Re: [PATCH] iommu/amd: Disable guest vapic logging during early kdump init

[Suravee Suthikulpanit]

Joeg / Jerry,

On 7/22/22 9:37 PM, Joerg Roedel wrote:
> On Wed, Jul 20, 2022 at 05:34:39PM -0700, Jerry Snitselaar wrote:
> > diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> > index 1d08f87e734b..2b00d7f28df7 100644
> > --- a/drivers/iommu/amd/init.c
> > +++ b/drivers/iommu/amd/init.c
> > @@ -815,6 +815,11 @@ static void free_ga_log(struct amd_iommu *iommu)
> >   #endif
> >   }
> >   
> > +static void iommu_ga_log_disable(struct amd_iommu *iommu)
> > +{
> > +	iommu_feature_disable(iommu, CONTROL_GALOG_EN);
> > +}
> > +
> >   static int iommu_ga_log_enable(struct amd_iommu *iommu)
> >   {
> >   #ifdef CONFIG_IRQ_REMAP
> > @@ -2504,6 +2509,7 @@ static void early_enable_iommus(void)
> >   		for_each_iommu(iommu) {
> >   			iommu_disable_command_buffer(iommu);
> >   			iommu_disable_event_buffer(iommu);
> > +			iommu_ga_log_disable(iommu);
> >   			iommu_enable_command_buffer(iommu);
> >   			iommu_enable_event_buffer(iommu);
> >   			iommu_enable_ga(iommu);
>
> Looks about right, but I also let Suravee comment on this.
>
> Disabling the GA-Log under a device still using it should hopefully not
> put it into some undefined state.

Sorry for late reply. I have been actually working on the new GAM and GALOG enabling code,
which should also address this issue as well. I'll send out the patch soon.

Regards,
Suravee