Re: [PATCH qemu] pc-bios/s390-ccw: Fix off-by-one errors with loadparm and boot entries

On 7/28/26 6:30 PM, [email protected] wrote:
> From: Jared Rossi <[email protected]>
> 
> The loadparm may optionally be used to select a boot entry, with the
> intended range being 0 through 31 inclusive, for a total of 32 entries.
> Previously, MAX_BOOT_ENTRIES was defined as 31, indicating that it was
> intended to correspond to the index of the boot entry rather than the
> count; however, some guards also used MAX_BOOT_ENTRIES as a count of the
> maximum allowed entries, which resulted in a mismatch between the intended
> and actual range such that index 31 could never be used in practice.
> 
> Move the definition of MAX_BOOT_ENTRIES to qipl.h so it is shared and
> change the value to 32, representing a count of the maximum number of
> allowed boot entries and allowing the loadparm to accept values 0 through
> 31 as intended.  Update some instances in the netboot code where
> MAX_BOOT_ENTRIES was used as the max index so that all guards treat
> MAX_BOOT_ENTRIES as a count across all boot methods.
> 
> Cc: [email protected]
> Fixes: 806315279d5c ("pc-bios/s390-ccw: Remove panics from ECKD IPL path")
> Signed-off-by: Jared Rossi <[email protected]>

Reviewed-by: Matthew Rosato <[email protected]>