[PATCH libvirt v1 3/6] conf: fix ZPCI address auto-generation on s390

Shalini Chellathurai Saroja shalini at linux.ibm.com
Tue Jun 16 10:43:18 UTC 2020


Hi Andrea,

Thank you for the review.

On 6/3/20 12:58 PM, Andrea Bolognani wrote:
> On Thu, 2020-04-09 at 12:31 +0200, Shalini Chellathurai Saroja wrote:
>> +++ b/src/conf/domain_addr.c
>> @@ -145,12 +145,18 @@ static void
>>   virDomainZPCIAddressReleaseIds(virDomainZPCIAddressIdsPtr zpciIds,
>>                                  virZPCIDeviceAddressPtr addr)
>>   {
>> -    if (!zpciIds || virZPCIDeviceAddressIsEmpty(addr))
>> +    if (!zpciIds)
>>           return;
>>   
>> -    virDomainZPCIAddressReleaseUid(zpciIds->uids, addr);
>> +    if (addr->uid_set) {
>> +        virDomainZPCIAddressReleaseUid(zpciIds->uids, addr);
>> +        addr->uid_set = false;
>> +    }
> I think it would be cleaner to handle the boolean flags in the same
> spot the values are taken care of, that is, in the Release{U,F}id()
> functions.
ok, I will do so.
>
>> @@ -186,12 +192,16 @@ static int
>>   virDomainZPCIAddressReserveAddr(virDomainZPCIAddressIdsPtr zpciIds,
>>                                   virZPCIDeviceAddressPtr addr)
>>   {
>> -    if (virDomainZPCIAddressReserveUid(zpciIds->uids, addr) < 0)
>> +    if (addr->uid_set &&
>> +        virDomainZPCIAddressReserveUid(zpciIds->uids, addr) < 0)
>>           return -1;
> Same here...
>
>>   
>> -    if (virDomainZPCIAddressReserveFid(zpciIds->fids, addr) < 0) {
>> -        virDomainZPCIAddressReleaseUid(zpciIds->uids, addr);
>> -        return -1;
>> +    if (addr->fid_set) {
>> +        if (virDomainZPCIAddressReserveFid(zpciIds->fids, addr) < 0) {
>> +            if (addr->uid_set)
>> +                virDomainZPCIAddressReleaseUid(zpciIds->uids, addr);
>> +            return -1;
>> +        }
>>       }
>>   
>>       return 0;
>> @@ -202,14 +212,28 @@ static int
>>   virDomainZPCIAddressReserveNextAddr(virDomainZPCIAddressIdsPtr zpciIds,
>>                                       virZPCIDeviceAddressPtr addr)
>>   {
>> -    if (virDomainZPCIAddressReserveNextUid(zpciIds->uids, addr) < 0)
>> -        return -1;
>> +    bool uid_set, fid_set = false;
>>   
>> -    if (virDomainZPCIAddressReserveNextFid(zpciIds->fids, addr) < 0) {
>> -        virDomainZPCIAddressReleaseUid(zpciIds->uids, addr);
>> -        return -1;
>> +    if (!addr->uid_set) {
>> +        if (virDomainZPCIAddressReserveNextUid(zpciIds->uids, addr) < 0)
>> +            return -1;
>> +        uid_set = true;
>> +    }
> ... and here. Basicall, push all handling of boolean flags one layer
> down, where the actual values are taken care of.
>
>> @@ -234,7 +258,7 @@ virDomainPCIAddressExtensionReserveNextAddr(virDomainPCIAddressSetPtr addrs,
>>                                               virPCIDeviceAddressPtr addr)
>>   {
>>       if (addr->extFlags & VIR_PCI_ADDRESS_EXTENSION_ZPCI) {
>> -        virZPCIDeviceAddress zpci = { 0 };
>> +        virZPCIDeviceAddress zpci = addr->zpci;
>>   
>>           if (virDomainZPCIAddressReserveNextAddr(addrs->zpciIds, &zpci) < 0)
>>               return -1;
>> @@ -246,6 +270,7 @@ virDomainPCIAddressExtensionReserveNextAddr(virDomainPCIAddressSetPtr addrs,
>>       return 0;
>>   }
>>   
>> +
>>   static int
>>   virDomainPCIAddressExtensionEnsureAddr(virDomainPCIAddressSetPtr addrs,
>>                                          virPCIDeviceAddressPtr addr)
>> @@ -253,10 +278,10 @@ virDomainPCIAddressExtensionEnsureAddr(virDomainPCIAddressSetPtr addrs,
>>       if (addr->extFlags & VIR_PCI_ADDRESS_EXTENSION_ZPCI) {
>>           virZPCIDeviceAddressPtr zpci = &addr->zpci;
>>   
>> -        if (virZPCIDeviceAddressIsEmpty(zpci))
>> -            return virDomainZPCIAddressReserveNextAddr(addrs->zpciIds, zpci);
>> -        else
>> -            return virDomainZPCIAddressReserveAddr(addrs->zpciIds, zpci);
>> +        if (virDomainZPCIAddressReserveAddr(addrs->zpciIds, zpci) < 0)
>> +            return -1;
>> +
>> +        return virDomainZPCIAddressReserveNextAddr(addrs->zpciIds, zpci);
>>       }
> I think the semantics for these functions need to be reconsidered.
>
> The way they currently work, as evidenced by EnsureAddr(), is that
> you either have a fully-specified address provided by the user, in
> which case you want to reserve that address, or you have an empty
> address because the user didn't provide ZPCI information, in which
> case you allocate a new full address based on what uids and fids are
> still available and use that one.
>
> With your changes, we can now find ourselves in a hybrid situation,
> where half of the ZPCI address has been provided by the user but the
> remaining half is up to us... Ultimately, it might make sense to have
> ReserveAddr(), ReserveNextAddr() and EnsureAddr() all call to the
> same function which does something along the lines of
>
>    if (!zpci->uid_set)
>        AssignUid(zpci);
>    if (!zpci->fid_set)
>        AssignFid(zpci);
>
>    ReserveUid(zpci);
>    ReserveFid(zpci);
>
> because that's ultimately what we're achieving anyway, only with
> more obfuscation.
ok, I will do so.
>> +++ b/src/conf/domain_conf.c
>> @@ -7471,7 +7471,7 @@ virDomainDeviceInfoFormat(virBufferPtr buf,
>>                                 virTristateSwitchTypeToString(info->addr.pci.multi));
>>           }
>>   
>> -        if (!virZPCIDeviceAddressIsEmpty(&info->addr.pci.zpci)) {
>> +        if (!virZPCIDeviceAddressIsIncomplete(&info->addr.pci.zpci)) {
>>               virBufferAsprintf(&childBuf,
>>                                 "<zpci uid='0x%.4x' fid='0x%.8x'/>\n",
>>                                 info->addr.pci.zpci.uid,
> By the time we get here, we should either have a complete ZPCI
> address or no ZPCI address at all. So I would rewrite this as
>
>    if (IsIncomplete(zpci))
>        virReportError(VIR_ERR_INTERNAL, ...);
>
>    if (!IsPresent(zpci))
>        virBufferAsprintf(...);
>
> with the first check being there just for extra safety (This Should
> Never Happen™).
Sure.
>
>> +++ b/src/util/virpci.h
>> @@ -43,6 +43,8 @@ typedef virZPCIDeviceAddress *virZPCIDeviceAddressPtr;
>>   struct _virZPCIDeviceAddress {
>>       unsigned int uid; /* exempt from syntax-check */
>>       unsigned int fid;
>> +    bool uid_set;
>> +    bool fid_set;
> I believe we mostly use camelCase for struct members, although I
> don't think we're too consistent with that :)
ok, I will camelCase the struct members.
>
> I wonder if it would make sense to tie the two bits of information
> together more explicitly, eg.
>
>    typedef struct _virZPCIDeviceAddressID {
>        unsigned int value;
>        bool isSet;
>    } virZPCIDeviceAddressID;
>
>    typedef struct _virZPCIDeviceAddress {
>        virZPCIDeviceAddressID uid;
>        virZPCIDeviceAddressID fid;
>    } virZPCIDeviceAddress;
I will redefine the struct as above.
>
>> +++ b/tests/qemuxml2xmloutdata/hostdev-vfio-zpci-multidomain-many.xml
>> @@ -39,7 +39,7 @@
>>           <address domain='0x0003' bus='0x00' slot='0x00' function='0x0'/>
>>         </source>
>>         <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'>
>> -        <zpci uid='0x0001' fid='0x00000001'/>
>> +        <zpci uid='0x0001' fid='0x00000000'/>
>>         </address>
>>       </hostdev>
>>       <hostdev mode='subsystem' type='pci' managed='no'>
>> @@ -48,7 +48,7 @@
>>           <address domain='0x0004' bus='0x00' slot='0x00' function='0x0'/>
>>         </source>
>>         <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'>
>> -        <zpci uid='0x0002' fid='0x00000002'/>
>> +        <zpci uid='0x0002' fid='0x00000001'/>
>>         </address>
>>       </hostdev>
>>       <hostdev mode='subsystem' type='pci' managed='no'>
>> @@ -57,7 +57,7 @@
>>           <address domain='0x0005' bus='0x00' slot='0x00' function='0x0'/>
>>         </source>
>>         <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'>
>> -        <zpci uid='0x0053' fid='0x00000000'/>
>> +        <zpci uid='0x0053' fid='0x00000002'/>
> I'm not entirely clear on why these generated ZPCI addresses would
> change. Can you explain that to me?

Sure:-). It changes in this version because at first the user specified 
addresses are reserved and then the addresses which are not specified by 
the user are assigned and reserved.

In the current master code, as uid and fid are correlated, both uid and 
fid are reserved, when either one of them is specified by the user. So 
for the pci device with uid =  '0x0053', the code assumes that user has 
specified fid as 0 (which is not true) and reserves fid as 0.

Warm Regards

Shalini C S



>





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