Re: [PATCH v12 07/35] s390x/diag: Implement DIAG 320 subcode 1

[Eric Farman <farman@linux.ibm.com>]

On Wed, 2026-07-01 at 16:48 -0400, 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>
> Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
> Reviewed-by: Collin Walling <walling@linux.ibm.com>
> ---
>  docs/specs/s390x-secure-ipl.rst | 12 ++++++
>  hw/s390x/cert-store.h           |  3 +-
>  include/hw/s390x/ipl/diag320.h  | 57 +++++++++++++++++++++++++++++
>  target/s390x/diag.c             | 65 ++++++++++++++++++++++++++++++++-
>  4 files changed, 134 insertions(+), 3 deletions(-)

One nit below; but either way...

Reviewed-by: Eric Farman <farman@linux.ibm.com>

> 
> diff --git a/docs/specs/s390x-secure-ipl.rst b/docs/specs/s390x-secure-ipl.rst
> index 331d793008..d5d4c3a24d 100644
> --- a/docs/specs/s390x-secure-ipl.rst
> +++ b/docs/specs/s390x-secure-ipl.rst
> @@ -30,3 +30,15 @@ Subcode 0 - query installed subcodes
>      Returns a 256-bit installed subcodes mask (ISM) stored in the installed
>      subcodes block (ISB). This mask indicates which subcodes 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/hw/s390x/cert-store.h b/hw/s390x/cert-store.h
> index 7fc9503cb9..6f5ee63177 100644
> --- a/hw/s390x/cert-store.h
> +++ b/hw/s390x/cert-store.h
> @@ -11,10 +11,9 @@
>  #define HW_S390_CERT_STORE_H
>  
>  #include "hw/s390x/ipl/qipl.h"
> +#include "hw/s390x/ipl/diag320.h"
>  #include "crypto/x509-utils.h"
>  
> -#define CERT_NAME_MAX_LEN  64
> -
>  #define CERT_KEY_ID_LEN    QCRYPTO_HASH_DIGEST_LEN_SHA256
>  #define CERT_HASH_LEN      QCRYPTO_HASH_DIGEST_LEN_SHA256
>  
> diff --git a/include/hw/s390x/ipl/diag320.h b/include/hw/s390x/ipl/diag320.h
> index aa04b699c6..d37d8eaa86 100644
> --- a/include/hw/s390x/ipl/diag320.h
> +++ b/include/hw/s390x/ipl/diag320.h
> @@ -11,10 +11,67 @@
>  #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_LEN_VALID   128
> +
> +#define CERT_NAME_MAX_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;
> +
> +struct VCEntryHeader {
> +    uint32_t len;
> +    uint8_t flags;
> +    uint8_t key_type;
> +    uint16_t cert_idx;
> +    uint8_t name[CERT_NAME_MAX_LEN];
> +    uint8_t format;
> +    uint8_t reserved0;
> +    uint16_t keyid_len;
> +    uint8_t reserved1;
> +    uint8_t hash_type;
> +    uint16_t hash_len;
> +    uint32_t reserved2;
> +    uint32_t cert_len;
> +    uint32_t reserved3[2];
> +    uint16_t hash_offset;
> +    uint16_t cert_offset;
> +    uint32_t reserved4[7];
> +};
> +typedef struct VCEntryHeader VCEntryHeader;
> +
> +struct VCBlockHeader {
> +    uint32_t in_len;
> +    uint32_t reserved0;
> +    uint16_t first_vc_index;
> +    uint16_t last_vc_index;
> +    uint32_t reserved1[5];
> +    uint32_t out_len;
> +    uint8_t reserved2[4];
> +    uint16_t stored_ct;
> +    uint16_t remain_ct;
> +    uint32_t reserved3[5];
> +};
> +typedef struct VCBlockHeader VCBlockHeader;
>  
>  #endif
> diff --git a/target/s390x/diag.c b/target/s390x/diag.c
> index 9f98e4b677..2336732c9f 100644
> --- a/target/s390x/diag.c
> +++ b/target/s390x/diag.c
> @@ -205,11 +205,56 @@ out:
>      }
>  }
>  
> +static int handle_diag320_query_vcsi(S390CPU *cpu, uint64_t addr, uint64_t r1,
> +                                     uintptr_t ra, S390IPLCertificateStore *cs)
> +{
> +    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) > sizeof(*vcssb)) {
> +        return DIAG_320_RC_INVAL_VCSSB_LEN;
> +    }
> +
> +    if (be32_to_cpu(vcssb->length) < VCSSB_LEN_VALID) {
> +        return DIAG_320_RC_INVAL_VCSSB_LEN;
> +    }

These two checks could be squashed together, because the QEMU_BUILD_BUG below ensures that
sizeof(*vcssb) == VCSSB_LEN_VALID, and so vcssb->length should also be only that.

> +
> +    if (!cs->count) {
> +        vcssb->length = cpu_to_be32(VCSSB_NO_VC);
> +    } else {
> +        vcssb->version = 0;
> +        vcssb->total_vc_ct = cpu_to_be16(cs->count);
> +        vcssb->max_vc_ct = cpu_to_be16(MAX_CERTIFICATES);
> +        vcssb->max_single_vcb_len = cpu_to_be32(sizeof(VCBlockHeader) +
> +                                                sizeof(VCEntryHeader) +
> +                                                cs->largest_cert_size);
> +        vcssb->total_vcb_len = cpu_to_be32(sizeof(VCBlockHeader) +
> +                                           cs->count * sizeof(VCEntryHeader) +
> +                                           cs->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_LEN_VALID,
> +                   "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 *cs = 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);
> @@ -231,7 +276,8 @@ 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);
> @@ -240,6 +286,23 @@ 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 (addr & 0x7) {
> +            s390_program_interrupt(env, PGM_SPECIFICATION, ra);
> +            return;
> +        }
> +
> +        if (!diag_parm_addr_valid(addr, sizeof(VCStorageSizeBlock), true)) {
> +            s390_program_interrupt(env, PGM_ADDRESSING, ra);
> +            return;
> +        }
> +
> +        rc = handle_diag320_query_vcsi(cpu, addr, r1, ra, cs);
> +        if (rc == -1) {
> +            return;
> +        }
> +        env->regs[r1 + 1] = rc;
> +        break;
>      default:
>          env->regs[r1 + 1] = DIAG_320_RC_NOT_SUPPORTED;
>          break;