Subject: Re: [PATCH rc v1 3/4] iommu/arm-smmu-v3: Retain SMMUEN during kdump device reset

From: Nicolin Chen <[email-masked]>
Date: Tue, 14 Apr 2026 08:16:01 -0700

On Fri, Apr 10, 2026 at 06:21:43AM +0000, Tian, Kevin wrote:
> > From: Nicolin Chen <[email-masked]>
> > Sent: Friday, April 10, 2026 3:47 AM
> > 
> >  	/* Clear CR0 and sync (disables SMMU and queue processing) */
> >  	reg = readl_relaxed(smmu->base + ARM_SMMU_CR0);
> >  	if (reg & CR0_SMMUEN) {
> >  		dev_warn(smmu->dev, "SMMU currently enabled!
> > Resetting...\n");
> 
> move to after the check of kdump kernel
> 
> > @@ -5038,6 +5064,11 @@ static int arm_smmu_device_reset(struct
> > arm_smmu_device *smmu)
> >  		return ret;
> >  	}
> > 
> > +	/*
> > +	 * Disable EVTQ and PRIQ in kdump kernel. The old kernel's CDs and
> > page
> > +	 * tables may be corrupted, which could trigger event spamming.
> > PRIQ is
> > +	 * also useless since we cannot service page requests during kdump.
> > +	 */
> >  	if (is_kdump_kernel())
> >  		enables &= ~(CR0_EVTQEN | CR0_PRIQEN);
> > 
> 
> then just don't enable them in earlier lines?

I will incorporate these (and the other comments) into v2.

Thanks!
Nicolin