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Thu, 30 Jul 2026 16:27:16 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 30 Jul 2026 16:27:16 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@kernel.org, seiden@linux.ibm.com, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com Subject: [PATCH v6 12/14] KVM: s390: Fix cleanup in kvm_s390_pv_create_cpu() Date: Thu, 30 Jul 2026 18:27:12 +0200 Message-ID: <20260730162714.133327-13-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730162714.133327-1-imbrenda@linux.ibm.com> References: <20260730162714.133327-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: iSLvBpRm5nHOAa-_Ja9xwp66feeQfJED X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX+A4CNLc7JGkm 37eqB70Qkc61QOH9DNe7WXUeopWrgcDqytEZDYjfXbakzb//ThomGtG5nhHL5j5hpNmw9WXgD3G kgtj61fOI0MOqNC8twkQJCvJmA4WDSvJbh59Bez9GcCoWqryib803MkyusHqxM1sKTTl1oWE6Wo OqFfLAI0v6TwyUbdA/8ELquDHuzAd9rUFC0sPWkU2vsqIQZjWk/MiTSmWiaxJ8siQKPk02hw6AY 6/0fbY1oSZp0T/+CYMz5CfabckMQvFHkpZ5UhH8FMbsWPewc+CaiLJtL/twYtGeEv0aqU2vK5Gu Hr9o3MmeSROsYLzskmDQxD8Y9/F3gtaawEYfgb9KUgVtM3iwXnBvbroBJD9Rj9qAgorjVs5Oll7 CRNXa77neeYla/z7KgAhWfNSsFaPT2IpK58b4ZQ7HoNV24cxA0z0+DZFBrc9lk/sIM975qr4GC5 hpdQytGj8i1uYT3SRBA== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX0RkkvJ4rkA9Y wODszImEUtEI4eyBjveEgG+YjoSOUTH/bfVsSweP5NQGF4fZjcWAj6sjaf0HqgEKUjtrTwa1Kx6 mzkbksLix9X8Rd1XTrvS1AvoBh5t5/g= X-Authority-Analysis: v=2.4 cv=AZeB2XXG c=1 sm=1 tr=0 ts=6a6b7b6c cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=h-RzbZz0cncsEQf3j_AA:9 X-Proofpoint-GUID: iSLvBpRm5nHOAa-_Ja9xwp66feeQfJED X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-30_04,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 phishscore=0 adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 suspectscore=0 lowpriorityscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300123 If creating a protected vCPU in kvm_s390_pv_create_cpu() fails, kvm_s390_pv_destroy_cpu() was called, which checks whether the vCPU has a PV handle and exits doing nothing otherwise. At that point, due to not having created the protected vCPU, the PV handle will not be set, and kvm_s390_pv_destroy_cpu() will do nothing, thus leaking the allocated memory. Fix by factoring out the code to free and reset a PV vCPU; call it from kvm_s390_pv_destroy_cpu() and kvm_s390_pv_create_cpu(). Opportunistically fix the return value of kvm_s390_pv_destroy_cpu() in case of errors: return -EIO instead if EIO. Fixes: d4074324b07a ("KVM: s390: pv: avoid double free of sida page") Signed-off-by: Claudio Imbrenda Reviewed-by: Steffen Eiden --- arch/s390/kvm/pv.c | 41 +++++++++++++++++++++-------------------- 1 file changed, 21 insertions(+), 20 deletions(-) diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c index dc204b521052..b02e0159d3cd 100644 --- a/arch/s390/kvm/pv.c +++ b/arch/s390/kvm/pv.c @@ -244,6 +244,24 @@ static void kvm_s390_clear_pv_state(struct kvm *kvm) kvm->arch.pv.stor_var = NULL; } +static void kvm_s390_pv_dispose_cpu(struct kvm_vcpu *vcpu, bool free_stor_base) +{ + if (free_stor_base) + free_pages(vcpu->arch.pv.stor_base, get_order(uv_info.guest_cpu_stor_len)); + free_page((unsigned long)sida_addr(vcpu->arch.sie_block)); + vcpu->arch.sie_block->pv_handle_cpu = 0; + vcpu->arch.sie_block->pv_handle_config = 0; + memset(&vcpu->arch.pv, 0, sizeof(vcpu->arch.pv)); + vcpu->arch.sie_block->sdf = 0; + /* + * The sidad field (for sdf == 2) is now the gbea field (for sdf == 0). + * Use the reset value of gbea to avoid leaking the kernel pointer of + * the just freed sida. + */ + vcpu->arch.sie_block->gbea = 1; + kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); +} + int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) { int cc; @@ -258,24 +276,9 @@ int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) WARN_ONCE(cc, "protvirt destroy cpu failed rc %x rrc %x", *rc, *rrc); /* Intended memory leak for something that should never happen. */ - if (!cc) - free_pages(vcpu->arch.pv.stor_base, - get_order(uv_info.guest_cpu_stor_len)); - - free_page((unsigned long)sida_addr(vcpu->arch.sie_block)); - vcpu->arch.sie_block->pv_handle_cpu = 0; - vcpu->arch.sie_block->pv_handle_config = 0; - memset(&vcpu->arch.pv, 0, sizeof(vcpu->arch.pv)); - vcpu->arch.sie_block->sdf = 0; - /* - * The sidad field (for sdf == 2) is now the gbea field (for sdf == 0). - * Use the reset value of gbea to avoid leaking the kernel pointer of - * the just freed sida. - */ - vcpu->arch.sie_block->gbea = 1; - kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); + kvm_s390_pv_dispose_cpu(vcpu, !cc); - return cc ? EIO : 0; + return cc ? -EIO : 0; } int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) @@ -319,9 +322,7 @@ int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) uvcb.header.rrc); if (cc) { - u16 dummy; - - kvm_s390_pv_destroy_cpu(vcpu, &dummy, &dummy); + kvm_s390_pv_dispose_cpu(vcpu, true); return -EIO; } -- 2.55.0