On 2024/3/24 上午2:40, WANG Xuerui wrote:
On 3/15/24 16:11, Bibo Mao wrote:
[snip]
+KVM hypercall ABI
+=================
+
+Hypercall ABI on KVM is simple, only one scratch register a0 and at most
+five generic registers used as input parameter. FP register and
vector register
+is not used for input register and should not be modified during
hypercall.
+Hypercall function can be inlined since there is only one scratch
register.
Maybe it's better to describe the list of preserved registers with an
expression such as "all non-GPR registers shall remain unmodified after
returning from the hypercall", to guard ourselves against future ISA
state additions.
Sorry, I do not understand. What is the meaning of "all non-GPR
registers"? Can you give an example?
Regards
Bibo Mao
But I still maintain that it's better to promise less here, and only
hint on the extensive preservation of context as an implementation
detail. It is for not losing our ability to save/restore less in the
future, should we decide to do so.
