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Thu, 28 May 2020 08:05:10 GMT Received: from b01cxnp22034.gho.pok.ibm.com (b01cxnp22034.gho.pok.ibm.com [9.57.198.24]) by ppma01wdc.us.ibm.com with ESMTP id 316uf8v03e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 28 May 2020 08:05:10 +0000 Received: from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com [9.57.199.110]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 04S859ZW52691258 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 May 2020 08:05:09 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A82D7AE066; Thu, 28 May 2020 08:05:09 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BA267AE05F; Thu, 28 May 2020 08:05:07 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.85.101.128]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 28 May 2020 08:05:07 +0000 (GMT) From: "Aneesh Kumar K.V" To: kvm-ppc@vger.kernel.org, paulus@ozlabs.org Subject: [PATCH] powerpc/book3s64/kvm: Fix secondary page table walk warning during migration Date: Thu, 28 May 2020 13:34:56 +0530 Message-Id: <20200528080456.87797-1-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.687 definitions=2020-05-28_02:2020-05-28, 2020-05-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 mlxscore=0 suspectscore=0 spamscore=0 clxscore=1015 malwarescore=0 lowpriorityscore=0 priorityscore=1501 cotscore=-2147483648 bulkscore=0 mlxlogscore=999 adultscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005280049 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: linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" This patch fix the below warning reported during migration. find_kvm_secondary_pte called with kvm mmu_lock not held CPU: 23 PID: 5341 Comm: qemu-system-ppc Tainted: G W 5.7.0-rc5-kvm-00211-g9ccf10d6d088 #432 NIP: c008000000fe848c LR: c008000000fe8488 CTR: 0000000000000000 REGS: c000001e19f077e0 TRAP: 0700 Tainted: G W (5.7.0-rc5-kvm-00211-g9ccf10d6d088) MSR: 9000000000029033 CR: 42222422 XER: 20040000 CFAR: c00000000012f5ac IRQMASK: 0 GPR00: c008000000fe8488 c000001e19f07a70 c008000000ffe200 0000000000000039 GPR04: 0000000000000001 c000001ffc8b4900 0000000000018840 0000000000000007 GPR08: 0000000000000003 0000000000000001 0000000000000007 0000000000000001 GPR12: 0000000000002000 c000001fff6d9400 000000011f884678 00007fff70b70000 GPR16: 00007fff7137cb90 00007fff7dcb4410 0000000000000001 0000000000000000 GPR20: 000000000ffe0000 0000000000000000 0000000000000001 0000000000000000 GPR24: 8000000000000000 0000000000000001 c000001e1f67e600 c000001e1fd82410 GPR28: 0000000000001000 c000001e2e410000 0000000000000fff 0000000000000ffe NIP [c008000000fe848c] kvmppc_hv_get_dirty_log_radix+0x2e4/0x340 [kvm_hv] LR [c008000000fe8488] kvmppc_hv_get_dirty_log_radix+0x2e0/0x340 [kvm_hv] Call Trace: [c000001e19f07a70] [c008000000fe8488] kvmppc_hv_get_dirty_log_radix+0x2e0/0x340 [kvm_hv] (unreliable) [c000001e19f07b50] [c008000000fd42e4] kvm_vm_ioctl_get_dirty_log_hv+0x33c/0x3c0 [kvm_hv] [c000001e19f07be0] [c008000000eea878] kvm_vm_ioctl_get_dirty_log+0x30/0x50 [kvm] [c000001e19f07c00] [c008000000edc818] kvm_vm_ioctl+0x2b0/0xc00 [kvm] [c000001e19f07d50] [c00000000046e148] ksys_ioctl+0xf8/0x150 [c000001e19f07da0] [c00000000046e1c8] sys_ioctl+0x28/0x80 [c000001e19f07dc0] [c00000000003652c] system_call_exception+0x16c/0x240 [c000001e19f07e20] [c00000000000d070] system_call_common+0xf0/0x278 Instruction dump: 7d3a512a 4200ffd0 7ffefb78 4bfffdc4 60000000 3c820000 e8848468 3c620000 e86384a8 38840010 4800673d e8410018 <0fe00000> 4bfffdd4 60000000 60000000 Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/include/asm/kvm_book3s_64.h | 9 ++++++ arch/powerpc/kvm/book3s_64_mmu_radix.c | 35 ++++++++++++++++++++---- 2 files changed, 38 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h index c58e64a0a74f..cd5bad08b8d3 100644 --- a/arch/powerpc/include/asm/kvm_book3s_64.h +++ b/arch/powerpc/include/asm/kvm_book3s_64.h @@ -635,6 +635,15 @@ extern void kvmhv_remove_nest_rmap_range(struct kvm *kvm, unsigned long gpa, unsigned long hpa, unsigned long nbytes); +static inline pte_t *__find_kvm_secondary_pte(struct kvm *kvm, unsigned long ea, + unsigned *hshift) +{ + pte_t *pte; + + pte = __find_linux_pte(kvm->arch.pgtable, ea, NULL, hshift); + return pte; +} + static inline pte_t *find_kvm_secondary_pte(struct kvm *kvm, unsigned long ea, unsigned *hshift) { diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index 271f1c3d8443..a328db6a5ef8 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -1040,7 +1040,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm, { unsigned long gfn = memslot->base_gfn + pagenum; unsigned long gpa = gfn << PAGE_SHIFT; - pte_t *ptep; + pte_t *ptep, pte; unsigned int shift; int ret = 0; unsigned long old, *rmapp; @@ -1048,12 +1048,35 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm, if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE) return ret; - ptep = find_kvm_secondary_pte(kvm, gpa, &shift); - if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) { - ret = 1; - if (shift) - ret = 1 << (shift - PAGE_SHIFT); + /* + * For performance reason we don't hold kvm->mmu_lock + * while walking the partition scoped table. + */ + ptep = __find_kvm_secondary_pte(kvm, gpa, &shift); + if (!ptep) + return 0; + + pte = READ_ONCE(*ptep); + if (pte_present(pte) && pte_dirty(pte)) { spin_lock(&kvm->mmu_lock); + /* + * Recheck the pte again + */ + if (pte_val(pte) != pte_val(*ptep)) { + /* + * We have KVM_MEM_LOG_DIRTY_PAGES enabled. Hence we + * can only find PAGE_SIZE pte entries here. We can + * continue to use the pte addr returned by above + * page table walk. + */ + if (!pte_present(*ptep) || !pte_dirty(*ptep)) { + spin_unlock(&kvm->mmu_lock); + return 0; + } + } + + ret = 1; + VM_BUG_ON(shift); old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_DIRTY, 0, gpa, shift); kvmppc_radix_tlbie_page(kvm, gpa, shift, kvm->arch.lpid); -- 2.26.2