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=1793831901; b=hEcYj9n0AOlSOj0pPllP7K0vJl1J51oALcbhrwshJNndhpBUzLDp07LKuOaej0BPd7Re /C2QWZewVPsUlDQJf7veI+vBj7F+oLhNK1R6LB2XHx7951dcTRYnfWv1tf0uqkKFzY+g0 vhPA6tZ1Kgd93ts1ko7qtgzzsUikN+x112VOtnsS7+xqoS/Qu8rEoIPsjPT4CGdYBsoIc tNgAjrnoMgqAClToIxdjWEqLpvlfBWr+qtsvVZPFocr4lDJUyI7ePFscsUIbJQq1JHrUz 7ecxixET8J1VIsJNzd2HdfkH63/BbYeu1MrjmDa+mUOImtxRv37PMMn5nqBXMTtAJaQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831901; 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=m2VjytFovJAMumwqSLWOABSUcHrxQmCbOlO0wgpVscs=; b=aSLobN4cZw2gPBzUCw6azrG6Rgg5wh7HmXWouA6RCMDtIhiY7rNDTqEIf5Hc5YiVTpJ8 uVxudo8Vy2dRhBZD5FheVmk9yxY5j4PBbDfxna2Z4gm7yXyw35pcVYQLKFWto9RFZaV0S 5hC+jm5EcRpJrsN1XWhlw+Yq3vpgfG67ZMGlIg65mHuK+P1gg1DkmartRMeI8F75GWLnZ vlnObTOOAVFGxH0t8wCOl6X5OVQkUdjZB/Fmd8X9JUVt/PyYPR0OReKEjoKtYCflcACy9 9VIVYjEdmx6QZgDisniDu3wb6lG/tMh09mNAG8ulLzBtyUnZQruVVDAGo93O1r3c4rw== 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=2UobyHAe; 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 985F5606A33D; Wed, 4 Nov 2026 22:38:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=2UobyHAe Received: by smtp.kernel.org (Postfix) with ESMTPSA id 303E61F000C1; Wed, 4 Nov 2026 22:38:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831901; bh=m2VjytFovJAMumwqSLWOABSUcHrxQmCbOlO0wgpVscs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2UobyHAeYJ9PchmEjFhAofocUP7JrY4M7PoI/bQw2U2a8M42nHJ2h2wgcTtt9mEip BlseGobmFc3NYeaEp3HeNepaS535NJmYsW5apqy29yar+ak7rt4wRKy/VFNhXHFV/D 3p1foLQwxswop1fNdGk6L/rNHdSFCb2UFyqRiIZM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Amit Machhiwal , Madhavan Srinivasan Subject: [PATCH 6.18 0944/1005] KVM: PPC: Fix get_d_signext() 12-bit displacement for paired-single D-form Date: Wed, 4 Nov 2026 16:11:17 -0500 Message-ID: <20261104211109.556618920@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev 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 6.18-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,