From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 13D6725A2C2 for ; Fri, 14 Feb 2025 10:27:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739528847; cv=none; b=jHwSALcfAAYw55wZ4O/fGtdDyBcnKV1KMt5id8bkoah92jL39/2CvWN96+z2+fM4Bk87tcnMMsekwQ9YxIfeexrIqg1lDdikGD55snyXxBathhKMfrj4sxVEq5gppqYHswA7ky31Gw+7X5f5/kzDyvbE+x++snt/0i43bRZHDws= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739528847; c=relaxed/simple; bh=78xrz/HVPw8CC87OYPuhUyUhsOxpY1yFErv89zo64dg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KSzkf8G+MLBzWx6f+xBiGCrjMQz2KgHVqJNshemw4UXvJx9cJniSvrqGU7SvAS3qPxQ/JrqwktyiLoeXsWbP3Df99l9UEAbJpstL7fc9RwyibfJOplbNThZFkSDpA7BgR72xng9cH6YO1d7Txjlxicsr+HLI7ofOQ9E55KBnfJ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=O9gwJVr+; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="O9gwJVr+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739528845; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=hZWMT8WxbxzIhhzmDc7Gm/l6y+y9ahJ/5zA846b5VzU=; b=O9gwJVr+csSVQ8gANJbF2G0Ee2b1uwy4ir22KOymBBPc93qgxm0JcsYc/IqrU0AM2Q/K5A jhSAtGJbHtnPc6Ih1eWmwApJb7B09UviPJhul1TXYdRo1n1hcyJi3wIg2eT96w49NRLd+j jLoFO5IVqi50dw+h0SEu0sveDArf7qM= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-303-PHkeqngAOgiTjrBxckxqmA-1; Fri, 14 Feb 2025 05:27:22 -0500 X-MC-Unique: PHkeqngAOgiTjrBxckxqmA-1 X-Mimecast-MFC-AGG-ID: PHkeqngAOgiTjrBxckxqmA_1739528842 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-439605aea5bso10441655e9.1 for ; Fri, 14 Feb 2025 02:27:22 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1739528841; x=1740133641; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=hZWMT8WxbxzIhhzmDc7Gm/l6y+y9ahJ/5zA846b5VzU=; b=ZYfLqoa5wWymtrDZi+WuuPraOTTlgnzXVI2+Aiv9ZApYQJZwY7PFTNLJF893acsb09 tg35AAuF8w8leDjnMmKPo1wkrPPnDhRk62EVm1keAl1Xk35YK1dp3dMihesRMWga5D1h oCn+pu9efhqH8v1Y1HtRpdJ8ITvvbbnfvMr+FCxNAQDK53OLiCCYeWylp6PjfQLiLHTz hz3lMDf9QIjr/LUK/oSMciEXHEXcCeEdM5ARkEpBuDdZ3MFwu0RfUA9bLmG0+I7WCaBd eo/a13tuLo6F7znqoeVbhXA+2XgvkTos8DByWE+OYhkyHQls0ZEteqkeCyHBCkHKSqJd bSqA== X-Gm-Message-State: AOJu0YxKK1gdlLVFbbsHZoqMffKit4vxGxMKDzCLQp5g+FCyS1Sl+573 Ze9mVcpZYyXk4xS9bk8EXv8rZMBhvq2IjkGxiDBfBqJowWSKRoI6zzTerQweE845IW+Cpi9/C5F z0VD6PKKMOg0jpJ5aNEwGZIhzxbAQk4JOJ4aLxiQymxdhpkhqJSFuuOM32tor X-Gm-Gg: ASbGncudowu0KrYdBK8CmxviO2R7vuNI3Ji6hTXDDZtbiO49E8TiRQpqf2APIxUMUUe 75Vtw/oR74VdqHLbRf4WimaMins27ihNjHtzK8TXcXqd+95oTvdfZdNviI5CZ8ttZurEGyVIzoz 7YASWl7iy5WiXINsYsaSaov3FxTGWX+B8DsJ87x1x9tFPmxANLuWVa8PCE4NKxMUQvfLpI3CLlR jyaCswzA+qR6MPckbDnb0kV0CY9hHSnRSNa60gx1PGC4Ic9IzwdsWbR0xCpBK8pYu+mevpUzXQs YCBaghPJrGPDjimpQoXFRdbCXwOzIffMcwrEkBv4s5d2058nbHNjP5EYSFWFgidpchoj5tc/DF4 kgBtJNf2YdHhTyn9LaUFgqWQMHJaMiA== X-Received: by 2002:a05:600c:3d86:b0:439:61cd:4fc3 with SMTP id 5b1f17b1804b1-43961cd52a3mr60414795e9.1.1739528840713; Fri, 14 Feb 2025 02:27:20 -0800 (PST) X-Google-Smtp-Source: AGHT+IGE2/P4K8BMb25jacqE9tesNpiJRwAuk8pmttt4ogltkz1XhcRLH1qgjw26RrtASRE1eojWxA== X-Received: by 2002:a05:600c:3d86:b0:439:61cd:4fc3 with SMTP id 5b1f17b1804b1-43961cd52a3mr60413595e9.1.1739528838802; Fri, 14 Feb 2025 02:27:18 -0800 (PST) Received: from ?IPV6:2003:cb:c709:a00:7d7d:3665:5fe4:7127? (p200300cbc7090a007d7d36655fe47127.dip0.t-ipconnect.de. [2003:cb:c709:a00:7d7d:3665:5fe4:7127]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-439618a9970sm40364945e9.33.2025.02.14.02.27.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Feb 2025 02:27:17 -0800 (PST) Message-ID: Date: Fri, 14 Feb 2025 11:27:15 +0100 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 v1 2/2] KVM: s390: pv: fix race when making a page secure To: Claudio Imbrenda Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com, nrb@linux.ibm.com, seiden@linux.ibm.com, nsg@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com References: <20250213200755.196832-1-imbrenda@linux.ibm.com> <20250213200755.196832-3-imbrenda@linux.ibm.com> <6c741da9-a793-4a59-920f-8df77807bc4d@redhat.com> <20250214111729.000d364e@p-imbrenda> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250214111729.000d364e@p-imbrenda> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14.02.25 11:17, Claudio Imbrenda wrote: > On Thu, 13 Feb 2025 21:16:03 +0100 > David Hildenbrand wrote: > >> On 13.02.25 21:07, Claudio Imbrenda wrote: >>> Holding the pte lock for the page that is being converted to secure is >>> needed to avoid races. A previous commit removed the locking, which >>> caused issues. Fix by locking the pte again. >>> >>> Fixes: 5cbe24350b7d ("KVM: s390: move pv gmap functions into kvm") >> >> If you found this because of my report about the changed locking, >> consider adding a Suggested-by / Reported-y. > > yes, sorry; I sent the patch in haste and forgot. Which one would you > prefer (or both?) > Maybe Reported-by. > [...] > >>> @@ -127,8 +128,11 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) >>> >>> page = gfn_to_page(kvm, gpa_to_gfn(gaddr)); >>> mmap_read_lock(gmap->mm); >>> - if (page) >>> - rc = __gmap_make_secure(gmap, page, uvcb); >>> + vmaddr = gfn_to_hva(gmap->private, gpa_to_gfn(gaddr)); >>> + if (kvm_is_error_hva(vmaddr)) >>> + rc = -ENXIO; >>> + if (!rc && page) >>> + rc = __gmap_make_secure(gmap, page, vmaddr, uvcb); >>> kvm_release_page_clean(page); >>> mmap_read_unlock(gmap->mm); >>> >> >> You effectively make the code more complicated and inefficient than >> before. Now you effectively walk the page table twice in the common >> small-folio case ... > > I think in every case, but see below > >> >> Can we just go back to the old handling that we had before here? >> > > I'd rather not, this is needed to prepare for the next series (for > 6.15) in a couple of weeks, where gmap gets completely removed from > s390/mm, and gmap dat tables will not share ptes with userspace anymore > (i.e. we will use mmu_notifiers, like all other archs) I think for the conversion we would still: GFN -> HVA Walk to the folio mapped at HVA, lock the PTE and perform the conversion. So even with memory notifiers, that should be fine, no? So not necessarily "the old handling that we had before" but rather "the old way of looking up what's mapped and performing the conversion under the PTL". For me to fix the refcount freezing properly on top of your work, we'll need the PTL (esp. to exclude concurrent GUP-slow) etc. -- Cheers, David / dhildenb