From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 938744BC032; Tue, 4 Aug 2026 20:03:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785873819; cv=none; b=ArsruaNWR75Nv1MQjGkyGiOreKGzs3t/9pNY2gr0s9heFoi+ax7YgdDyyN04tv1H4TljzhRVIFqI33EZz1vAyCR0T3JC+Kh5PCMi6SzOYCzIZ5CfLkMGybmw2a0/aWRFT3yC2n8MOl/6Jb23XnLySR+XHwamjPjYvhwjy4w79Dg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785873819; c=relaxed/simple; bh=9XA8XXE7KJbrVJFdjBJ9tvLZLfG33uEeW/L/jlr0cbE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BDIN9AsRoFYp/Uiju9Ag6cwUmR4E/a9ZJqX4RFGbxFpzVEVXvD1KLXbTBwRcdN45ev3Rnu4C6WV3G23DkzOz54eW81pMbehJ92VKQc+OqOU43lPHJynxpcNHJVwqxAXe4vDP7IYkyQO3WGQiOr8EBRCkLhJaBUb4AaNbOyge1Ic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=bUDc+RRu; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="bUDc+RRu" 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 674JmxPH4117002; Tue, 4 Aug 2026 20:03:28 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=zHvqnC QKRqZ2Sl8eeDO/UCMiuGkLTWRU69qStaN1YsA=; b=bUDc+RRuXfRf8wpwExyOrB etnbU5YTnrm0ybKrIGac8Q6ml7bgWa0bBa7sFQqQzjw15cB586liDrsDgMEgjZYA zw9+wVS5jPudS+tg2APrmtuz4hlOl7PhAHtjQyuM1BaNQ7lC8L31jAWX/oA/xbEG HnhWhh9HLJp4EKPhpM01yP2hh/iDpwSUHH/mRm9m5wI25wltDZ8BaHEQSDAz5ITi caVTtl0UDjwUYsFeiosl6nWGrbnL42Rz5+BVfOUn/QU+z6xWjgZP3eSB2NaTyD4j M+7nEOByYzvqzfgK9VOKL8d5I7hUWiaCB2HvrqCaGX/19i7bfRUCRMwUSUMWjTXA == Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fs8fqqpgy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 04 Aug 2026 20:03:28 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 674JupNo005354; Tue, 4 Aug 2026 20:03:27 GMT Received: from smtprelay02.wdc07v.mail.ibm.com ([172.16.1.69]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4fsugw3nds-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 04 Aug 2026 20:03:27 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (smtpav03.wdc07v.mail.ibm.com [10.39.53.230]) by smtprelay02.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 674K3QWb25821752 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 4 Aug 2026 20:03:26 GMT Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4B65E5805A; Tue, 4 Aug 2026 20:03:26 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2557E58054; Tue, 4 Aug 2026 20:03:25 +0000 (GMT) Received: from [9.61.23.247] (unknown [9.61.23.247]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 4 Aug 2026 20:03:25 +0000 (GMT) Message-ID: Date: Tue, 4 Aug 2026 16:03:24 -0400 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 7/7] KVM: s390: Free guest debug data on vcpu destroy To: Christian Borntraeger , KVM Cc: Janosch Frank , David Hildenbrand , linux-s390 , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Douglas Freimuth References: <20260804162435.28617-1-borntraeger@linux.ibm.com> <20260804162435.28617-8-borntraeger@linux.ibm.com> Content-Language: en-US From: Matthew Rosato In-Reply-To: <20260804162435.28617-8-borntraeger@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: S4ovw_IRBrVWIa_C4O1DTvuUJiH6JlXY X-Proofpoint-ORIG-GUID: S4ovw_IRBrVWIa_C4O1DTvuUJiH6JlXY X-Proofpoint-Spam-Info: AW1haW4tMjYwODA0MDE2MCBTYWx0ZWRfX8IzuVToxzGdH hoXONZsSVrIYLprw99LncZ9WovikgqZhMadL2rbtZBf1ab3mA8VFDeKBv6RBOAsgPNOOiUcYpI4 r4zjSQZGCj6B/rA2ZROlVqQQh8ND8m4= X-Authority-Analysis: v=2.4 cv=K8cS2SWI c=1 sm=1 tr=0 ts=6a724590 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=JkL-GdB9cJYJhCIZ8WwA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA0MDE2MCBTYWx0ZWRfXxZtw7pvkVOJg aq8UE3TWdOtzYeFsfFlwWf3l/YVc4F/jYf5tZ0cTbVS6//pZiZ5gFfZFK+YrUK4dZRSiv/K5uT5 3ddzBbxUVhD33BF4XnS7SOSid8O6vknpHYC+A3P0BaVQ8K9+hahE+deYeOxiLfYXYqRl3oJSuwo m5C9ZxmfI7WzHXgPZ6ke5Z7c+orj1O2vKQh80dwo34eEQxOLZEoY+BDuNuEyyx9rPmZQ0GJo+8c ERzUeXQ2+YsRpywqzl4oNVvWU2DqXfj/wKKzRqwafvslM76lXd4cV16Yn3MG1ywUsklGsPB0ThV g3yeowF13UfE2sRLbQjese7o5ehvaZwzLeWRTXfZtdatqIz1JsR4XY2MkBQkVvLkLysYtx9dAbL vIXnloVkj+BuJFUPfu5OI1qDZwlKaqDFK/Uv6Mei+DX1iCvIfSgDCVEFWWUzmXOdTayXHTM/JMH jvpS0S0XLqtoeqkX3Cw== 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=2026-08-04_05,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 impostorscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 phishscore=0 suspectscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608040160 On 8/4/26 12:24 PM, Christian Borntraeger wrote: > kvm_s390_clear_bp_data() is only called from > kvm_arch_vcpu_ioctl_set_guest_debug(), i.e. when user space changes or > disables debugging. A vCPU that is destroyed while hardware breakpoints > are still armed - the normal case when the VMM just exits or crashes - > leaks hw_bp_info, hw_wp_info and all old_data buffers, since generic KVM > frees the vCPU right after kvm_arch_vcpu_destroy(). > > That is bounded by MAX_BP_COUNT entries, so roughly 8 KiB per vCPU, but > it is unbounded over VM lifetimes. The allocations are > GFP_KERNEL_ACCOUNT, so the charge also outlives the exiting process and > pins dying memcgs. > > Fix by clearing the debug data on vCPU destruction. Calling it > unconditionally is fine: struct kvm_vcpu is zero allocated, so for a vCPU > that never enabled debugging the counters are 0 and the pointers NULL. > > Fixes: 27291e2165b6 ("KVM: s390: hardware support for guest debugging") > Cc: stable@vger.kernel.org > Signed-off-by: Christian Borntraeger Reviewed-by: Matthew Rosato > --- > arch/s390/kvm/kvm-s390.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index e0548926dc49..ccbdb109e22c 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -3409,6 +3409,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) > trace_kvm_s390_destroy_vcpu(vcpu->vcpu_id); > kvm_s390_clear_local_irqs(vcpu); > kvm_clear_async_pf_completion_queue(vcpu); > + kvm_s390_clear_bp_data(vcpu); > if (!kvm_is_ucontrol(vcpu->kvm)) > sca_del_vcpu(vcpu); > kvm_s390_update_topology_change_report(vcpu->kvm, 1);