Re: [PATCH v7 3/3] s390/kvm: diagnose 0x318 get/set handling

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 5/18/20 5:15 AM, Christian Borntraeger wrote:
> 
> 
> On 16.05.20 00:19, Collin Walling wrote:
>> DIAGNOSE 0x318 (diag 318) sets information regarding the environment
>> the VM is running in (Linux, z/VM, etc) and is observed via
>> firmware/service events.
>>
>> This is a privileged s390x instruction that must be intercepted by
>> SIE. Userspace handling is required, so let's introduce some functions
>> to communicate between userspace and KVM via ioctls. These will be used
>> to get/set the diag 318 related information.
>>
>> The Control Program Name Code (CPNC) is stored in the SIE block. The
>> CPNC along with the Control Program Version Code (CPVC) are stored in
>> the kvm_arch struct.
>>
>> Signed-off-by: Collin Walling <walling@xxxxxxxxxxxxx>
>> ---
>>  Documentation/virt/kvm/devices/vm.rst | 21 +++++++
>>  arch/s390/include/asm/kvm_host.h      |  5 +-
>>  arch/s390/include/uapi/asm/kvm.h      |  4 ++
>>  arch/s390/kvm/kvm-s390.c              | 82 +++++++++++++++++++++++++++
>>  arch/s390/kvm/vsie.c                  |  2 +
>>  5 files changed, 113 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/virt/kvm/devices/vm.rst b/Documentation/virt/kvm/devices/vm.rst
>> index 0aa5b1cfd700..52cc906dd7bd 100644
>> --- a/Documentation/virt/kvm/devices/vm.rst
>> +++ b/Documentation/virt/kvm/devices/vm.rst
>> @@ -314,3 +314,24 @@ Allows userspace to query the status of migration mode.
>>  	     if it is enabled
>>  :Returns:   -EFAULT if the given address is not accessible from kernel space;
>>  	    0 in case of success.
>> +
>> +6. GROUP: KVM_S390_VM_MISC
>> +==========================
>> +
>> +:Architectures: s390
>> +
>> +6.1. KVM_S390_VM_MISC_DIAG_318 (r/w)
>> +-----------------------------------
>> +
>> +Allows userspace to retrieve and set the DIAGNOSE 0x318 information,
>> +which consists of a 1-byte "Control Program Name Code" and a 7-byte
>> +"Control Program Version Code" (a 64 bit value all in all). This
>> +information is set by the guest (usually during IPL). This interface is
>> +intended to allow retrieving and setting it during migration; while no
>> +real harm is done if the information is changed outside of migration,
>> +it is strongly discouraged.
>> +
>> +:Parameters: address of a buffer in user space (u64), where the
>> +	     information is read from or stored into
>> +:Returns:    -EFAULT if the given address is not accessible from kernel space;
>> +	     0 in case of success
> 
> 
> An alternative would be a new sync_reg value + KVM capability.
> 
> 

I did some investigation into this (new grounds for me)

sync_reg would handle the migration part, and then we'd just need the
ioctl so the diag instruction handler can set the data. Does that sound
right?

-- 
Regards,
Collin

Stay safe and stay healthy



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Kernel Development]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Info]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Linux Media]     [Device Mapper]

  Powered by Linux