Re: [PATCH v16 03/11] target/s390x/cpu topology: handle STSI(15) and build the SYSIB

[Thomas Huth]

On 22/02/2023 15.20, Pierre Morel wrote:
> On interception of STSI(15.1.x) the System Information Block
> (SYSIB) is built from the list of pre-ordered topology entries.
>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
...
> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> index d654267a71..c899f4e04b 100644
> --- a/target/s390x/cpu.h
> +++ b/target/s390x/cpu.h
> @@ -560,6 +560,25 @@ typedef struct SysIB_322 {
>   } SysIB_322;
>   QEMU_BUILD_BUG_ON(sizeof(SysIB_322) != 4096);
>   
> +#define S390_TOPOLOGY_MAG  6
> +#define S390_TOPOLOGY_MAG6 0
> +#define S390_TOPOLOGY_MAG5 1
> +#define S390_TOPOLOGY_MAG4 2
> +#define S390_TOPOLOGY_MAG3 3
> +#define S390_TOPOLOGY_MAG2 4
> +#define S390_TOPOLOGY_MAG1 5
> +/* Configuration topology */
> +typedef struct SysIB_151x {
> +    uint8_t  reserved0[2];
> +    uint16_t length;
> +    uint8_t  mag[S390_TOPOLOGY_MAG];
> +    uint8_t  reserved1;
> +    uint8_t  mnest;
> +    uint32_t reserved2;
> +    char tle[];
> +} QEMU_PACKED QEMU_ALIGNED(8) SysIB_151x;
> +QEMU_BUILD_BUG_ON(sizeof(SysIB_151x) != 16);

I think one of the two is enough, either QEMU_PACKED or QEMU_BUILD_BUG_ON. 
Since QEMU_PACKED caused us some troubles in the past already, I'd prefer 
QEMU_BUILD_BUG_ON only here.

Also, do we really need the QEMU_ALIGNED() here? ... I don't think so, and 
we also hardly use that anywhere else in the s390x code, so please drop 
that, too (unless there is a real reason for this?).

> @@ -567,9 +586,62 @@ typedef union SysIB {
>       SysIB_221 sysib_221;
>       SysIB_222 sysib_222;
>       SysIB_322 sysib_322;
> +    SysIB_151x sysib_151x;
>   } SysIB;
>   QEMU_BUILD_BUG_ON(sizeof(SysIB) != 4096);
>   
> +/*
> + * CPU Topology List provided by STSI with fc=15 provides a list
> + * of two different Topology List Entries (TLE) types to specify
> + * the topology hierarchy.
> + *
> + * - Container Topology List Entry
> + *   Defines a container to contain other Topology List Entries
> + *   of any type, nested containers or CPU.
> + * - CPU Topology List Entry
> + *   Specifies the CPUs position, type, entitlement and polarization
> + *   of the CPUs contained in the last Container TLE.
> + *
> + * There can be theoretically up to five levels of containers, QEMU
> + * uses only three levels, the drawer's, book's and socket's level.
> + *
> + * A container of with a nesting level (NL) greater than 1 can only
> + * contain another container of nesting level NL-1.
> + *
> + * A container of nesting level 1 (socket), contains as many CPU TLE
> + * as needed to describe the position and qualities of all CPUs inside
> + * the container.
> + * The qualities of a CPU are polarization, entitlement and type.
> + *
> + * The CPU TLE defines the position of the CPUs of identical qualities
> + * using a 64bits mask which first bit has its offset defined by
> + * the CPU address orgin field of the CPU TLE like in:
> + * CPU address = origin * 64 + bit position within the mask
> + *
> + */
> +/* Container type Topology List Entry */
> +typedef struct SysIBTl_container {
> +        uint8_t nl;
> +        uint8_t reserved[6];
> +        uint8_t id;
> +} QEMU_PACKED QEMU_ALIGNED(8) SysIBTl_container;

dito, please drop QEMU_PACKED and QEMU_ALIGNED() if possible.

> +QEMU_BUILD_BUG_ON(sizeof(SysIBTl_container) != 8);
> +
> +/* CPU type Topology List Entry */
> +typedef struct SysIBTl_cpu {
> +        uint8_t nl;
> +        uint8_t reserved0[3];
> +#define SYSIB_TLE_POLARITY_MASK 0x03
> +#define SYSIB_TLE_DEDICATED     0x04
> +        uint8_t flags;
> +        uint8_t type;
> +        uint16_t origin;
> +        uint64_t mask;
> +} QEMU_PACKED QEMU_ALIGNED(8) SysIBTl_cpu;

dito

 Thomas