Re: [kvm-unit-tests PATCH v4 3/9] s390x: SCLP feature checking

Claudio Imbrenda
2021-01-14T14:46:29Z

On Tue, 12 Jan 2021 08:20:48 -0500
Janosch Frank <frankja@linux.ibm.com> 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 <frankja@linux.ibm.com>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> ---
> lib/s390x/io.c | 1 +
> lib/s390x/sclp.c | 25 +++++++++++++++++++++++++
> lib/s390x/sclp.h | 13 ++++++++++++-
> 3 files changed, 38 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 12916f5..06819a6 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -25,6 +25,7 @@ static uint64_t max_ram_size;
> static uint64_t ram_size;
> char _read_info[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
> static ReadInfo *read_info;
> +struct sclp_facilities sclp_facilities;
>
> char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096)));
> static volatile bool sclp_busy;
> @@ -128,6 +129,30 @@ CPUEntry *sclp_get_cpu_entries(void)
> return (CPUEntry *)(_read_info + read_info->offset_cpu);
> }
>
> +void sclp_facilities_setup(void)
> +{
> + unsigned short cpu0_addr = stap();
> + CPUEntry *cpu;
> + int i;
> +
> + assert(read_info);
> +
> + cpu = sclp_get_cpu_entries();
> + for (i = 0; i < read_info->entries_cpu; i++, cpu++) {
> + /*
> + * The logic for only reading the facilities from the
> + * boot cpu comes from the kernel. I haven't yet
> found
> + * documentation that explains why this is necessary
> + * but I figure there's a reason behind doing it this
> + * way.
> + */
> + if (cpu->address == cpu0_addr) {
> + sclp_facilities.has_sief2 = cpu->feat_sief2;
> + break;
> + }
> + }
> +}
> +
> /* 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);

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>