Re: Qemu TCG Plugins - how to access guest registers?

[Lukas Straub]

On Fri, 27 Mar 2020 15:40:38 -0600
Benjamin <address@hidden> wrote:

> Qemu version 4.2.0 includes new functionality for something called TCG
> Plugins. There are a few examples in the tests/plugins directory, and the
> API is more or less defined in qemu-plugin.h.
> 
> This file defines two enumerated types, "qemu_plugin_cb_flags" and
> "qemu_plugin_mem_rw", which are passed into functions that register
> callbacks. These enums seem to indicate whether the callbacks will read or
> write CPU registers or memory. However, all of the example plugins use
> "QEMU_PLUGIN_CB_NO_REGS", and only 2 of the plugins use the memory access
> enum. hotpages.c and mem.c use "QEMU_PLUGIN_MEM_RW" as the default for
> registering a memory callback (qemu_plugin_register_vcpu_mem_cb). mem.c has
> an argument when the plugin is loaded to choose if it's read or write,
> however, it doesn't seem to make any difference in the callback function.
> 
> My question is, how do I access the guest memory and registers from the
> plugin callback function? The API seems to indicate that it is possible,
> since the callback registering requires you to say if you will access them,
> and if it's RW or just read.
> 
> Are there any examples of using this part of the API? I realize this is a
> very new part of Qemu functionality.
> 
> Thanks

CC'ing the maintainer of TCG Plugins.

pgpZri6lJvvps.pgp
Description: OpenPGP digital signature