On 28.08.2024 16:44, Andrew Cooper wrote:
> On 27/08/2024 5:07 pm, Jan Beulich wrote:
>> On 27.08.2024 15:57, Andrew Cooper wrote:
>>> + for_each_set_bit ( seg, dirty )
>>> + hvm_set_segment_register(curr, seg, &hvmemul_ctxt->seg_reg[seg]);
>>> +
>>> + hvmemul_ctxt->seg_reg_dirty = 0;
>> Why is this suddenly appearing here? You don't mention it in the description,
>> so it's not clear whether you found a (however minor) issue, or whether
>> that's purely cosmetic (yet then it's still an extra store we could do
>> without).
>
> Oh, yes. Nothing anywhere in Xen ever clears these segment dirty bits.
hvm_emulate_init_once()?
> I suspect the worst that will go wrong is that we'll waste time
> re-{VMWRITE,memcpy}-ing the segment registers into the VMCS/VMCB, but
> the logic in Xen is definitely not right.
I'm on the edge of asking to do such clearing before emulation, not after
processing the dirty bits. That would then be hvm_emulate_init_per_insn(),
well centralized.
Jan
