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From: Claudio Imbrenda <imbrenda@linux.ibm.com>
To: Janosch Frank <frankja@linux.ibm.com>
Cc: kvm@vger.kernel.org, thuth@redhat.com, david@redhat.com,
	nrb@linux.ibm.com, scgl@linux.ibm.com, seiden@linux.ibm.com
Subject: Re: [kvm-unit-tests PATCH v1 0/5] s390x: smp: avoid hardcoded CPU addresses
Date: Thu, 3 Feb 2022 16:48:00 +0100	[thread overview]
Message-ID: <20220203164800.732ad674@p-imbrenda> (raw)
In-Reply-To: <9a38563e-3307-13df-e734-483a31822e08@linux.ibm.com>

On Thu, 3 Feb 2022 16:23:23 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

> On 2/3/22 14:37, Claudio Imbrenda wrote:
> > On Thu, 3 Feb 2022 09:45:56 +0100
> > Janosch Frank <frankja@linux.ibm.com> wrote:
> >   
> >> On 1/28/22 19:54, Claudio Imbrenda wrote:  
> >>> On s390x there are no guarantees about the CPU addresses, except that
> >>> they shall be unique. This means that in some environments, it's
> >>> possible that there is no match between the CPU address and its
> >>> position (index) in the list of available CPUs returned by the system.  
> >>
> >> While I support this patch set I've yet to find an environment where
> >> this gave me headaches.
> >>  
> >>>
> >>> This series fixes a small bug in the SMP initialization code, adds a
> >>> guarantee that the boot CPU will always have index 0, and introduces
> >>> some functions to allow tests to use CPU indexes instead of using
> >>> hardcoded CPU addresses. This will allow the tests to run successfully
> >>> in more environments (e.g. z/VM, LPAR).  
> >>
> >> I'm wondering if we should do it the other way round and make the smp_*
> >> functions take a idx instead of a cpu addr. The only instance where this
> >> gets a bit ugly is the sigp calls which we would also need to convert.  
> > 
> > yes, in fact this is something I was already planning to do :)  
> 
> Do you want to add that in a v2 to reduce the additional churn?

ok

> 
> > 
> > for sigp, we can either convert, or add a wrapper with idx.  
> 
> How about adding a wrapper to smp.c?
> 
> smp_cpu_sigp()
> smp_cpu_sigp_retry()

I was actually thinking about sigp_idx, but I like your names better

> 
> 
> That would fall in line with the naming of the smp functions and it's 
> clear that we refer to a specific cpu from the smp lib.
> 
> We can then leave the sigp.h functions as is so Nico can use them for 
> the invalid addr tests.

yes, a "raw" sigp function should definitely stay there

> 
> >   
> >>  
> >>> Some existing tests are adapted to take advantage of the new
> >>> functionalities.
> >>>
> >>> Claudio Imbrenda (5):
> >>>     lib: s390x: smp: add functions to work with CPU indexes
> >>>     lib: s390x: smp: guarantee that boot CPU has index 0
> >>>     s390x: smp: avoid hardcoded CPU addresses
> >>>     s390x: firq: avoid hardcoded CPU addresses
> >>>     s390x: skrf: avoid hardcoded CPU addresses
> >>>
> >>>    lib/s390x/smp.h |  2 ++
> >>>    lib/s390x/smp.c | 28 ++++++++++++-----
> >>>    s390x/firq.c    | 17 +++++-----
> >>>    s390x/skrf.c    |  8 +++--
> >>>    s390x/smp.c     | 83 ++++++++++++++++++++++++++-----------------------
> >>>    5 files changed, 79 insertions(+), 59 deletions(-)
> >>>      
> >>  
> >   
> 


  reply	other threads:[~2022-02-03 15:48 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-28 18:54 [kvm-unit-tests PATCH v1 0/5] s390x: smp: avoid hardcoded CPU addresses Claudio Imbrenda
2022-01-28 18:54 ` [kvm-unit-tests PATCH v1 1/5] lib: s390x: smp: add functions to work with CPU indexes Claudio Imbrenda
2022-01-31 13:50   ` David Hildenbrand
2022-02-02 16:55     ` Steffen Eiden
2022-02-03 13:33     ` Claudio Imbrenda
2022-01-28 18:54 ` [kvm-unit-tests PATCH v1 2/5] lib: s390x: smp: guarantee that boot CPU has index 0 Claudio Imbrenda
2022-01-31 13:55   ` David Hildenbrand
2022-02-03 11:41     ` Claudio Imbrenda
2022-01-28 18:54 ` [kvm-unit-tests PATCH v1 3/5] s390x: smp: avoid hardcoded CPU addresses Claudio Imbrenda
2022-01-28 18:54 ` [kvm-unit-tests PATCH v1 4/5] s390x: firq: " Claudio Imbrenda
2022-01-28 18:54 ` [kvm-unit-tests PATCH v1 5/5] s390x: skrf: " Claudio Imbrenda
2022-02-03  8:45 ` [kvm-unit-tests PATCH v1 0/5] s390x: smp: " Janosch Frank
2022-02-03 13:37   ` Claudio Imbrenda
2022-02-03 15:23     ` Janosch Frank
2022-02-03 15:48       ` Claudio Imbrenda [this message]
2022-02-04 15:01 ` Janosch Frank
2022-02-04 15:14   ` Claudio Imbrenda
2022-02-04 15:37     ` Janosch Frank

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