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[2003:cb:c708:9d00:edd9:835b:4bfb:2ce3]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38a1c89e1acsm3629356f8f.68.2024.12.20.01.55.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Dec 2024 01:55:45 -0800 (PST) Message-ID: <0b45aab7-a0d0-4471-b3d1-c50283f19515@redhat.com> Date: Fri, 20 Dec 2024 10:55:44 +0100 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] s390: Convert vsie code to use page->private To: "Matthew Wilcox (Oracle)" , Claudio Imbrenda Cc: linux-mm@kvack.org, linux-s390@vger.kernel.org References: <20241219162252.1025317-1-willy@infradead.org> <20241219162252.1025317-3-willy@infradead.org> 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: <20241219162252.1025317-3-willy@infradead.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 19.12.24 17:22, Matthew Wilcox (Oracle) wrote: > The vsie pages are not standard page tables, so do not convert them to > use ptdesc. They are not page tables "at all" :) A vsie_page is used when emulating hardware virtualization (SIE -- Start Interpretive Executio) for a CPU: vSIE -- virtual SIE These pages primarily hold the shadowed "SIE control block" (SCB) that tells the hardware what to do when entering hardware virtualization (SIE), and include things like CPU state such as registers. We store some other information in the same page. We have to the SCB provided by the VM VCPU when running the nested VM VCPU. The SCB resides in guest physical memory. So similar to shadowing of page tables, we have to detect modifications to the SCB, so we can update out shadowed version accordingly. We use grab a page and fill a vsie page VCPU wants to execute the SIE instruction (executing the nested VM VCPU), and return it to the pool when we are done emulating the SIE instruction. We try to reuse the same vsie pages over various runs, thats why we store the address of the last SCB address we shadowed, to look it up. (improves HW performance) So page->index will hold the "guest physical address of the SCB we shadowed the last time this vsie page was used". We seem to have space in the vsie page, so I think we can avoid messing with page-> completely! From c94e4ecd6ee791ef9cda1c0577a1e765e5ce2867 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 20 Dec 2024 10:53:46 +0100 Subject: [PATCH] tmp Signed-off-by: David Hildenbrand --- arch/s390/kvm/vsie.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index 150b9387860ad..0a8cffe9b80bf 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -46,7 +46,13 @@ struct vsie_page { gpa_t gvrd_gpa; /* 0x0240 */ gpa_t riccbd_gpa; /* 0x0248 */ gpa_t sdnx_gpa; /* 0x0250 */ - __u8 reserved[0x0700 - 0x0258]; /* 0x0258 */ + /* + * guest address of the original SCB. Remains set for free vsie + * pages, so we can properly look them up in our addr_to_page + * radix tree. + */ + gpa_t scb_gpa; /* 0x0258 */ + __u8 reserved[0x0700 - 0x0260]; /* 0x0260 */ struct kvm_s390_crypto_cb crycb; /* 0x0700 */ __u8 fac[S390_ARCH_FAC_LIST_SIZE_BYTE]; /* 0x0800 */ }; @@ -1383,6 +1389,7 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr) page_ref_inc(page); kvm->arch.vsie.pages[kvm->arch.vsie.page_count] = page; kvm->arch.vsie.page_count++; + vsie_page = page_to_virt(page); } else { /* reuse an existing entry that belongs to nobody */ while (true) { @@ -1393,9 +1400,11 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr) kvm->arch.vsie.next++; kvm->arch.vsie.next %= nr_vcpus; } - radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9); + vsie_page = page_to_virt(page); + radix_tree_delete(&kvm->arch.vsie.addr_to_page, + vsie_page->scb_gpa >> 9); } - page->index = addr; + vsie_page->scb_gpa = addr; /* double use of the same address */ if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9, page)) { page_ref_dec(page); @@ -1404,7 +1413,6 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr) } mutex_unlock(&kvm->arch.vsie.mutex); - vsie_page = page_to_virt(page); memset(&vsie_page->scb_s, 0, sizeof(struct kvm_s390_sie_block)); release_gmap_shadow(vsie_page); vsie_page->fault_addr = 0; @@ -1496,7 +1504,8 @@ void kvm_s390_vsie_destroy(struct kvm *kvm) vsie_page = page_to_virt(page); release_gmap_shadow(vsie_page); /* free the radix tree entry */ - radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9); + radix_tree_delete(&kvm->arch.vsie.addr_to_page, + vsie_page->scb_gpa >> 9); __free_page(page); } kvm->arch.vsie.page_count = 0; -- 2.47.1 Howver, page->index is going away so use page->private to > store the address rather than page->index. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > arch/s390/kvm/vsie.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c > index 150b9387860a..26cbd69eb06d 100644 > --- a/arch/s390/kvm/vsie.c > +++ b/arch/s390/kvm/vsie.c > @@ -1393,9 +1393,9 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr) > kvm->arch.vsie.next++; > kvm->arch.vsie.next %= nr_vcpus; > } > - radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9); > + radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->private >> 9); > } > - page->index = addr; > + page->private = addr; > /* double use of the same address */ > if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9, page)) { > page_ref_dec(page); > @@ -1496,7 +1496,7 @@ void kvm_s390_vsie_destroy(struct kvm *kvm) > vsie_page = page_to_virt(page); > release_gmap_shadow(vsie_page); > /* free the radix tree entry */ > - radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9); > + radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->private >> 9); > __free_page(page); > } > kvm->arch.vsie.page_count = 0; -- Cheers, David / dhildenb