Re: [kvm-unit-tests PATCH v2 2/3] s390x: uv-host: Explain why we set up the home space and remove the space change

[Thomas Huth <thuth@redhat.com>]

On 20/08/2021 13.39, Janosch Frank wrote:
> UV home addresses don't require us to be in home space but we need to
> have it set up so hw/fw can use the home asce to translate home
> virtual addresses.
> 
> Hence we add a comment why we're setting up the home asce and remove
> the address space since it's unneeded.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>   s390x/uv-host.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/s390x/uv-host.c b/s390x/uv-host.c
> index 426a67f6..28035707 100644
> --- a/s390x/uv-host.c
> +++ b/s390x/uv-host.c
> @@ -444,13 +444,18 @@ static void test_clear(void)
>   
>   static void setup_vmem(void)
>   {
> -	uint64_t asce, mask;
> +	uint64_t asce;
>   
>   	setup_mmu(get_max_ram_size(), NULL);
> +	/*
> +	 * setup_mmu() will enable DAT and set the primary address
> +	 * space but we need to have a valid home space since UV calls
> +	 * take home space virtual addresses.
> +	 *
> +	 * Hence we just copy the primary asce into the home space.
> +	 */
>   	asce = stctg(1);
>   	lctlg(13, asce);
> -	mask = extract_psw_mask() | 0x0000C00000000000UL;
> -	load_psw_mask(mask);
>   }
>   
>   int main(void)
> 

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