Re: [kvm-unit-tests PATCH v2 1/3] s390x: Fix initial cr0 load comments

Thomas Huth
2019-11-12T09:26:13Z

On 11/11/2019 16.33, Janosch Frank wrote:
> We need to load cr0 to have access to all fprs during save and restore
> of fprs. Saving conditionally on basis of the CR0 AFP bit would be a
> pain.
>
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
> s390x/cstart64.S | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/s390x/cstart64.S b/s390x/cstart64.S
> index 8e2b21e..043e34a 100644
> --- a/s390x/cstart64.S
> +++ b/s390x/cstart64.S
> @@ -94,7 +94,7 @@ memsetxc:
> stmg %r0, %r15, GEN_LC_SW_INT_GRS
> /* save cr0 */
> stctg %c0, %c0, GEN_LC_SW_INT_CR0
> - /* load initial cr0 again */
> + /* load a cr0 that has the AFP control bit which enables all FPRs */
> larl %r1, initial_cr0
> lctlg %c0, %c0, 0(%r1)
> /* save fprs 0-15 + fpc */
> @@ -139,7 +139,7 @@ diag308_load_reset:
> xgr %r2, %r2
> br %r14
> /* Success path */
> - /* We lost cr0 due to the reset */
> + /* load a cr0 that has the AFP control bit which enables all FPRs */
> 0: larl %r1, initial_cr0
> lctlg %c0, %c0, 0(%r1)
> RESTORE_REGS
>

Reviewed-by: Thomas Huth <thuth@redhat.com>