Re: [PATCH] kvm-userspace: x86: Support for breakpoints in ROM code

[Jan Kiszka <jan.kiszka@siemens.com>]

Avi Kivity wrote:
> Jan Kiszka wrote:
>> Jan Kiszka wrote:
>>  
>>> Align qemu-kvm-x86 with upstream kvm support /wrt software breakpoint
>>> support in ROM code.
>>>     
>>
>> Hmm, this might not be needed as kvm-userspace is not protecting its
>> ROM. That's why I didn't pushed this so far. However, aligning isn't
>> bad. But dropping this duplication would be better...
>>   
> 
> Aligning is a good thing (and duplication can be fixed in upstream and
> merged here).  But maybe cpu_memory_rw_debug() should use
> cpu_physical_memory_write_rom() to write, instead of this hack?

This is not a hack (it shouldn't have been merged upstream otherwise):
cpu_physical_memory_write_rom() takes system-wide physical addresses
while kvm_patch_opcode_byte() works with per-CPU linear addresses.

And IMHO, the duplication needs to be fixed here by switching to
upstream's kvm layer - at some point in the future. As a first step, we
may have to look in making them compatible so that you can use the both
layers at the same time.

Jan

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