From: Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: [EXT] Re: vmm(4)/amd64: reduce use of extern
To: Hans-Jörg Höxer <hshoexer@genua.de>
Cc: tech@openbsd.org
Date: Mon, 28 Apr 2025 17:02:41 +0200

> Date: Mon, 28 Apr 2025 15:25:48 +0200
> From: Hans-Jörg Höxer <hshoexer@genua.de>
> 
> Hi,
> 
> On Mon, Apr 28, 2025 at 01:20:15PM +0200, Mark Kettenis wrote:
> > > Date: Mon, 28 Apr 2025 12:57:18 +0200
> > > From: Hans-Jörg Höxer <hshoexer@genua.de>
> > > 
> > > Hi,
> > > 
> > > this diff reduces the use of "extern" in amd64/vmm_machdep.c and related
> > > files.  There might be some more low hanging fruits in eg. pmap.c.
> > 
> > The problem is that <machine/cpu.h> ends up getting included by a lot
> > of files (even from userland).  So there is a big risk of namespace
> > pollution.  This is somewhat mitigated by #ifdef _KERNEL, but some of
> > the userland code in base does do a #define _KERNEL.  It is also
> > mitigated by using a cpu_ prefix for the symbol names.
> 
> I see and agree.  New approach:  Diff below just deals with
> amd64/vmm_machdep.c and varibles declared in dev/vmm.c.  I'd suggest
> to declare those in dev/vmm.h.  Future implementations of vmm_machdep.c
> eg. for arm64 will likely need those, too.

Cool, yes, I think that's fine.  Maybe give dv@ or mlarkin@ a couple
of days to protest ;).

ok kettenis@

> ----------------------------------------------------------------------------
> commit dd3e5f229f00bc357b1121ed56180b8c0a87124d
> Author: Hans-Joerg Hoexer <hshoexer@genua.de>
> Date:   Mon Apr 28 15:15:07 2025 +0200
> 
>     vmm(4)/amd64: reduce use of extern
> 
> diff --git a/sys/arch/amd64/amd64/vmm_machdep.c b/sys/arch/amd64/amd64/vmm_machdep.c
> index 9b5d56da27b..c9a2f8b73f9 100644
> --- a/sys/arch/amd64/amd64/vmm_machdep.c
> +++ b/sys/arch/amd64/amd64/vmm_machdep.c
> @@ -193,9 +193,6 @@ const struct kmem_pa_mode vmm_kp_contig = {
>  	.kp_zero = 1,
>  };
>  
> -extern struct cfdriver vmm_cd;
> -extern const struct cfattach vmm_ca;
> -
>  /*
>   * Helper struct to easily get the VMCS field IDs needed in vmread/vmwrite
>   * to access the individual fields of the guest segment registers. This
> @@ -225,12 +222,6 @@ const struct {
>  	  VMCS_GUEST_IA32_TR_AR, VMCS_GUEST_IA32_TR_BASE }
>  };
>  
> -/* Pools for VMs and VCPUs */
> -extern struct pool vm_pool;
> -extern struct pool vcpu_pool;
> -
> -extern struct vmm_softc *vmm_softc;
> -
>  /* IDT information used when populating host state area */
>  extern vaddr_t idt_vaddr;
>  extern struct gate_descriptor *idt;
> diff --git a/sys/dev/vmm/vmm.h b/sys/dev/vmm/vmm.h
> index 00cf820c9f1..f27433b9e1b 100644
> --- a/sys/dev/vmm/vmm.h
> +++ b/sys/dev/vmm/vmm.h
> @@ -228,6 +228,12 @@ struct vmm_softc {
>  	uint8_t			vpids[512];	/* [p] bitmap of VPID/ASIDs */
>  };
>  
> +extern struct vmm_softc *vmm_softc;
> +extern struct pool vm_pool;
> +extern struct pool vcpu_pool;
> +extern struct cfdriver vmm_cd;
> +extern const struct cfattach vmm_ca;
> +
>  int vmm_probe(struct device *, void *, void *);
>  int vmm_activate(struct device *, int);
>  void vmm_attach(struct device *, struct device *,  void *);
> 
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>