Linux kernel 5.1 added a new PPC KVM capability named
KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST, which is exposed to the QEMU guest
since QEMU commit 8ff43ee404d under a new sPAPR capability called
SPAPR_CAP_CCF_ASSIST. This cap indicates whether the processor supports
hardware acceleration for the count cache flush workaround, which
is a software workaround that flushes the count cache on context
switch. If the processor has this hardware acceleration, the software
flush can be shortened, resulting in performance gain.
This hardware acceleration is defaulted to 'off' in QEMU. The reason
is that earlier versions of the Power 9 processor didn't support
it (it is available on Power 9 DD2.3 and newer), and defaulting this
option to 'on' would break migration compatibility between the Power 9
processor class.
However, the user running a P9 DD2.3+ hypervisor might want to create
guests with ccf-assist=on, accepting the downside of only being able
to migrate them only between other P9 DD2.3+ hosts running upstream
kernel 5.1+, to get a performance boost.
This patch adds this new capability to Libvirt, with the name of
QEMU_CAPS_MACHINE_PSERIES_CAP_CCF_ASSIST.
Reviewed-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
QEMU 2.11 for ppc64 changed all CPU model names to lower case. Since
libvirt can't change the model names for compatibility reasons, we need
to translate the matching lower case models to the names known by
libvirt.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
This reverts commit 0cebb6422a.
This capability is not used anywhere and also it is not contained
in any release so it's safe to just remove it.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Datagram socket is available since qemu 4.0, commit
fdec16e3c2a614e2861f3086b05d444b5d8c3406 ("net/socket: learn to talk
with a unix dgram socket").
Required for slirp-helper communication.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
QEMU 4.0.0 and newer automatically drops caches at the end of migration.
Let's check for this capability so that we can allow migration when disk
cache is turned on.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Acked-By: Peter Krempa <pkrempa@redhat.com>
Check whether qemu supports the bochs-display device and set a
capability. Update tests.
Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Add two capabilities for testing features required for the upcoming
virDomainBackupBegin: use block-dirty-bitmap-merge as the generic
witness of bitmap support needed for checkpoints (since all of the
bitmap management functionalities were finalized in the same qemu 4.0
release), and the bitmap parameter to nbd-server-add for pull-mode
backup support. Even though both capabilities are likely to be
present or absent together (that is, it is unlikely to encounter a
qemu that backports only one of the two), it still makes sense to keep
two capabilities as the two uses are orthogonal (full backups don't
require checkpoints, push mode backups don't require NBD bitmap
support, and checkpoints can be used for more than just incremental
backups).
Existing code is not affected by the new capabilities.
Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: Peter Krempa <pkrempa@redhat.com>
