From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794061772; b=mGqRsD5uXObea8u1CO1FyKlKhlanJFCFNK7OGUwntv+qbvKUz2nG/FvdQ4rftt6EOs2R 3ckix+xv0vfnh8teYhG0L6p2shzVvheRMBpG7C3uzIHxE1W2mStILXxN8s9qeNs+eoyr0 +Zcvi6zv02ZWA8E4ldqcwyH7+hdNXA+mw6iLAK6o/ZLIo7jsCz+MkNY4ySJJsyLTnM+lB W7pb85Fo/6zjWsna/WANIeC1DMGpt1HhO+E35DAqDMZ/Rn1r0Hd7NJjZuvVMLneSTebLQ M1KXNqcbfQmIhwTkSf+cJ1fJOe7ApPQlvCjbYCySwRIoqaBO2R4QeNNhxSjRvqC4SCw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061772; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=wsNhwjKZpyPo6aDFRc5CZv/6K7uCH1PEUgwJIHd2uEA=; b=RhP0zu8UI/uHG08Eu2CwPkKIm2JbWN2sGLOffuQKz70tPMwxsETT5QUNCa/fvmjxZ/lq pw15aK5Y4OctglkgJkVnNSqKkhTELJBArahZ/L+XB5C0ehknV0Z0f1y/1ViZGyWb9IaSt ClWPkDm7TjUq02e5NRdIQfzjS/6z8G8bScqtyjMjYEBcZNsof9spFXeXA15JDq23728kd g56vxT/BSRBTCDw8K2W729AO6R5wSBLYNwT+flnlCz79a/5ybbpOrFpY92vvwy7y+YnKG VgzyJCvO8gps2M79HYEdYQxDy9cbbBo58Ir25zSs/s3JoQnGgNJVMtCO/ibIkMHDhAA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=vCSbHJE4; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C3684606A32D; Sat, 7 Nov 2026 14:29:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=vCSbHJE4 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6EF611F0089F; Sat, 7 Nov 2026 14:29:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061771; bh=wsNhwjKZpyPo6aDFRc5CZv/6K7uCH1PEUgwJIHd2uEA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=vCSbHJE4oX9gZrrNgLPUstlcqWwRWf248vmc0zMezo6Zv7V2B4icv5XrckBvk00Cp BtdzfCWBhRbojkMbfGoNsq8r9TrctW5A2MIWFqygUdOcZp+92eoG57vw7CrZgnfbUs EBbFMp6yZEBKVsRl+6NiTYSe0Yr6A03c7jB3Iqro= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Amit Machhiwal , Madhavan Srinivasan Subject: [PATCH 6.12 0805/1536] KVM: PPC: Fix get_d_signext() 12-bit displacement for paired-single D-form Date: Sat, 7 Nov 2026 08:47:01 -0500 Message-ID: <20261107135020.156390356@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Amit Machhiwal commit 31895b0ff96778b524c74b43a108090581271603 upstream. get_d_signext() has two compounding bugs since its introduction in 2010: 1. The extraction mask 0x8FF silently drops bits 8-10 of the 12-bit D field (PPC ISA bits 21-23), corrupting any displacement that has any of those bits set. 2. The sign-magnitude idiom "-(d & 0x7ff)" is wrong for two's-complement: for D=0xFFC (encoding of -4) it returns -252 instead of -4. Together these errors produce a wrong effective address for psq_l, psq_lu, psq_st, and psq_stu whenever the displacement is negative or is a positive value >= 0x100 with bits 8-10 set — essentially any real-world paired- single stack-relative access. The D field occupies the bottom 12 bits of the instruction word (confirmed by the adjacent W and I extractions via inst_get_field(inst,16,16) and inst_get_field(inst,17,19)). Replace the open-coded logic with the standard sign_extend32(inst & 0xfff, 11), which correctly performs two's-complement sign extension from 12 bits to 32 bits. Fixes: 831317b605e7 ("KVM: PPC: Implement Paired Single emulation") Cc: stable@vger.kernel.org Signed-off-by: Amit Machhiwal Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260928122837.8782-4-amachhiw@linux.ibm.com Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kvm/book3s_paired_singles.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) --- a/arch/powerpc/kvm/book3s_paired_singles.c +++ b/arch/powerpc/kvm/book3s_paired_singles.c @@ -479,12 +479,7 @@ static bool kvmppc_inst_is_paired_single static int get_d_signext(u32 inst) { - int d = inst & 0x8ff; - - if (d & 0x800) - return -(d & 0x7ff); - - return (d & 0x7ff); + return sign_extend32(inst & 0xfff, 11); } static int kvmppc_ps_three_in(struct kvm_vcpu *vcpu, bool rc,