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Paul Durrant
26fba3c855
This patch introduces an implementation of the STIMER0-15_CONFIG/COUNT MSRs
and hence a the first SynIC message source.
The new (and documented) 'stimer' viridian enlightenment group may be
specified to enable this feature.
While in the neighbourhood, this patch adds a missing check for an
attempt to write the time reference count MSR, which should result in an
exception (but not be reported as an unimplemented MSR).
NOTE: It is necessary for correct operation that timer expiration and
message delivery time-stamping use the same time source as the guest.
The specification is ambiguous but testing with a Windows 10 1803
guest has shown that using the partition reference counter as a
source whilst the guest is using RDTSC and the reference tsc page
does not work correctly. Therefore the time_now() function is used.
This implements the algorithm for acquiring partition reference time
that is documented in the specifiction.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Remus provides fault tolerance for virtual machines by sending continuous checkpoints to a backup, which will activate if the target VM fails. See the website at http://wiki.xen.org/wiki/Remus for details. Using Remus with libxl on Xen 4.5 and higher: To enable network buffering, you need libnl 3.2.8 or higher along with the development headers and command line utilities. If your distro does not have the appropriate libnl3 version, you can find the latest source tarball of libnl3 at http://www.carisma.slowglass.com/~tgr/libnl/ Disk replication: VMs protected by Remus need to use DRBD based disk backends. Specifically, you need a compile and install a custom version of DRBD, that is available publicly at https://github.com/rshriram/remus-drbd This code is based on DRBD 8.3.11 and uses a new replication protocol (named protocol D) for asynchronous disk checkpoint replication. A protected VM's DRBD disks on the primary and backup hosts need to be configured to use protocol D as the replication protocol. An example resource configuration file can be found in the aforementioned github repository.