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Tue, 05 May 2020 07:18:22 +0000 Received: from b03ledav005.gho.boulder.ibm.com (b03ledav005.gho.boulder.ibm.com [9.17.130.236]) by b03cxnp07029.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 0457ILun61341960 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 5 May 2020 07:18:21 GMT Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9F120BE054; Tue, 5 May 2020 07:18:21 +0000 (GMT) Received: from b03ledav005.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 16641BE04F; Tue, 5 May 2020 07:18:19 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.85.81.70]) by b03ledav005.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 5 May 2020 07:18:18 +0000 (GMT) From: "Aneesh Kumar K.V" To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au Subject: [PATCH v4 15/22] powerpc/kvm/book3s: use find_kvm_host_pte in pute_tce functions Date: Tue, 5 May 2020 12:47:22 +0530 Message-Id: <20200505071729.54912-16-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200505071729.54912-1-aneesh.kumar@linux.ibm.com> References: <20200505071729.54912-1-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-05-05_02:2020-05-04, 2020-05-05 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 spamscore=0 suspectscore=8 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 phishscore=0 mlxscore=0 mlxlogscore=999 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005050053 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Aneesh Kumar K.V" , npiggin@gmail.com, Alexey Kardashevskiy Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Current code just hold rmap lock to ensure parallel page table update is prevented. That is not sufficient. The kernel should also check whether a mmu_notifer callback was running in parallel. Cc: Alexey Kardashevskiy Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/kvm/book3s_64_vio_hv.c | 30 +++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index 6fcaf1fa8e02..acc3ce570be7 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -437,8 +437,8 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, return H_SUCCESS; } -static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu, - unsigned long ua, unsigned long *phpa) +static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu, unsigned long mmu_seq, + unsigned long ua, unsigned long *phpa) { pte_t *ptep, pte; unsigned shift = 0; @@ -452,10 +452,17 @@ static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu, * to exit which will agains result in the below page table walk * to finish. */ - ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift); - if (!ptep || !pte_present(*ptep)) + /* an rmap lock won't make it safe. because that just ensure hash + * page table entries are removed with rmap lock held. After that + * mmu notifier returns and we go ahead and removing ptes from Qemu page table. + */ + ptep = find_kvm_host_pte(vcpu->kvm, mmu_seq, ua, &shift); + if (!ptep) + return -ENXIO; + + pte = READ_ONCE(*ptep); + if (!pte_present(pte)) return -ENXIO; - pte = *ptep; if (!shift) shift = PAGE_SHIFT; @@ -477,10 +484,12 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, unsigned long liobn, unsigned long ioba, unsigned long tce_list, unsigned long npages) { + struct kvm *kvm = vcpu->kvm; struct kvmppc_spapr_tce_table *stt; long i, ret = H_SUCCESS; unsigned long tces, entry, ua = 0; unsigned long *rmap = NULL; + unsigned long mmu_seq; bool prereg = false; struct kvmppc_spapr_tce_iommu_table *stit; @@ -488,6 +497,12 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, if (kvm_is_radix(vcpu->kvm)) return H_TOO_HARD; + /* + * used to check for invalidations in progress + */ + mmu_seq = kvm->mmu_notifier_seq; + smp_rmb(); + stt = kvmppc_find_table(vcpu->kvm, liobn); if (!stt) return H_TOO_HARD; @@ -547,7 +562,9 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, * real page. */ lock_rmap(rmap); - if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) { + + arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); + if (kvmppc_rm_ua_to_hpa(vcpu, mmu_seq, ua, &tces)) { ret = H_TOO_HARD; goto unlock_exit; } @@ -593,6 +610,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, if (rmap) unlock_rmap(rmap); + arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); return ret; } -- 2.26.2