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

Nicolin Chen
2026-04-14T15:16:27Z

On Fri, Apr 10, 2026 at 06:21:43AM +0000, Tian, Kevin wrote:
> > From: Nicolin Chen <nicolinc@nvidia.com>
> > 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