Re: git: 76887e84be97 - main - cpuset: increase userland maximum size to 1024

From: John Baldwin <jhb_at_FreeBSD.org>
Date: Wed, 10 May 2023 17:29:53 UTC 
On 5/9/23 2:40 AM, Corvin Köhne wrote:
> On Tue, 2023-05-09 at 09:43 +0200, Corvin Köhne wrote:
>> On Tue, 2023-05-09 at 08:59 +0200, Corvin Köhne wrote:
>>> On Mon, 2023-05-08 at 18:26 +0000, Ed Maste wrote:
>>>> The branch main has been updated by emaste:
>>>>
>>>> URL:
>>>> https://cgit.FreeBSD.org/src/commit/?id=76887e84be975698b14699d7d0dfb157d73e9990
>>>>
>>>> commit 76887e84be975698b14699d7d0dfb157d73e9990
>>>> Author:     Ed Maste <emaste@FreeBSD.org>
>>>> AuthorDate: 2023-05-02 20:57:12 +0000
>>>> Commit:     Ed Maste <emaste@FreeBSD.org>
>>>> CommitDate: 2023-05-08 18:25:15 +0000
>>>>
>>>>      cpuset: increase userland maximum size to 1024
>>>>      
>>>>      Hardware with more than 256 CPU cores is now available and
>>>> will
>>>> become
>>>>      increasingly common.  Bump CPU_MAXSIZE (used for userland
>>>> cpuset_t
>>>>      sizing) to 1024 to define the ABI for FreeBSD 14.
>>>>      
>>>>      PR:             269572, 271213 [exp-run]
>>>>      Reviewed by:    mjg, jhb
>>>>      Relnotes:       yes
>>>>      Sponsored by:   The FreeBSD Foundation
>>>>      Differential Revision: https://reviews.freebsd.org/D39941
>>>> ---
>>>>   sys/sys/_cpuset.h | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/sys/sys/_cpuset.h b/sys/sys/_cpuset.h
>>>> index b75ee595da3c..676f9855f384 100644
>>>> --- a/sys/sys/_cpuset.h
>>>> +++ b/sys/sys/_cpuset.h
>>>> @@ -40,7 +40,7 @@
>>>>   #define        CPU_SETSIZE     MAXCPU
>>>>   #endif
>>>>   
>>>> -#define        CPU_MAXSIZE     256
>>>> +#define        CPU_MAXSIZE     1024
>>>>   
>>>>   #ifndef        CPU_SETSIZE
>>>>   #define        CPU_SETSIZE     CPU_MAXSIZE
>>>
>>> Hi Ed,
>>>
>>> this somehow breaks bhyve on my system. It immediately exits with
>>> "vm_run error -1" on startup.
>>>
>>>
>>
>> Setting MAXCPU [1] to 1024 as well, solves the issue. Not sure if
>> it's
>> a regression of your commit or a bhyve bug.
>>
>> [1]
>> https://github.com/freebsd/freebsd-src/blob/20d8d9809a8c0a3ddd1d0156e77ec53a1ed95747/sys/amd64/include/param.h#L68
>>
>>
> 
> vmm kernel module and bhyve userland are sharing a cpuset_t. So, this
> commit introduces a mismatch in the ioctl signature of VM_RUN. Any
> advice how to fix this properly, would be appreciated.

The ioctl needs to change to follow the pattern all the syscalls that
use cpuset_t do: take a pointer to the cpuset_t and a size instead of
embedding the cpuset_t in the ioctl structure.  We will have to define
a COMPAT_FREEBSD13 structure and ioctl with the current structure with
a hardcoded cpuset_t size (probably just inline cpuset_t member as an
anonymous struct with the same members as cpuset_t but a constant for
the array count) as well.

-- 
John Baldwin