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

[Matthew Rosato <mjrosato@linux.ibm.com>]

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@linux.ibm.com>
>> ---
>>   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;
>>   
>