Re: [PATCH RFC 3/5] s390x: prepare device memory address space

From: Cornelia Huck <cohuck@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: Thomas Huth <thuth@redhat.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	qemu-devel@nongnu.org, Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	qemu-s390x@nongnu.org, Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH RFC 3/5] s390x: prepare device memory address space
Date: Thu, 9 Jul 2020 12:59:49 +0200	[thread overview]
Message-ID: <20200709125949.7870d454.cohuck@redhat.com> (raw)
In-Reply-To: <20200708185135.46694-4-david@redhat.com>

On Wed,  8 Jul 2020 20:51:33 +0200
David Hildenbrand <david@redhat.com> wrote:

> Let's allocate the device memory information and setup the device
> memory address space. Expose the maximum ramsize via SCLP and the actual
> initial ramsize via diag260.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/s390x/s390-virtio-ccw.c         | 43 ++++++++++++++++++++++++++++++
>  hw/s390x/sclp.c                    | 12 +++++++--
>  include/hw/s390x/s390-virtio-ccw.h |  3 +++
>  target/s390x/diag.c                |  4 +--
>  4 files changed, 58 insertions(+), 4 deletions(-)

(...)

> diff --git a/target/s390x/diag.c b/target/s390x/diag.c
> index c3b1e24b2c..6b33eb0efc 100644
> --- a/target/s390x/diag.c
> +++ b/target/s390x/diag.c
> @@ -32,8 +32,8 @@ void handle_diag_260(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
>      ram_addr_t addr, length;
>      uint64_t tmp;
>  
> -    /* TODO: Unlock with new QEMU machine. */
> -    if (false) {
> +    /* Support for diag260 is glued to support for memory devices. */

I'm wondering why you need to do this... sure, the availability of a
new diagnose could be perceived as a guest-visible change, but does the
information presented change anything? Without memory devices, it will
just duplicate the information already reported via SCLP, IIUC?

> +    if (!memory_devices_allowed()) {
>          s390_program_interrupt(env, PGM_OPERATION, ra);
>          return;
>      }