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Thu, 17 Dec 2020 15:21:10 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E87CA42047; Thu, 17 Dec 2020 15:21:09 +0000 (GMT) Received: from localhost.localdomain (unknown [9.145.181.71]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 17 Dec 2020 15:21:09 +0000 (GMT) Subject: Re: [kvm-unit-tests PATCH v3 3/8] s390x: SCLP feature checking To: Claudio Imbrenda Cc: kvm@vger.kernel.org, thuth@redhat.com, david@redhat.com, borntraeger@de.ibm.com, cohuck@redhat.com, linux-s390@vger.kernel.org References: <20201211100039.63597-1-frankja@linux.ibm.com> <20201211100039.63597-4-frankja@linux.ibm.com> <20201217131837.5946c853@ibm-vm> From: Janosch Frank Message-ID: <14a2d6ab-7f9b-86cd-26ca-0c83385f62ca@linux.ibm.com> Date: Thu, 17 Dec 2020 16:21:09 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20201217131837.5946c853@ibm-vm> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.343,18.0.737 definitions=2020-12-17_09:2020-12-15,2020-12-17 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 mlxlogscore=999 suspectscore=0 adultscore=0 impostorscore=0 mlxscore=0 malwarescore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 clxscore=1015 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2012170103 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 12/17/20 1:18 PM, Claudio Imbrenda wrote: > On Fri, 11 Dec 2020 05:00:34 -0500 > Janosch Frank wrote: > >> Availability of SIE is announced via a feature bit in a SCLP info CPU >> entry. Let's add a framework that allows us to easily check for such >> facilities. >> >> Signed-off-by: Janosch Frank >> Reviewed-by: Thomas Huth >> --- >> lib/s390x/io.c | 1 + >> lib/s390x/sclp.c | 19 +++++++++++++++++++ >> lib/s390x/sclp.h | 13 ++++++++++++- >> 3 files changed, 32 insertions(+), 1 deletion(-) >> >> diff --git a/lib/s390x/io.c b/lib/s390x/io.c >> index 6a1da63..ef9f59e 100644 >> --- a/lib/s390x/io.c >> +++ b/lib/s390x/io.c >> @@ -35,6 +35,7 @@ void setup(void) >> setup_args_progname(ipl_args); >> setup_facilities(); >> sclp_read_info(); >> + sclp_facilities_setup(); >> sclp_console_setup(); >> sclp_memory_setup(); >> smp_setup(); >> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c >> index bf1d9c0..cf6ea7c 100644 >> --- a/lib/s390x/sclp.c >> +++ b/lib/s390x/sclp.c >> @@ -9,6 +9,7 @@ >> */ >> >> #include >> +#include > > you add this include, but it seems you are not actually using it? Leftover from last version > >> #include >> #include >> #include >> @@ -25,6 +26,7 @@ static uint64_t max_ram_size; >> static uint64_t ram_size; >> char _read_info[PAGE_SIZE] __attribute__((__aligned__(4096))); >> static ReadInfo *read_info; >> +struct sclp_facilities sclp_facilities; >> >> char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096))); >> static volatile bool sclp_busy; >> @@ -128,6 +130,23 @@ CPUEntry *sclp_get_cpu_entries(void) >> return (void *)read_info + read_info->offset_cpu; >> } >> >> +void sclp_facilities_setup(void) >> +{ >> + unsigned short cpu0_addr = stap(); >> + CPUEntry *cpu; >> + int i; >> + >> + assert(read_info); >> + >> + cpu = (void *)read_info + read_info->offset_cpu; > > another void* arithmetic. consider using well-defined constructs, like > > cpu = (CPUEntry *)(_read_info + read_info->offset_cpu); > >> + for (i = 0; i < read_info->entries_cpu; i++, cpu++) { >> + if (cpu->address == cpu0_addr) { >> + sclp_facilities.has_sief2 = cpu->feat_sief2; >> + break; > > this only checks CPU 0. I wonder if you shouldn't check all CPUs? Or if > we assume that all CPUs have the same facilities, isn't it enough to > check the first CPU in the list? (i.e. avoid the loop) This is the way. Thomas already asked me that. I had a look what the kernel does and that's what they are doing. QEMU writes the same feature bits to all cpus and I haven't found an explanation for that code yet but I figured there might (have) be(en) one. > >> + } >> + } >> +} >> + >> /* Perform service call. Return 0 on success, non-zero otherwise. */ >> int sclp_service_call(unsigned int command, void *sccb) >> { >> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h >> index acd86d5..6c86037 100644 >> --- a/lib/s390x/sclp.h >> +++ b/lib/s390x/sclp.h >> @@ -92,12 +92,22 @@ typedef struct SCCBHeader { >> typedef struct CPUEntry { >> uint8_t address; >> uint8_t reserved0; >> - uint8_t features[SCCB_CPU_FEATURE_LEN]; >> + uint8_t : 4; >> + uint8_t feat_sief2 : 1; >> + uint8_t : 3; >> + uint8_t features_res2 [SCCB_CPU_FEATURE_LEN - 1]; >> uint8_t reserved2[6]; >> uint8_t type; >> uint8_t reserved1; >> } __attribute__((packed)) CPUEntry; >> >> +extern struct sclp_facilities sclp_facilities; >> + >> +struct sclp_facilities { >> + uint64_t has_sief2 : 1; >> + uint64_t : 63; >> +}; >> + >> typedef struct ReadInfo { >> SCCBHeader h; >> uint16_t rnmax; >> @@ -271,6 +281,7 @@ void sclp_print(const char *str); >> void sclp_read_info(void); >> int sclp_get_cpu_num(void); >> CPUEntry *sclp_get_cpu_entries(void); >> +void sclp_facilities_setup(void); >> int sclp_service_call(unsigned int command, void *sccb); >> void sclp_memory_setup(void); >> uint64_t get_ram_size(void); >