linux-kernel - Re: [PATCH v8 13/13] iommu/amd: Disable iommu only if amd

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Date:   Fri, 28 Jul 2017 17:08:34 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Joerg Roedel <jroedel@...e.de>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        root <root@...-dinar-02.lab.bos.redhat.com>
Subject: Re: [PATCH v8 13/13] iommu/amd: Disable iommu only if amd_iommu=off
 is specified

On 07/27/17 at 05:58pm, Joerg Roedel wrote:
> On Fri, Jul 21, 2017 at 04:59:11PM +0800, Baoquan He wrote:
> > From: root <root@...-dinar-02.lab.bos.redhat.com>
> 
> You probaly need to reset the author on this one.

Oops, sorry. I made this patch on a testing machine. Will correct it.

Thanks a lot for all these comments and great suggestions.

> 
> > 
> > It's ok to disable iommu in normal kernel. While there's no need
> > to disable it in kdump kernel after the on-flight dma issue has
> > heen fixed.
> > 
> > Signed-off-by: Baoquan He <bhe@...hat.com>
> > ---
> >  drivers/iommu/amd_iommu_init.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
> > index 8b4bac978062..880f693c809b 100644
> > --- a/drivers/iommu/amd_iommu_init.c
> > +++ b/drivers/iommu/amd_iommu_init.c
> > @@ -2494,7 +2494,8 @@ static int __init early_amd_iommu_init(void)
> >  		goto out;
> >  
> >  	/* Disable any previously enabled IOMMUs */
> > -	disable_iommus();
> > +	if (amd_iommu_disabled)
> > +		disable_iommus();
> >  
> >  	if (amd_iommu_irq_remap)
> >  		amd_iommu_irq_remap = check_ioapic_information();
> > -- 
> > 2.5.5