Re: SEV guest debugging support for Qemu

[Paolo Bonzini <pbonzini@redhat.com>]

On 25/09/20 22:46, Ashish Kalra wrote:
> I was also considering abstracting this vendor/SEV specific debug
> interface via the CPUClass object, the CPUClass object aleady has cpu
> specific methods for doing things like guest VA to GPA translations like the
> get_phys_page_attrs_debug() method and it will be a simple and clean
> approach to override this method with a SEV specific
> get_phys_page_attrs_debug() if SEV guest is active and SEV debug policy
> is allowed. [...]
> 
> I can probably add new interfaces/methods to this CPUClass object for
> guest memory read/writes for debugging purpose and then invoke the same
> from the generic cpu_memory_rw_debug() interface. 
> 
> Let me know your thougts on abstracting this debug interface via the
> CPUClass object ? 
> 
> Or the other option is to introduce the new MemoryDebugOps you described
> above and additionally apply SEV/SEV-ES considerations in CPUClass
> methods such as gdb_read_register, gdb_write_register, etc.

Yes, this makes the most sense, however you're right that you don't need
translate in MemoryDebugOps.  I don't think read/write should be moved
to CPUClass, however, since you can use a MemTxAttr to tell the
read/write MemoryDebugOps whether the page is encrypted or not.

Paolo