From: Christian Borntraeger <borntraeger@de.ibm.com>
To: David Hildenbrand <david@redhat.com>, qemu-devel@nongnu.org
Cc: Thomas Huth <thuth@redhat.com>,
Janosch Frank <frankja@linux.ibm.com>,
"Michael S . Tsirkin" <mst@redhat.com>,
Heiko Carstens <hca@linux.ibm.com>,
Cornelia Huck <cohuck@redhat.com>,
Halil Pasic <pasic@linux.ibm.com>,
qemu-s390x@nongnu.org, Claudio Imbrenda <imbrenda@linux.ibm.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH RFC 2/5] s390x: implement diag260
Date: Thu, 9 Jul 2020 12:52:56 +0200 [thread overview]
Message-ID: <efe7e845-2e0f-96ba-7e29-c6ac74db9e2f@de.ibm.com> (raw)
In-Reply-To: <20200708185135.46694-3-david@redhat.com>
On 08.07.20 20:51, David Hildenbrand wrote:
> Let's implement the "storage configuration" part of diag260. This diag
> is found under z/VM, to indicate usable chunks of memory tot he guest OS.
> As I don't have access to documentation, I have no clue what the actual
> error cases are, and which other stuff we could eventually query using this
> interface. Somebody with access to documentation should fix this. This
> implementation seems to work with Linux guests just fine.
>
> The Linux kernel supports diag260 to query the available memory since
> v4.20. Older kernels / kvm-unit-tests will later fail to run in such a VM
> (with maxmem being defined and bigger than the memory size, e.g., "-m
> 2G,maxmem=4G"), just as if support for SCLP storage information is not
> implemented. They will fail to detect the actual initial memory size.
>
> This interface allows us to expose the maximum ramsize via sclp
> and the initial ramsize via diag260 - without having to mess with the
> memory increment size and having to align the initial memory size to it.
>
> This is a preparation for memory device support. We'll unlock the
> implementation with a new QEMU machine that supports memory devices.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
I have not looked into this, so this is purely a question.
Is there a way to hotplug virtio-mem memory beyond the initial size of
the memory as specified by the initial sclp)? then we could avoid doing
this platform specfic diag260?
the only issue I see is when we need to go beyond 4TB due to the page table
upgrade in the kernel.
FWIW diag 260 is publicly documented.
next prev parent reply other threads:[~2020-07-09 10:53 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-08 18:51 [PATCH RFC 0/5] s390x: initial support for virtio-mem David Hildenbrand
2020-07-08 18:51 ` [PATCH RFC 1/5] s390x: move setting of maximum ram size to machine init David Hildenbrand
2020-07-08 18:51 ` [PATCH RFC 2/5] s390x: implement diag260 David Hildenbrand
2020-07-09 10:37 ` Cornelia Huck
2020-07-09 17:54 ` David Hildenbrand
2020-07-10 8:32 ` David Hildenbrand
2020-07-10 8:41 ` David Hildenbrand
2020-07-10 9:19 ` Cornelia Huck
2020-07-13 11:54 ` Christian Borntraeger
2020-07-13 12:11 ` Cornelia Huck
2020-07-13 12:13 ` Christian Borntraeger
2020-07-09 10:52 ` Christian Borntraeger [this message]
2020-07-09 18:15 ` David Hildenbrand
2020-07-10 9:17 ` David Hildenbrand
2020-07-10 12:12 ` David Hildenbrand
2020-07-10 15:18 ` Heiko Carstens
2020-07-10 15:24 ` David Hildenbrand
2020-07-10 15:43 ` Heiko Carstens
2020-07-10 15:45 ` David Hildenbrand
2020-07-13 9:12 ` Heiko Carstens
2020-07-13 10:27 ` David Hildenbrand
2020-07-13 11:08 ` Christian Borntraeger
2020-07-15 9:42 ` David Hildenbrand
2020-07-15 10:43 ` Heiko Carstens
2020-07-15 11:21 ` David Hildenbrand
2020-07-15 11:34 ` Heiko Carstens
2020-07-15 11:42 ` David Hildenbrand
2020-07-15 16:14 ` Heiko Carstens
2020-07-15 17:38 ` David Hildenbrand
2020-07-15 17:51 ` David Hildenbrand
2020-07-20 14:43 ` Heiko Carstens
2020-07-20 15:43 ` David Hildenbrand
2020-07-08 18:51 ` [PATCH RFC 3/5] s390x: prepare device memory address space David Hildenbrand
2020-07-09 10:59 ` Cornelia Huck
2020-07-10 7:46 ` David Hildenbrand
2020-07-08 18:51 ` [PATCH RFC 4/5] s390x: implement virtio-mem-ccw David Hildenbrand
2020-07-09 9:24 ` Cornelia Huck
2020-07-09 9:26 ` David Hildenbrand
2020-07-08 18:51 ` [PATCH RFC 5/5] s390x: initial support for virtio-mem David Hildenbrand
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