From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6FEA9CA5FFD for ; Tue, 6 Oct 2026 03:01:45 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4hzLd32fS4z304x; Tue, 06 Oct 2026 14:01:43 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=148.163.156.1 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1791255703; cv=none; b=edM3vHd6zbAF0NTJp4V0C7FpegE/CPfELhjsgBV1+vpb1NKg7hEF0aJdYudJG1rdkd4h6v0GhYHU/+cTTVnXZHwnsEUA/BqFPGkgc5g2Mz9vmQgOtgZrE/O1m2bYXhdu8C58f6UJaDmabXM8V8P3PWxupfFtZ8MaXTNVwc6Nl9+4rlV9PH5RWPos5gj5ioumYkVEyohUdy0jbmc0BddHqjZQFeFtOUrHbBfSRjbQCYTJxiiwRolSaHBIITKvefFSod56ZEwzVUGzIW7k41IZXxYg9L8fxdkeyJ6XrxfGnwcY6V2MERvLmsc9JqgEPs9pDLPMLisybzM67DdmLrb5LA== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1791255703; c=relaxed/relaxed; bh=3tHCZi0tNdUGxWfesBbWABUFMFRLzDxwYBg9AIa/Ec0=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=oA8Kv4Ic5YGxe4paF9Lht/p82JG+y+fnWSuURySvS0+0v3GVvopAqvh9e5ahlr996RrpHvOyqqw7luO+KPgUftBMlu9YjyuZynynGWJbsC39ydVFGGlc2I0Qdxv6MsnA4+y2AaKX2e3ZMiwcDPrsqg4gMIhAUr+MYNk98rSBWnZL/PyMqt6ND0Ms1fdE+Hzr4/A+B0RsXlFfElvqoYdpm95UvOGNZJk1N9nl6l3TzgNa5K7PhBzgm0cEIwWZiw4Tr+LYhtNlY97vcJABtc1RIJjAqMjTe1AhHbnCs+4Je/wFXWxQ7SBMHrBBwjkzxT/JNQ3cvVl6Ld8Y6P902QwU8Q== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=nPE0VVHH; dkim-atps=neutral; spf=pass (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=sshegde@linux.ibm.com; receiver=lists.ozlabs.org) smtp.mailfrom=linux.ibm.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=nPE0VVHH; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=sshegde@linux.ibm.com; receiver=lists.ozlabs.org) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4hzLd15Pd3z2yDm for ; Tue, 06 Oct 2026 14:01:41 +1100 (AEDT) Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 695Haejv3660244; Tue, 6 Oct 2026 03:01:32 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h= content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=3tHCZi 0tNdUGxWfesBbWABUFMFRLzDxwYBg9AIa/Ec0=; b=nPE0VVHH+E0I+PE8ASqXLv H9hbiVJXqpzFIfgw2X9Iw/PHJEyGm594qVueleo4dHeKkf6kz5oh1lxxFgO4aCvB 6eZ3CbhmZWGREfLb706sRDTKJ1G4f6GEuwetBc2qLD7ocjKq5eOFuf97OtGyLi3C h5ZBrmAH6jmzFe6BAlDboCWaYP9yzwjcazvetDctENv5WArkajgZo/tIHb+82iSB FkLnTCBJI4UjIsbAPDEsAJbwCg83rKxemNhPyO5VXc9HOs7HCTqxrAeb4aJ+ydyQ 570L6jhOyZRXkN++JabuAKT1wElXFc0kB30Idseuf3TSaLmLdxOZ52bWmAxs2oTQ == Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4h2scrdmg2-1 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 06 Oct 2026 03:01:31 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.11/8.18.1.11) with ESMTP id 695LpI3k3280960; Tue, 6 Oct 2026 03:01:30 GMT Received: from smtprelay06.fra02v.mail.ibm.com ([9.218.2.230]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4h3dhgr37s-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 06 Oct 2026 03:01:30 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 69631QTc42402184 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 6 Oct 2026 03:01:26 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0958220040; Tue, 6 Oct 2026 03:01:26 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 597352004B; Tue, 6 Oct 2026 03:01:22 +0000 (GMT) Received: from [9.124.213.110] (unknown [9.124.213.110]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 6 Oct 2026 03:01:22 +0000 (GMT) Message-ID: Date: Tue, 6 Oct 2026 08:31:21 +0530 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] KVM: PPC: Book3S HV: Add preempt_disable() around virtual-mode HPTE bit-lock users To: Madhavan Srinivasan , linuxppc-dev@lists.ozlabs.org, Nicholas Piggin , Michael Ellerman , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Gautam Menghani , Harsh Prateek Bora , R Nageswara Sastry , Alexander Graf , linux-hardening@vger.kernel.org, stable@vger.kernel.org, Avi Kivity References: <20260930173750.56759-1-amachhiw@linux.ibm.com> <20260930173750.56759-3-amachhiw@linux.ibm.com> <20261005234024.20213ac7-78-amachhiw@linux.ibm.com> Content-Language: en-US From: Shrikanth Hegde In-Reply-To: <20261005234024.20213ac7-78-amachhiw@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDA2MDAxMCBTYWx0ZWRfXzIrFcDKLio3b BtZ3WnKhtuvm4VaRvPi6Wie5XaRznTT0C4ZrSYmlw1BjODD35oz20abNC73QeQWl1IBs/CWJMnk 5b0YZPPYStB/RzoQ8VwlZWtQOSb0RWA= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDA2MDAxMCBTYWx0ZWRfX7p5qNES/zKzv auvGdkZCWOjqQCSx34p89Er0CvI62GP34su8OZu2VPgudAljoZq9sqeiVYPIZxJ3AbYM8MrReAJ yJJp16O9X7Rzf7lcoIHbPU2Q9da3TbDu0qfEINzCm3TdMFB6Tsj4pP3DK/xTpdeufvBdxBIdTen 8HponTRZ7OMfaNH5MW8at3yjVNt4rkmrhJql4KllBziT9vgQjL7cnKhte7heobTQ7BucybLMUtU JcPwTyDxnCmstPqd41G3M70OFyR/3ngHSzlKRmAzu0+ke9G/COTEflkymfaPmQ7ND2sqlBmbtLy 8DmytLwXu8US63695zTOLUB0JraY2LrKjWvBVtRR7MynX5AIS/65CxDvL3lG4/3lTSSxkVz3r54 OFEwlLK942v/3mkF5WOCU6xGzVo1kZz67bA/TqaBdGFqOB2ywtCQYImF4QxCk/72+DoASp7c8G+ BBmtKXBnlYZwXCld5PA== X-Proofpoint-GUID: 3OSaq9WWDPw38Y2gOSJIk5gwPyhZqYCz X-Proofpoint-ORIG-GUID: qeSoUgWU6eepVwJoT9V5pStS7Vlo_yhX X-Authority-Analysis: v=2.4 cv=B7osQ+tM c=1 sm=1 tr=0 ts=6ac4648b cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=anADAJyGIn8O9P3fJOYA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-05_05,2026-10-05_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 malwarescore=0 impostorscore=0 phishscore=0 clxscore=1015 spamscore=0 adultscore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610060010 On 10/5/26 11:57 PM, Amit Machhiwal wrote: > Hi Shrikanth, > > Thanks for the review. Please find my responses inline below. > >> I don't like this sprinkling of preempt disable/enable. >> Is there not a way to embedd this in try_lock_hpte/unlock_hpte? > > I understand the scattering of preempt_disable()/preempt_enable() looks ugly. > But there are two blockers for that approach: > > 1. The real-mode hcall dispatch table (hcall_real_table in > book3s_hv_rmhandlers.S) calls kvmppc_h_enter(), kvmppc_h_remove(), > kvmppc_h_bulk_remove() and others in book3s_hv_rm_mmu.c, which all call > try_lock_hpte() from real mode. Adding preempt_disable() inside > try_lock_hpte() would affect those real-mode callers, which brings us to your > second point. > Fair enough. Reviewed-by: Shrikanth Hegde