex.bits.b3 * BIT(3)) | + (ctxt->rex.bits.b4 * BIT(4)); } =20 if (ctxt->d & Sse) { @@ -1124,9 +1125,12 @@ static int decode_modrm(struct x86_emulate_ctxt *ctx= t, int rc =3D X86EMUL_CONTINUE; ulong modrm_ea =3D 0; =20 - ctxt->modrm_reg =3D ctxt->rex.bits.r3 * BIT(3); - index_reg =3D ctxt->rex.bits.x3 * BIT(3); - base_reg =3D ctxt->rex.bits.b3 * BIT(3); + ctxt->modrm_reg =3D (ctxt->rex.bits.r3 * BIT(3)) | + (ctxt->rex.bits.r4 * BIT(4)); + index_reg =3D (ctxt->rex.bits.x3 * BIT(3)) | + (ctxt->rex.bits.x4 * BIT(4)); + base_reg =3D (ctxt->rex.bits.b3 * BIT(3)) | + (ctxt->rex.bits.b4 * BIT(4)); =20 ctxt->modrm_mod =3D (ctxt->modrm & 0xc0) >> 6; ctxt->modrm_reg |=3D (ctxt->modrm & 0x38) >> 3; --=20 2.51.0