Re: [Xen-devel] [PATCH v2 4/9] x86/pv: Implement pv_hypercall() in C

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.09.16 at 12:12, <andrew.cooper3@xxxxxxxxxx> wrote:
> In a similar style to hvm_do_hypercall().  The C version is far easier to
> understand and edit than the assembly versions.
> 
> There are a few small differences however.  The register clobbering values
> have changed (to match the HVM side), and in particular clobber the upper
> 32bits of 64bit arguments.  The hypercall and performance counter record are
> reordered to increase code sharing between the 32bit and 64bit cases.
> 
> The sole callers of __trace_hypercall_entry() were the assembly code.  Given
> the new C layout, it is more convenient to fold __trace_hypercall_entry() into
> pv_hypercall(), and call __trace_hypercall() directly.
> 
> Finally, pv_hypercall() will treat a NULL hypercall function pointer as
> -ENOSYS, allowing further cleanup.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>


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