Re: [PATCH v2 2/8] hw/s390x/ipl: Fix incorrect PCI IPL block length constant

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

On 8/24/26 1:53 PM, Zhuoying Cai wrote:
> On 8/11/26 10:46 AM, jrossi@linux.ibm.com wrote:
>> From: Jared Rossi <jrossi@linux.ibm.com>
>>
>> The IplBlockPci struct is 336 bytes in length.
>>
> 
> The commit message is slightly misleading because IplBlockPci itself is
> 312 bytes in length.
> 
> Maybe reword it to something like:
> "IplBlockPci is 312 bytes, so the minimum PCI IPLB length is 336 bytes."
> 

Given that, should the #define be sizeof(IplBlockPci) + 24?

And does the patch itself need to be cc'd to stable?

> Otherwise:
> Reviewed-by: Zhuoying Cai <zycai@linux.ibm.com>
> 
>> Fix the S390_IPLB_MIN_PCI_LEN to reflect this, and assign a valid blk0_len
>> while we are at it.
>>
>> Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
>> ---
>>   hw/s390x/ipl.c | 2 ++
>>   hw/s390x/ipl.h | 2 +-
>>   2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
>> index d5fdc3ea0f..fd6e9100f9 100644
>> --- a/hw/s390x/ipl.c
>> +++ b/hw/s390x/ipl.c
>> @@ -526,6 +526,8 @@ static bool s390_build_iplb(DeviceState *dev_st, IplParameterBlock *iplb)
>>           switch (devtype) {
>>           case PCI_DEVTYPE_VIRTIO:
>>               iplb->len = cpu_to_be32(S390_IPLB_MIN_PCI_LEN);
>> +            iplb->blk0_len =
>> +                cpu_to_be32(S390_IPLB_MIN_PCI_LEN - S390_IPLB_HEADER_LEN);
>>               iplb->pbt = S390_IPL_TYPE_PCI;
>>               iplb->pci.fid = cpu_to_be32(pbdev->fid);
>>               break;
>> diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
>> index fac30763df..b4d93054a7 100644
>> --- a/hw/s390x/ipl.h
>> +++ b/hw/s390x/ipl.h
>> @@ -107,7 +107,7 @@ QEMU_BUILD_BUG_MSG(offsetof(S390IPLState, iplb) & 3, "alignment of iplb wrong");
>>   #define S390_IPLB_MIN_PV_LEN 148
>>   #define S390_IPLB_MIN_CCW_LEN 200
>>   #define S390_IPLB_MIN_FCP_LEN 384
>> -#define S390_IPLB_MIN_PCI_LEN 376
>> +#define S390_IPLB_MIN_PCI_LEN 336
>>   #define S390_IPLB_MIN_QEMU_SCSI_LEN 200
>>   
>>   static inline bool iplb_valid_len(IplParameterBlock *iplb)
>