Re: [RFC 14/14] KVM: s390: Allow the VSIE to be used with huge pages

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

 



On 9/19/18 10:56 AM, David Hildenbrand wrote:
> Am 19.09.18 um 10:48 schrieb Janosch Frank:
>> Now that we have VSIE support for VMs with huge memory backing, let's
>> make both features usable at the same time.
>>
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> ---
>>  Documentation/virtual/kvm/api.txt |  7 +++----
>>  arch/s390/kvm/kvm-s390.c          | 14 ++------------
>>  arch/s390/mm/gmap.c               |  1 -
>>  3 files changed, 5 insertions(+), 17 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index 8d8a372c8340..9ec6d23f41d5 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -4509,15 +4509,14 @@ Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits.
>>  
>>  Architectures: s390
>>  Parameters: none
>> -Returns: 0 on success, -EINVAL if hpage module parameter was not set
>> -	 or cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL
>> +Returns: 0 on success, -EINVAL if cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL
>>  	 flag set
>>  
>>  With this capability the KVM support for memory backing with 1m pages
>>  through hugetlbfs can be enabled for a VM. After the capability is
>>  enabled, cmma can't be enabled anymore and pfmfi and the storage key
>> -interpretation are disabled. If cmma has already been enabled or the
>> -hpage module parameter is not set to 1, -EINVAL is returned.
>> +interpretation are disabled. If cmma has already been enabled, -EINVAL
>> +is returned.
>>  
>>  While it is generally possible to create a huge page backed VM without
>>  this capability, the VM will not be able to run.
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index ac5da6b0b862..59f53b7c72d6 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -172,11 +172,6 @@ static int nested;
>>  module_param(nested, int, S_IRUGO);
>>  MODULE_PARM_DESC(nested, "Nested virtualization support");
>>  
>> -/* allow 1m huge page guest backing, if !nested */
>> -static int hpage;
>> -module_param(hpage, int, 0444);
>> -MODULE_PARM_DESC(hpage, "1m huge page backing support");
>> -
> 
> 
> Do we want to keep the parameter for now?
> 
> This would allow admins to disable it system-wide as long as it is in
> its early stage? (just like nested). We can allow co-existence, though.

Both options are fine with me and considering the fixes needed for the
enablement this might be the better option.

> 
>>  /*
>>   * For now we handle at most 16 double words as this is what the s390 base
>>   * kernel handles and stores in the prefix page. If we ever need to go beyond
>> @@ -481,7 +476,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>  		break;
>>  	case KVM_CAP_S390_HPAGE_1M:
>>  		r = 0;
>> -		if (hpage && !kvm_is_ucontrol(kvm))
>> +		if (!kvm_is_ucontrol(kvm))
>>  			r = 1;
>>  		break;
>>  	case KVM_CAP_S390_MEM_OP:
>> @@ -691,7 +686,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
>>  		mutex_lock(&kvm->lock);
>>  		if (kvm->created_vcpus)
>>  			r = -EBUSY;
>> -		else if (!hpage || kvm->arch.use_cmma || kvm_is_ucontrol(kvm))
>> +		else if (kvm->arch.use_cmma || kvm_is_ucontrol(kvm))
>>  			r = -EINVAL;
>>  		else {
>>  			r = 0;
>> @@ -4196,11 +4191,6 @@ static int __init kvm_s390_init(void)
>>  		return -ENODEV;
>>  	}
>>  
>> -	if (nested && hpage) {
>> -		pr_info("nested (vSIE) and hpage (huge page backing) can currently not be activated concurrently");
>> -		return -EINVAL;
>> -	}
>> -
>>  	for (i = 0; i < 16; i++)
>>  		kvm_s390_fac_base[i] |=
>>  			S390_lowcore.stfle_fac_list[i] & nonhyp_mask(i);
>> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
>> index 8d5ce51637eb..928cb5818a21 100644
>> --- a/arch/s390/mm/gmap.c
>> +++ b/arch/s390/mm/gmap.c
>> @@ -1830,7 +1830,6 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
>>  	unsigned long limit;
>>  	int rc;
>>  
>> -	BUG_ON(parent->mm->context.allow_gmap_hpage_1m);
>>  	BUG_ON(gmap_is_shadow(parent));
>>  	spin_lock(&parent->shadow_lock);
>>  	sg = gmap_find_shadow(parent, asce, edat_level);
>>
> 


Attachment: signature.asc
Description: OpenPGP digital signature


[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