Re: [PATCH v3 00/13] xen: drop hypercall function tables

[Jan Beulich <jbeulich@xxxxxxxx>]

On 08.12.2021 16:55, Juergen Gross wrote:
> In order to avoid indirect function calls on the hypercall path as
> much as possible this series is removing the hypercall function tables
> and is replacing the hypercall handler calls via the function array
> by automatically generated call macros.
> 
> Another by-product of generating the call macros is the automatic
> generating of the hypercall handler prototypes from the same data base
> which is used to generate the macros.
> 
> This has the additional advantage of using type safe calls of the
> handlers and to ensure related handler (e.g. PV and HVM ones) share
> the same prototypes.
> 
> A very brief performance test (parallel build of the Xen hypervisor
> in a 6 vcpu guest) showed a very slim improvement (less than 1%) of
> the performance with the patches applied. The test was performed using
> a PV and a PVH guest.
> 
> Changes in V2:
> - new patches 6, 14, 15
> - patch 7: support hypercall priorities for faster code
> - comments addressed
> 
> Changes in V3:
> - patches 1 and 4 removed as already applied
> - comments addressed
> 
> Juergen Gross (13):
>   xen: move do_vcpu_op() to arch specific code
>   xen: harmonize return types of hypercall handlers
>   xen: don't include asm/hypercall.h from C sources
>   xen: include compat/platform.h from hypercall.h
>   xen: generate hypercall interface related code
>   xen: use generated prototypes for hypercall handlers
>   x86/pv-shim: don't modify hypercall table
>   xen/x86: don't use hypercall table for calling compat hypercalls
>   xen/x86: call hypercall handlers via generated macro
>   xen/arm: call hypercall handlers via generated macro
>   xen/x86: add hypercall performance counters for hvm, correct pv
>   xen: drop calls_to_multicall performance counter
>   tools/xenperf: update hypercall names

As it's pretty certain now that parts of this which didn't go in yet will
need re-basing, I'm going to drop this from my waiting-to-be-acked folder,
expecting a v4 instead.

Jan