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Thu, 30 Apr 2020 07:42:10 +0000 (UTC) Received: from [10.36.113.172] (ovpn-113-172.ams2.redhat.com [10.36.113.172]) by smtp.corp.redhat.com (Postfix) with ESMTP id C98415D9F1; Thu, 30 Apr 2020 07:42:08 +0000 (UTC) Subject: Re: [PATCH v3 08/10] s390x: smp: Wait for sigp completion To: Janosch Frank , kvm@vger.kernel.org Cc: thuth@redhat.com, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, cohuck@redhat.com References: <20200429143518.1360468-1-frankja@linux.ibm.com> <20200429143518.1360468-9-frankja@linux.ibm.com> <6fb43d45-952e-f66b-a0b2-19d8c3f44cd5@redhat.com> <68e16d1a-8990-0160-307d-93e870338879@linux.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: Thu, 30 Apr 2020 09:42:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <68e16d1a-8990-0160-307d-93e870338879@linux.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 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 30.04.20 09:40, Janosch Frank wrote: > On 4/29/20 5:15 PM, David Hildenbrand wrote: >> On 29.04.20 16:35, Janosch Frank wrote: >>> Sigp orders are not necessarily finished when the processor finished >>> the sigp instruction. We need to poll if the order has been finished >>> before we continue. >>> >>> For (re)start and stop we already use sigp sense running and sigp >>> sense loops. But we still lack completion checks for stop and store >>> status, as well as the cpu resets. >>> >>> Let's add them. >>> >>> KVM currently needs a workaround for the stop and store status test, >>> since KVM's SIGP Sense implementation doesn't honor pending SIGPs at >>> it should. Hopefully we can fix that in the future. >>> >>> Signed-off-by: Janosch Frank >>> Reviewed-by: Cornelia Huck >>> --- >>> lib/s390x/smp.c | 9 +++++++++ >>> lib/s390x/smp.h | 1 + >>> s390x/smp.c | 12 ++++++++++-- >>> 3 files changed, 20 insertions(+), 2 deletions(-) >>> >>> diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c >>> index 6ef0335..8628a3d 100644 >>> --- a/lib/s390x/smp.c >>> +++ b/lib/s390x/smp.c >>> @@ -49,6 +49,14 @@ struct cpu *smp_cpu_from_addr(uint16_t addr) >>> return NULL; >>> } >>> >>> +void smp_cpu_wait_for_completion(uint16_t addr) >>> +{ >>> + uint32_t status; >>> + >>> + /* Loops when cc == 2, i.e. when the cpu is busy with a sigp order */ >>> + sigp_retry(1, SIGP_SENSE, 0, &status); >>> +} >>> + >>> bool smp_cpu_stopped(uint16_t addr) >>> { >>> uint32_t status; >>> @@ -100,6 +108,7 @@ int smp_cpu_stop_store_status(uint16_t addr) >>> >>> spin_lock(&lock); >>> rc = smp_cpu_stop_nolock(addr, true); >>> + smp_cpu_wait_for_completion(addr); >>> spin_unlock(&lock); >>> return rc; >>> } >>> diff --git a/lib/s390x/smp.h b/lib/s390x/smp.h >>> index ce63a89..a8b98c0 100644 >>> --- a/lib/s390x/smp.h >>> +++ b/lib/s390x/smp.h >>> @@ -45,6 +45,7 @@ int smp_cpu_restart(uint16_t addr); >>> int smp_cpu_start(uint16_t addr, struct psw psw); >>> int smp_cpu_stop(uint16_t addr); >>> int smp_cpu_stop_store_status(uint16_t addr); >>> +void smp_cpu_wait_for_completion(uint16_t addr); >>> int smp_cpu_destroy(uint16_t addr); >>> int smp_cpu_setup(uint16_t addr, struct psw psw); >>> void smp_teardown(void); >>> diff --git a/s390x/smp.c b/s390x/smp.c >>> index c7ff0ee..bad2131 100644 >>> --- a/s390x/smp.c >>> +++ b/s390x/smp.c >>> @@ -75,7 +75,12 @@ static void test_stop_store_status(void) >>> lc->prefix_sa = 0; >>> lc->grs_sa[15] = 0; >>> smp_cpu_stop_store_status(1); >>> - mb(); >>> + /* >>> + * This loop is workaround for KVM not reporting cc 2 for SIGP >>> + * sense if a stop and store status is pending. >>> + */ >>> + while (!lc->prefix_sa) >>> + mb(); >>> report(lc->prefix_sa == (uint32_t)(uintptr_t)cpu->lowcore, "prefix"); >>> report(lc->grs_sa[15], "stack"); >>> report(smp_cpu_stopped(1), "cpu stopped"); >>> @@ -85,7 +90,8 @@ static void test_stop_store_status(void) >>> lc->prefix_sa = 0; >>> lc->grs_sa[15] = 0; >>> smp_cpu_stop_store_status(1); >>> - mb(); >>> + while (!lc->prefix_sa) >>> + mb(); >>> report(lc->prefix_sa == (uint32_t)(uintptr_t)cpu->lowcore, "prefix"); >>> report(lc->grs_sa[15], "stack"); >>> report_prefix_pop(); >>> @@ -215,6 +221,7 @@ static void test_reset_initial(void) >>> wait_for_flag(); >>> >>> sigp_retry(1, SIGP_INITIAL_CPU_RESET, 0, NULL); >>> + smp_cpu_wait_for_completion(1); >> >> ^ is this really helpful? The next order already properly synchronizes, no? > > Well, the next order isn't issued with sigp_retry, so we could actually > get a cc 2 on the store. I need a cpu stopped loop here as well. ... should that one then simply have a retry? > >> >>> sigp(1, SIGP_STORE_STATUS_AT_ADDRESS, (uintptr_t)status, NULL); >>> >>> report_prefix_push("clear"); >>> @@ -265,6 +272,7 @@ static void test_reset(void) >>> smp_cpu_start(1, psw); >>> >>> sigp_retry(1, SIGP_CPU_RESET, 0, NULL); >>> + smp_cpu_wait_for_completion(1); >> >> Isn't this racy for KVM as well? >> >> I would have expected a loop until it is actually stopped. > > I'd add a loop with a comment, but also keep the wait for completion. I don't see how the wait for completion is really useful here. The wait for stop will do the very same then. -- Thanks, David / dhildenb