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Fri, 14 Feb 2020 18:40:59 +0000 (UTC) Received: from [10.36.118.137] (unknown [10.36.118.137]) by smtp.corp.redhat.com (Postfix) with ESMTP id 29B965DA7D; Fri, 14 Feb 2020 18:40:56 +0000 (UTC) Subject: Re: [PATCH 11/35] KVM: s390/mm: Make pages accessible before destroying the guest To: Christian Borntraeger , Janosch Frank Cc: KVM , Cornelia Huck , Thomas Huth , Ulrich Weigand , Claudio Imbrenda , Andrea Arcangeli , linux-s390 , Michael Mueller , Vasily Gorbik , linux-mm@kvack.org, Andrew Morton References: <20200207113958.7320-1-borntraeger@de.ibm.com> <20200207113958.7320-12-borntraeger@de.ibm.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: Date: Fri, 14 Feb 2020 19:40:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200207113958.7320-12-borntraeger@de.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 07.02.20 12:39, Christian Borntraeger wrote: > Before we destroy the secure configuration, we better make all > pages accessible again. This also happens during reboot, where we reboot > into a non-secure guest that then can go again into secure mode. As > this "new" secure guest will have a new ID we cannot reuse the old page > state. > > Signed-off-by: Christian Borntraeger > Reviewed-by: Thomas Huth > Reviewed-by: Cornelia Huck > --- > arch/s390/include/asm/pgtable.h | 1 + > arch/s390/kvm/pv.c | 2 ++ > arch/s390/mm/gmap.c | 35 +++++++++++++++++++++++++++++++++ > 3 files changed, 38 insertions(+) > > diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h > index dbd1453e6924..3e2ea997c334 100644 > --- a/arch/s390/include/asm/pgtable.h > +++ b/arch/s390/include/asm/pgtable.h > @@ -1669,6 +1669,7 @@ extern int vmem_remove_mapping(unsigned long start, unsigned long size); > extern int s390_enable_sie(void); > extern int s390_enable_skey(void); > extern void s390_reset_cmma(struct mm_struct *mm); > +extern void s390_reset_acc(struct mm_struct *mm); > > /* s390 has a private copy of get unmapped area to deal with cache synonyms */ > #define HAVE_ARCH_UNMAPPED_AREA > diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c > index 4795e61f4e16..392795a92bd9 100644 > --- a/arch/s390/kvm/pv.c > +++ b/arch/s390/kvm/pv.c > @@ -66,6 +66,8 @@ int kvm_s390_pv_destroy_vm(struct kvm *kvm) > int rc; > u32 ret; > > + /* make all pages accessible before destroying the guest */ > + s390_reset_acc(kvm->mm); > rc = uv_cmd_nodata(kvm_s390_pv_handle(kvm), > UVC_CMD_DESTROY_SEC_CONF, &ret); > WRITE_ONCE(kvm->arch.gmap->guest_handle, 0); > diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c > index 7291452fe5f0..27926a06df32 100644 > --- a/arch/s390/mm/gmap.c > +++ b/arch/s390/mm/gmap.c > @@ -2650,3 +2650,38 @@ void s390_reset_cmma(struct mm_struct *mm) > up_write(&mm->mmap_sem); > } > EXPORT_SYMBOL_GPL(s390_reset_cmma); > + > +/* > + * make inaccessible pages accessible again > + */ > +static int __s390_reset_acc(pte_t *ptep, unsigned long addr, > + unsigned long next, struct mm_walk *walk) > +{ > + pte_t pte = READ_ONCE(*ptep); > + > + if (pte_present(pte)) > + WARN_ON_ONCE(uv_convert_from_secure(pte_val(pte) & PAGE_MASK)); > + return 0; > +} > + > +static const struct mm_walk_ops reset_acc_walk_ops = { > + .pte_entry = __s390_reset_acc, > +}; > + > +#include > +void s390_reset_acc(struct mm_struct *mm) > +{ > + /* > + * we might be called during > + * reset: we walk the pages and clear > + * close of all kvm file descriptors: we walk the pages and clear > + * exit of process on fd closure: vma already gone, do nothing > + */ > + if (!mmget_not_zero(mm)) > + return; > + down_read(&mm->mmap_sem); > + walk_page_range(mm, 0, TASK_SIZE, &reset_acc_walk_ops, NULL); > + up_read(&mm->mmap_sem); > + mmput(mm); > +} > +EXPORT_SYMBOL_GPL(s390_reset_acc); > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb