Re: [PATCH v7] KVM: s390: Add new reset vcpu API

[Janosch Frank <frankja@xxxxxxxxxxxxx>]

On 1/27/20 9:05 AM, Christian Borntraeger wrote:
> 
> 
> On 10.01.20 12:45, Janosch Frank wrote:
> [...]
>> +static void kvm_arch_vcpu_ioctl_clear_reset(struct kvm_vcpu *vcpu)
>> +{
>> +	struct kvm_sync_regs *regs = &vcpu->run->s.regs;
>> +
>> +	/* Clear reset is a superset of the initial reset */
>> +	kvm_arch_vcpu_ioctl_normal_reset(vcpu);
>> +
>> +	memset(&regs->gprs, 0, sizeof(regs->gprs));
> 
> 
> 
>> +	/* Will be picked up because of save_fpu_regs() in the initial reset */
>> +	memset(&current->thread.fpu.vxrs, 0, sizeof(current->thread.fpu.vxrs));
> 
> So I checked with a userspace that sets f8(call-saved) to 0x123 during this ioctl.
> f8 is 0 afterwards. The guest f8 is also correct, just because QEMU does clear out
> its copy of the fprs and syncs that back via synv regs.
> 
> So this must be
> 
> 	/* we have not synced the registers from kvm_run to the thread
> 	   structure. We must clear out kvm_run*/
> 	memset(&regs->vrs, 0, sizeof(regs->vrs));

Great, thanks!
Meanwhile I had a look at the missing pieces and the guarded storage resets.

> 
> 
>> +	memset(&regs->acrs, 0, sizeof(regs->acrs));
>> +
>> +	regs->etoken = 0;
>> +	regs->etoken_extension = 0;
>> +
>> +	memset(&regs->gscb, 0, sizeof(regs->gscb));
> [....]
>

Attachment: signature.asc
Description: OpenPGP digital signature