xen-hvmcrash would previously save records, overwrite the instruction
pointer with a bogus value, and then restore them to crash a domain
just enough to cause the guest OS to memdump.
This approach is found to be unreliable when tested on a guest running
Windows 10 x64, with some executions doing nothing at all.
Another approach would be to trigger NMIs. This approach is found to be
unreliable when tested on Linux (Ubuntu 22.04), as Linux will ignore
NMIs if it is not configured to handle such.
Injecting a double fault abort to all vCPUs is found to be more
reliable at crashing and invoking memdumps from Windows and Linux
domains.
This patch modifies the xen-hvmcrash tool to inject #DF to all vCPUs
belonging to the specified domain, instead of overwriting RIP.
Signed-off-by: Matthew Barnes <matthew.barnes@cloud.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
This tool reads the CPU save records, overwrites RIP with a bogus
value, and then restores them. This is, of course, not guaranteed
to crash the guest (since the CPUs may not be executing in kernel
at the time) but it's good for breaking into some tight loops that
would be hard to debug otherwise.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Matthew Barnes