On Wed, 5 Feb 2020 13:21:26 -0500
"Jason J. Herne" <jjhe...@linux.ibm.com> wrote:
> This fixes vfio-ccw when booting non-Linux operating systems. Without this
> struct being packed, a few extra bytes of low core memory get overwritten when
> we assign a value to memory address 0 in jump_to_IPL_2. This is enough to
> cause some non-Linux OSes of fail when booting.
s/of/to/
>
> The problem was introduced by:
> 5c6f0d5f46a77d77 "pc-bios/s390x: Fix reset psw mask".
So, what introduced the problem was turning two 32 bit values into a 64
bit value?
>
> The fix is to pack the struct thereby removing the 4 bytes of padding that get
> added at the end, likely to allow an array of these structs to naturally align
> on an 8-byte boundary.
>
> Fixes: 5c6f0d5f46a7 ("pc-bios/s390x: Fix reset psw mask")
> CC: Janosch Frank <fran...@linux.ibm.com>
> Signed-off-by: Jason J. Herne <jjhe...@linux.ibm.com>
> ---
> pc-bios/s390-ccw/jump2ipl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
> index da13c43cc0..1e9eaa037f 100644
> --- a/pc-bios/s390-ccw/jump2ipl.c
> +++ b/pc-bios/s390-ccw/jump2ipl.c
> @@ -18,7 +18,7 @@
> typedef struct ResetInfo {
> uint64_t ipl_psw;
> uint32_t ipl_continue;
> -} ResetInfo;
> +} __attribute__((packed)) ResetInfo;
>
> static ResetInfo save;
>
I'm wondering if we have more stuff like that lurking in the bios.
