Re: [PATCH v6 07/28] s390x/diag: Implement DIAG 320 subcode 1

[Farhan Ali <alifm@linux.ibm.com>]

Reviewed-by: Farhan Ali <alifm@linux.ibm.com>

On 9/17/2025 4:21 PM, Zhuoying Cai wrote:
> DIAG 320 subcode 1 provides information needed to determine
> the amount of storage to store one or more certificates from the
> certificate store.
>
> Upon successful completion, this subcode returns information of the current
> cert store, such as the number of certificates stored and allowed in the cert
> store, amount of space may need to be allocate to store a certificate,
> etc for verification-certificate blocks (VCBs).
>
> The subcode value is denoted by setting the left-most bit
> of an 8-byte field.
>
> The verification-certificate-storage-size block (VCSSB) contains
> the output data when the operation completes successfully. A VCSSB
> length of 4 indicates that no certificate are available in the cert
> store.
>
> Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
> ---
>   docs/specs/s390x-secure-ipl.rst | 10 ++++++
>   include/hw/s390x/ipl/diag320.h  | 22 ++++++++++++
>   target/s390x/diag.c             | 59 ++++++++++++++++++++++++++++++++-
>   3 files changed, 90 insertions(+), 1 deletion(-)
>
> diff --git a/docs/specs/s390x-secure-ipl.rst b/docs/specs/s390x-secure-ipl.rst
> index 30ddc81c2b..4217f19c84 100644
> --- a/docs/specs/s390x-secure-ipl.rst
> +++ b/docs/specs/s390x-secure-ipl.rst
> @@ -25,3 +25,13 @@ Subcode 0 - query installed subcodes
>       Returns a 256-bit installed subcodes mask (ISM) stored in the installed
>       subcodes block (ISB). This mask indicates which sucodes are currently
>       installed and available for use.
> +
> +Subcode 1 - query verification certificate storage information
> +    Provides the information required to determine the amount of memory needed to
> +    store one or more verification-certificates (VCs) from the certificate store (CS).
> +
> +    Upon successful completion, this subcode returns various storage size values for
> +    verification-certificate blocks (VCBs).
> +
> +    The output is returned in the verification-certificate-storage-size block (VCSSB).
> +    A VCSSB length of 4 indicates that no certificates are available in the CS.
> diff --git a/include/hw/s390x/ipl/diag320.h b/include/hw/s390x/ipl/diag320.h
> index aa04b699c6..6e4779c699 100644
> --- a/include/hw/s390x/ipl/diag320.h
> +++ b/include/hw/s390x/ipl/diag320.h
> @@ -11,10 +11,32 @@
>   #define S390X_DIAG320_H
>   
>   #define DIAG_320_SUBC_QUERY_ISM     0
> +#define DIAG_320_SUBC_QUERY_VCSI    1
>   
>   #define DIAG_320_RC_OK              0x0001
>   #define DIAG_320_RC_NOT_SUPPORTED   0x0102
> +#define DIAG_320_RC_INVAL_VCSSB_LEN 0x0202
>   
>   #define DIAG_320_ISM_QUERY_SUBCODES 0x80000000
> +#define DIAG_320_ISM_QUERY_VCSI     0x40000000
> +
> +#define VCSSB_NO_VC     4
> +#define VCSSB_MIN_LEN   128
> +#define VCE_HEADER_LEN  128
> +#define VCB_HEADER_LEN  64
> +
> +struct VCStorageSizeBlock {
> +    uint32_t length;
> +    uint8_t reserved0[3];
> +    uint8_t version;
> +    uint32_t reserved1[6];
> +    uint16_t total_vc_ct;
> +    uint16_t max_vc_ct;
> +    uint32_t reserved3[11];
> +    uint32_t max_single_vcb_len;
> +    uint32_t total_vcb_len;
> +    uint32_t reserved4[10];
> +};
> +typedef struct VCStorageSizeBlock VCStorageSizeBlock;
>   
>   #endif
> diff --git a/target/s390x/diag.c b/target/s390x/diag.c
> index e67ee57f01..4e6de483b8 100644
> --- a/target/s390x/diag.c
> +++ b/target/s390x/diag.c
> @@ -191,11 +191,50 @@ out:
>       }
>   }
>   
> +static int handle_diag320_query_vcsi(S390CPU *cpu, uint64_t addr, uint64_t r1,
> +                                     uintptr_t ra, S390IPLCertificateStore *qcs)
> +{
> +    g_autofree VCStorageSizeBlock *vcssb = NULL;
> +
> +    vcssb = g_new0(VCStorageSizeBlock, 1);
> +    if (s390_cpu_virt_mem_read(cpu, addr, r1, vcssb, sizeof(*vcssb))) {
> +        s390_cpu_virt_mem_handle_exc(cpu, ra);
> +        return -1;
> +    }
> +
> +    if (be32_to_cpu(vcssb->length) < VCSSB_MIN_LEN) {
> +        return DIAG_320_RC_INVAL_VCSSB_LEN;
> +    }
> +
> +    if (!qcs->count) {
> +        vcssb->length = cpu_to_be32(VCSSB_NO_VC);
> +    } else {
> +        vcssb->version = 0;
> +        vcssb->total_vc_ct = cpu_to_be16(qcs->count);
> +        vcssb->max_vc_ct = cpu_to_be16(MAX_CERTIFICATES);
> +        vcssb->max_single_vcb_len = cpu_to_be32(VCB_HEADER_LEN + VCE_HEADER_LEN +
> +                                                qcs->max_cert_size);
> +        vcssb->total_vcb_len = cpu_to_be32(VCB_HEADER_LEN + qcs->count * VCE_HEADER_LEN +
> +                                           qcs->total_bytes);
> +    }
> +
> +    if (s390_cpu_virt_mem_write(cpu, addr, r1, vcssb, be32_to_cpu(vcssb->length))) {
> +        s390_cpu_virt_mem_handle_exc(cpu, ra);
> +        return -1;
> +    }
> +    return DIAG_320_RC_OK;
> +}
> +
> +QEMU_BUILD_BUG_MSG(sizeof(VCStorageSizeBlock) != VCSSB_MIN_LEN,
> +                   "size of VCStorageSizeBlock is wrong");
> +
>   void handle_diag_320(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
>   {
>       S390CPU *cpu = env_archcpu(env);
> +    S390IPLCertificateStore *qcs = s390_ipl_get_certificate_store();
>       uint64_t subcode = env->regs[r3];
>       uint64_t addr = env->regs[r1];
> +    int rc;
>   
>       if (env->psw.mask & PSW_MASK_PSTATE) {
>           s390_program_interrupt(env, PGM_PRIVILEGED, ra);
> @@ -219,7 +258,8 @@ void handle_diag_320(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
>            * but the current set of subcodes can fit within a single word
>            * for now.
>            */
> -        uint32_t ism_word0 = cpu_to_be32(DIAG_320_ISM_QUERY_SUBCODES);
> +        uint32_t ism_word0 = cpu_to_be32(DIAG_320_ISM_QUERY_SUBCODES |
> +                                         DIAG_320_ISM_QUERY_VCSI);
>   
>           if (s390_cpu_virt_mem_write(cpu, addr, r1, &ism_word0, sizeof(ism_word0))) {
>               s390_cpu_virt_mem_handle_exc(cpu, ra);
> @@ -228,6 +268,23 @@ void handle_diag_320(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
>   
>           env->regs[r1 + 1] = DIAG_320_RC_OK;
>           break;
> +    case DIAG_320_SUBC_QUERY_VCSI:
> +        if (!diag_parm_addr_valid(addr, sizeof(VCStorageSizeBlock), true)) {
> +            s390_program_interrupt(env, PGM_ADDRESSING, ra);
> +            return;
> +        }
> +
> +        if (addr & 0x7) {
> +            s390_program_interrupt(env, PGM_ADDRESSING, ra);
> +            return;
> +        }
> +
> +        rc = handle_diag320_query_vcsi(cpu, addr, r1, ra, qcs);
> +        if (rc == -1) {
> +            return;
> +        }
> +        env->regs[r1 + 1] = rc;
> +        break;
>       default:
>           env->regs[r1 + 1] = DIAG_320_RC_NOT_SUPPORTED;
>           break;