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Wed, 7 Oct 2026 18:21:25 +0000 (GMT) Received: from localhost.localdomain (unknown [9.39.25.208]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 7 Oct 2026 18:21:25 +0000 (GMT) From: Amit Machhiwal To: Madhavan Srinivasan , linuxppc-dev@lists.ozlabs.org Cc: Amit Machhiwal , Nicholas Piggin , Michael Ellerman , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , 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 Subject: [PATCH v4 1/3] KVM: PPC: Book3S HV: Add SRCU protection for virtual-mode HPT hcalls Date: Wed, 7 Oct 2026 23:51:13 +0530 Message-ID: <20261007182116.12479-2-amachhiw@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261007182116.12479-1-amachhiw@linux.ibm.com> References: <20261007182116.12479-1-amachhiw@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: w8sOdD_9Q_XMQzvlEmbz-UBTd3Ctkjrr X-Authority-Analysis: v=2.4 cv=KJHPn1Fo c=1 sm=1 tr=0 ts=6ac68db1 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=DgxhUou5BkHipWTGidQA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: QTIGVwiSTBXUnKCONl30bYo-JJZbtQbw X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDA3MDA3MiBTYWx0ZWRfX1YsBmj/13ue/ VRtJ1topMdxoZkK8ZkTY/MTyaH9qiiajgyHAPEgIMQOMimhC/gWRPI1CFbhq/f6dRhvQI5Y5vjc ia/v22zsYkyRZ1jZjW0V/DLL6LhGB/mOyLHJ2XC5fWGgxNsGp8VyPKfF2JrRWOruTyez9bYktm1 PWcZ+pO2cPWOn3Kig9OqsC3KRw5PjEDXOEDNOT1CHeWnfkPuHj0a0i8u9Ms0ztWVpdDmwyTyQvi XagX6oBNRxaJCxLtGD5HXzwoYfyf7YIdrq1j5Vyvw+wxpZan6qD7WfWT1XgfsDEK9deVUEYaouH 8s3EQahMpXk2TfgPb64ITtLj5hJSml37zFhTCcFHO6Ee+OfpSpB0Z0mlsEtR0hVZOTLVO1l/Uqm U9HTuFLB3V+Qxetjx1h4/L/IlCl8XyMVtY0/T872MCFGURP830h9LyK7BvsezGS24RRY5laZiBY n1A7ZJS/8PeABLo5/pQ== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDA3MDA3MiBTYWx0ZWRfX7rkf/yDvQuVd vR7GjA9JB161OOyiy+iFU60pV2/x/lfCLv0QOqbJm8MIf8FCVeuAh10Nrh2THvUAkvz2RAweMfz 3ak5qQzuLNr2prdxNwCujO6tHtEhKq4= 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=2026-10-07_05,2026-10-06_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 impostorscore=0 adultscore=0 clxscore=1015 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610070072 The virtual-mode HPT hcall handlers (H_ENTER, H_REMOVE, H_BULK_REMOVE, H_CLEAR_REF, H_CLEAR_MOD) call into book3s_hv_rm_mmu.c, which accesses memslots via kvm_memslots_raw(). kvm_memslots_raw() uses rcu_dereference_raw_check() to bypass SRCU lockdep annotation checking. This is safe in real mode because the entire guest entry/exit is wrapped in srcu_read_lock/unlock inside kvmppc_run_core() and kvmhv_run_single_vcpu(). However, since commit 6165d5dd99db ("KVM: PPC: Book3S HV: add virtual mode handlers for HPT hcalls and page faults"), these same handlers are also executed in virtual mode via kvmppc_pseries_do_hcall(), which runs after SRCU has already been released on guest exit. A concurrent KVM_SET_USER_MEMORY_REGION deletion or move can therefore call synchronize_srcu_expedited() — which does not wait for this thread — and then kfree(slot) and vfree(slot->arch.rmap) while the hcall handler still holds a raw pointer to the memslot. lock_rmap() then writes to freed vmalloc memory, leading to use-after-free and memory corruption. Because kvm_memslots_raw() suppresses lockdep checks, this race is entirely silent. Fix this by factoring out the 7 HPT hcall handlers (H_REMOVE, H_ENTER, H_READ, H_CLEAR_MOD, H_CLEAR_REF, H_PROTECT, H_BULK_REMOVE) into a helper function, kvmppc_pseries_do_hpt_hcall(), and wrapping its call site in srcu_read_lock(&kvm->srcu) / srcu_read_unlock(&kvm->srcu, idx). Targeting only the HPT hcalls avoids wrapping non-HPT hcalls that sleep (such as H_CONFER, H_REGISTER_VPA, H_PAGE_INIT) or handlers that already acquire SRCU internally (such as H_RTAS). Fixes: 6165d5dd99db ("KVM: PPC: Book3S HV: add virtual mode handlers for HPT hcalls and page faults") Cc: stable@vger.kernel.org # v5.14+ Suggested-by: Ritesh Harjani (IBM) Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Amit Machhiwal --- arch/powerpc/kvm/book3s_hv.c | 70 ++++++++++++++++++------------------ 1 file changed, 35 insertions(+), 35 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index de05d721edc4..46dd550115a4 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1159,6 +1159,38 @@ static long kvmppc_h_rpt_invalidate(struct kvm_vcpu *vcpu, return H_SUCCESS; } +static long kvmppc_pseries_do_hpt_hcall(struct kvm_vcpu *vcpu, unsigned long req) +{ + switch (req) { + case H_REMOVE: + return kvmppc_h_remove(vcpu, kvmppc_get_gpr(vcpu, 4), + kvmppc_get_gpr(vcpu, 5), + kvmppc_get_gpr(vcpu, 6)); + case H_ENTER: + return kvmppc_h_enter(vcpu, kvmppc_get_gpr(vcpu, 4), + kvmppc_get_gpr(vcpu, 5), + kvmppc_get_gpr(vcpu, 6), + kvmppc_get_gpr(vcpu, 7)); + case H_READ: + return kvmppc_h_read(vcpu, kvmppc_get_gpr(vcpu, 4), + kvmppc_get_gpr(vcpu, 5)); + case H_CLEAR_MOD: + return kvmppc_h_clear_mod(vcpu, kvmppc_get_gpr(vcpu, 4), + kvmppc_get_gpr(vcpu, 5)); + case H_CLEAR_REF: + return kvmppc_h_clear_ref(vcpu, kvmppc_get_gpr(vcpu, 4), + kvmppc_get_gpr(vcpu, 5)); + case H_PROTECT: + return kvmppc_h_protect(vcpu, kvmppc_get_gpr(vcpu, 4), + kvmppc_get_gpr(vcpu, 5), + kvmppc_get_gpr(vcpu, 6)); + case H_BULK_REMOVE: + return kvmppc_h_bulk_remove(vcpu); + } + + return H_FUNCTION; +} + int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) { struct kvm *kvm = vcpu->kvm; @@ -1174,47 +1206,15 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) switch (req) { case H_REMOVE: - ret = kvmppc_h_remove(vcpu, kvmppc_get_gpr(vcpu, 4), - kvmppc_get_gpr(vcpu, 5), - kvmppc_get_gpr(vcpu, 6)); - if (ret == H_TOO_HARD) - return RESUME_HOST; - break; case H_ENTER: - ret = kvmppc_h_enter(vcpu, kvmppc_get_gpr(vcpu, 4), - kvmppc_get_gpr(vcpu, 5), - kvmppc_get_gpr(vcpu, 6), - kvmppc_get_gpr(vcpu, 7)); - if (ret == H_TOO_HARD) - return RESUME_HOST; - break; case H_READ: - ret = kvmppc_h_read(vcpu, kvmppc_get_gpr(vcpu, 4), - kvmppc_get_gpr(vcpu, 5)); - if (ret == H_TOO_HARD) - return RESUME_HOST; - break; case H_CLEAR_MOD: - ret = kvmppc_h_clear_mod(vcpu, kvmppc_get_gpr(vcpu, 4), - kvmppc_get_gpr(vcpu, 5)); - if (ret == H_TOO_HARD) - return RESUME_HOST; - break; case H_CLEAR_REF: - ret = kvmppc_h_clear_ref(vcpu, kvmppc_get_gpr(vcpu, 4), - kvmppc_get_gpr(vcpu, 5)); - if (ret == H_TOO_HARD) - return RESUME_HOST; - break; case H_PROTECT: - ret = kvmppc_h_protect(vcpu, kvmppc_get_gpr(vcpu, 4), - kvmppc_get_gpr(vcpu, 5), - kvmppc_get_gpr(vcpu, 6)); - if (ret == H_TOO_HARD) - return RESUME_HOST; - break; case H_BULK_REMOVE: - ret = kvmppc_h_bulk_remove(vcpu); + idx = srcu_read_lock(&kvm->srcu); + ret = kvmppc_pseries_do_hpt_hcall(vcpu, req); + srcu_read_unlock(&kvm->srcu, idx); if (ret == H_TOO_HARD) return RESUME_HOST; break; -- 2.54.0 (Apple Git-157)