Re: [Qemu-devel] [PATCH 2/7] s390x/pci: rework PCI STORE

[Cornelia Huck <cohuck@redhat.com>]

On Tue,  7 Nov 2017 18:24:34 +0100
Pierre Morel <pmorel@linux.vnet.ibm.com> wrote:

> Enhance the fault detection, correction of the fault reporting.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
> Reviewed-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
> ---
>  hw/s390x/s390-pci-inst.c | 41 ++++++++++++++++++++++++-----------------
>  1 file changed, 24 insertions(+), 17 deletions(-)
> 
> diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
> index 8fcb02d..4a2f996 100644
> --- a/hw/s390x/s390-pci-inst.c
> +++ b/hw/s390x/s390-pci-inst.c
> @@ -469,6 +469,12 @@ int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2)
>      pcias = (env->regs[r2] >> 16) & 0xf;
>      len = env->regs[r2] & 0xf;
>      offset = env->regs[r2 + 1];
> +    data = env->regs[r1];
> +
> +    if (!(fh & FH_MASK_ENABLE)) {

This covers the reserved/standby/disabled states, right?

> +        setcc(cpu, ZPCI_PCI_LS_INVAL_HANDLE);
> +        return 0;
> +    }
>  
>      pbdev = s390_pci_find_dev_by_fh(s390_get_phb(), fh);
>      if (!pbdev) {
> @@ -478,12 +484,7 @@ int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2)
>      }
>  
>      switch (pbdev->state) {
> -    case ZPCI_FS_RESERVED:
> -    case ZPCI_FS_STANDBY:
> -    case ZPCI_FS_DISABLED:
>      case ZPCI_FS_PERMANENT_ERROR:
> -        setcc(cpu, ZPCI_PCI_LS_INVAL_HANDLE);
> -        return 0;
>      case ZPCI_FS_ERROR:
>          setcc(cpu, ZPCI_PCI_LS_ERR);
>          s390_set_status_code(env, r2, ZPCI_PCI_ST_BLOCKED);
> @@ -492,9 +493,13 @@ int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2)
>          break;
>      }
>  
> -    data = env->regs[r1];
> -    if (pcias < 6) {
> -        if ((8 - (offset & 0x7)) < len) {
> +    /* Test that the pcias is a valid pcias and do the according operations */

s/according/appropriate/ ?

> +    switch (pcias) {
> +    case 0 ... 5:
> +        /* Check length:
> +         * A length of 0 is invalid and length should not cross a double word
> +         */
> +        if (!len || (len > (8 - (offset & 0x7)))) {
>              program_interrupt(env, PGM_OPERAND, 4);
>              return 0;
>          }
> @@ -512,21 +517,23 @@ int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2)
>              program_interrupt(env, PGM_OPERAND, 4);
>              return 0;
>          }
> -    } else if (pcias == 15) {
> -        if ((4 - (offset & 0x3)) < len) {
> -            program_interrupt(env, PGM_OPERAND, 4);
> -            return 0;
> -        }
> -
> -        if (zpci_endian_swap(&data, len)) {
> +        break;
> +    case 15:
> +        /* ZPCI uses the pseudo BAR number 15 as configuration space */
> +        /* possible access length are 1,2,4 and must not cross a word */

s/length/lengths/

> +        if (!len || (len > (4 - (offset & 0x3))) || len == 3) {
>              program_interrupt(env, PGM_OPERAND, 4);
>              return 0;
>          }
> -
> +        /* len = 1,2,4 so we do not need to test */
> +        zpci_endian_swap(&data, len);
>          pci_host_config_write_common(pbdev->pdev, offset,
>                                       pci_config_size(pbdev->pdev),
>                                       data, len);
> -    } else {
> +        break;
> +    case PCI_ROM_SLOT:

So, will this be filled in a later patch? (Reading from the top.)

> +        /* Fall through */
> +    default:
>          DPRINTF("pcistg invalid space\n");
>          setcc(cpu, ZPCI_PCI_LS_ERR);
>          s390_set_status_code(env, r2, ZPCI_PCI_ST_INVAL_AS);

On the whole, I think this improves readability, especially for folks
that do not have access to the spec.