Re: [PATCH 12/32] s390/pci: get SHM information from list pci

[Matthew Rosato]

On 12/8/21 7:21 AM, Niklas Schnelle wrote:
> On Tue, 2021-12-07 at 15:57 -0500, Matthew Rosato wrote:
> > KVM will need information on the special handle mask used to indicate
> > emulated devices.  In order to obtain this, a new type of list pci call
> > must be made to gather the information.  Remove the unused data pointer
> > from clp_list_pci and __clp_add and instead optionally pass a pointer to
> > a model-dependent-data field.  Additionally, allow for clp_list_pci calls
> > that don't specify a callback - in this case, just do the first pass of
> > list pci and exit.
> >
> > Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
> > ---
> >   arch/s390/include/asm/pci.h     |  6 ++++++
> >   arch/s390/include/asm/pci_clp.h |  2 +-
> >   arch/s390/pci/pci.c             | 19 +++++++++++++++++++
> >   arch/s390/pci/pci_clp.c         | 16 ++++++++++------
> >   4 files changed, 36 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
> > index 00a2c24d6d2b..86f43644756d 100644
> > --- a/arch/s390/include/asm/pci.h
> > +++ b/arch/s390/include/asm/pci.h
> > @@ -219,12 +219,18 @@ int zpci_unregister_ioat(struct zpci_dev *, u8);
> >   void zpci_remove_reserved_devices(void);
> >   void zpci_update_fh(struct zpci_dev *zdev, u32 fh);
> ---8<---
> > -static int clp_list_pci(struct clp_req_rsp_list_pci *rrb, void *data,
> > -			void (*cb)(struct clp_fh_list_entry *, void *))
> > +int clp_list_pci(struct clp_req_rsp_list_pci *rrb, u32 *mdd,
> > +		 void (*cb)(struct clp_fh_list_entry *))
> >   {
> >   	u64 resume_token = 0;
> >   	int nentries, i, rc;
> > @@ -368,8 +368,12 @@ static int clp_list_pci(struct clp_req_rsp_list_pci *rrb, void *data,
> >   		rc = clp_list_pci_req(rrb, &resume_token, &nentries);
> >   		if (rc)
> >   			return rc;
> > +		if (mdd)
> > +			*mdd = rrb->response.mdd;
> > +		if (!cb)
> > +			return 0;
>
> I think it would be slightly cleaner to instead de-static
> clp_list_pci_req() and call that directly. Just because that makes the
> clp_list_pci() still list all PCI functions and allows us to get rid of
> the data parameter completely.

Oops, I must have missed this comment before.  Sure, makes sense.

> Also, I've been thinking about moving clp_scan_devices(),
> clp_get_state(), and clp_refresh_fh() out of pci_clp.c because they are
> higher level. I think that would nicely fit your zpci_get_mdd() in
> pci.c with or without the above suggestion. Then we could do the
> removal of the unused data parameter in that series as a cleanup. What
> do you think?

Sure, that would be fine.  So then this patch instead just exports 
alloc/free/clp_list_pci_req and the new zpci_get_mdd calls 
clp_list_pci_req directly.  I'll drop the changes to clp_list_pci() and 
__clp_add (and re-word the commit message)

> >   		for (i = 0; i < nentries; i++)
> > -			cb(&rrb->response.fh_list[i], data);
> > +			cb(&rrb->response.fh_list[i]);
> >   	} while (resume_token);
> >   
> >   	return rc;
> > @@ -398,7 +402,7 @@ static int clp_find_pci(struct clp_req_rsp_list_pci *rrb, u32 fid,
> >   	return -ENODEV;
> >   }
> >   
> > -static void __clp_add(struct clp_fh_list_entry *entry, void *data)
> > +static void __clp_add(struct clp_fh_list_entry *entry)
> >   {
> >   	struct zpci_dev *zdev;
> >