Re: [PATCH v4 2/6] KVM: arm64: vgic-v3: Consolidate MAINT_IRQ handling

[Oliver Upton <oliver.upton@linux.dev>]

On Mon, Jul 14, 2025 at 02:52:37PM +0200, Eric Auger wrote:
> On 7/9/25 11:14 PM, Oliver Upton wrote:
> > @@ -630,8 +608,24 @@ static int vgic_v3_set_attr(struct kvm_device *dev,
> >  	case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:
> >  	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
> >  	case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO:
> > -	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ:
> >  		return vgic_v3_attr_regs_access(dev, attr, true);
> > +	case KVM_DEV_ARM_VGIC_GRP_MAINT_IRQ: {
> > +		u32 __user *uaddr = (u32 __user *)attr->addr;
> > +		u32 val;
> > +
> > +		if (get_user(val, uaddr))
> > +			return -EFAULT;
> > +
> > +		guard(mutex)(&dev->kvm->arch.config_lock);
> Previously we had a more elaborate lock sequence in
> vgic_v3_attr_regs_access() including
> kvm_trylock_all_vcpus(dev->kvm) and mutex_lock(&dev->kvm->arch.config_lock);
> Maybe worth to document in the commit msg why it is safe to remove that?
> 

Can do, just adding FTR here that kvm_vgic_vcpu_nv_init() only takes the
config_lock so the rest is unneeded.

> 
> > +		if (vgic_initialized(dev->kvm))
> > +			return -EBUSY;
> > +
> > +		if ((val < VGIC_NR_SGIS) || (val >= VGIC_NR_PRIVATE_IRQS))
> nit: !irq_is_ppi()?

Much nicer.

Thanks,
Oliver