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Fri, 27 Mar 2026 15:25:35 +0000 (GMT) Message-ID: <38452644-a097-4e03-a4b9-902c8c8d23f2@linux.ibm.com> Date: Fri, 27 Mar 2026 11:25:35 -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 2/3] KVM: s390: Enable adapter_indicators_set to use mapped pages To: Douglas Freimuth , borntraeger@linux.ibm.com, imbrenda@linux.ibm.com, frankja@linux.ibm.com, david@kernel.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260326014247.2085-1-freimuth@linux.ibm.com> <20260326014247.2085-3-freimuth@linux.ibm.com> Content-Language: en-US From: Matthew Rosato In-Reply-To: <20260326014247.2085-3-freimuth@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: VUcdl6ptUuLAdShsLrZW1ITAXMFYfpCe X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzI3MDEwNSBTYWx0ZWRfX5z5Ft9dAr9ov o5oqZKHPA4BbNjzIDALM7Wt0+ocaOeNhliYUdiSlAcuW/zBnyNUxoa8HAdGkNBr+cfmVQGG40Iu 768Z6Es5Oq0hvg+zStqGf9v18rU2uWYzAsEE2U5/FK5s5xpRuuarHTu9c/1Sl5wrnaUhYWtITFY Hs7Oq4l/0gWGUVkRxt+FFOSePizeSYItA/53AhqlsV6MBhhNh3GWAlpEgeGKxLcU7FBS1mE0avx bswBhimD8x+ghngMPz0ctXGmMBk4pM0wngPEyx4eH/IUyaGfRklyLadEFKR5ewABNVDOixIVwc1 LJM1GWvALmA7P42OhjK7YpM8S/50OPBU3D6+YsVxj4Tt3vk5iL2BOjGoXRzXSgjERARMjfjCYVN Wd6umhzfHETyV6cnsl+HzNUj9nofJ1dF5urhXrab01nnJa8bm36S4uliZ+igBPoujqeQd465zne UhpsZM6Kyf47YuznSZA== X-Proofpoint-GUID: VUcdl6ptUuLAdShsLrZW1ITAXMFYfpCe X-Authority-Analysis: v=2.4 cv=OsZCCi/t c=1 sm=1 tr=0 ts=69c6a172 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=JP7uVcWlml9W1eh-bEUA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-26_04,2026-03-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 clxscore=1015 phishscore=0 suspectscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 spamscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603270105 On 3/25/26 9:42 PM, Douglas Freimuth wrote: > The S390 adapter_indicators_set function needs to be able to use mapped > pages so that worked can be processed,on a fast path when interrupts are > disabled. If adapter indicator pages are not mapped then local mapping is > done on a slow path as it is prior to this patch. For example, Secure > Execution environments will take the local mapping path as it does prior to > this patch. > > Signed-off-by: Douglas Freimuth > --- [...] > static int adapter_indicators_set(struct kvm *kvm, > struct s390_io_adapter *adapter, > struct kvm_s390_adapter_int *adapter_int) > { > unsigned long bit; > int summary_set, idx; > - struct page *ind_page, *summary_page; > + struct s390_map_info *ind_info, *summary_info; > void *map; > + struct page *ind_page, *summary_page; > > - ind_page = get_map_page(kvm, adapter_int->ind_addr); > - if (!ind_page) > - return -1; > - summary_page = get_map_page(kvm, adapter_int->summary_addr); > - if (!summary_page) { > - put_page(ind_page); > - return -1; > + ind_info = get_map_info(adapter, adapter_int->ind_addr); > + if (!ind_info) { > + ind_page = get_map_page(kvm, adapter_int->ind_addr); > + if (!ind_page) > + return -1; > + idx = srcu_read_lock(&kvm->srcu); > + map = page_address(ind_page); > + bit = get_ind_bit(adapter_int->ind_addr, > + adapter_int->ind_offset, adapter->swap); > + set_bit(bit, map); > + mark_page_dirty(kvm, adapter_int->ind_gaddr >> PAGE_SHIFT); > + set_page_dirty_lock(ind_page); Sashiko's comments about this area of code should already be addressed by my comments in v1 wrt to marking the page dirty before unpinning. > + srcu_read_unlock(&kvm->srcu, idx); > + } else { > + map = page_address(ind_info->page); > + bit = get_ind_bit(ind_info->addr, adapter_int->ind_offset, adapter->swap); > + set_bit(bit, map); > + } > + summary_info = get_map_info(adapter, adapter_int->summary_addr); > + if (!summary_info) { > + summary_page = get_map_page(kvm, adapter_int->summary_addr); > + if (!summary_page) { > + put_page(ind_page); Sashiko has a point here. It is possible that you may have taken the else path above where ind_info != NULL and never used ind_page. Initialize ind_page to a NULL value first and check for a NULL value here before attempting a put_page. Or I think you can also check (!ind_info) and only put the page in this case like you do later in this function. [...] > > @@ -2890,6 +2924,7 @@ static int set_adapter_int(struct kvm_kernel_irq_routing_entry *e, > { > int ret; > struct s390_io_adapter *adapter; > + unsigned long flags; > > /* We're only interested in the 0->1 transition. */ > if (!level) > @@ -2897,7 +2932,9 @@ static int set_adapter_int(struct kvm_kernel_irq_routing_entry *e, > adapter = get_io_adapter(kvm, e->adapter.adapter_id); > if (!adapter) > return -1; > + spin_lock_irqsave(&adapter->maps_lock, flags); > ret = adapter_indicators_set(kvm, adapter, &e->adapter); > + spin_unlock_irqrestore(&adapter->maps_lock, flags); Another point for Sashiko -- This is almost certainly a fallout from my recommendation to drop the semaphore from patch 1 and go straight to a spinlock vs adding semaphore in patch 1 and converting in patch 3. You can't put a spinlock here as you may lose control inside adapter_indicators_set. You resolve the incompatibility in the next patch by moving the spinlock inside the call and dropping it before you could lose control -- but you have to already account for that in this patch. > if ((ret > 0) && !adapter->masked) { > ret = kvm_s390_inject_airq(kvm, adapter); > if (ret == 0)