[kvm-devel] Setting hardware breakpoints in guest OS

[<du...@so...>]

Can hardware breakpoints be set (and trapped, and handled) inside a guest
OS (specifially Windows XP2)?

I noticed the other day that software (malicious code, in fact) packed with
the EXE compressor PELock won't run under QEMU+KVM. I guessed that this was
because h/w breakpoints aren't being trapped. (The PELock incarnation used
in this case relies on SEH and H/W breaks -- verifying that they take place
correctly -- in its decryption code in order to try to make it harder to
extract the original content from packed files.)

A quick try with OllyDbg suggested that I wasn't able to provoke hardware
traps in my own code, either. Olly allows me to specify a H/W breakpoint
but I never seem to get control back at the desired address. INT 1 and INT
3 debugging work just fine (i.e. tracing and software breakpoints).

Is this "one of those things" to do with virtualisation? QEMU+kqemu handles
PELock files just fine.

Apologies if this is an already-answered question. I couldn't find an
answer on my own.