linux-kernel - Re: [PATCH] iommu/amd: Fix iommu remap panic while amd

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Date:   Tue, 16 Mar 2021 21:36:02 +0800
From:   Huang Rui <ray.huang@....com>
To:     Joerg Roedel <jroedel@...e.de>
Cc:     "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH] iommu/amd: Fix iommu remap panic while amd_iommu is set
 to disable

On Tue, Mar 16, 2021 at 09:16:34PM +0800, Joerg Roedel wrote:
> Hi Huang,
> 
> On Thu, Mar 11, 2021 at 10:28:07PM +0800, Huang Rui wrote:
> > diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> > index f0adbc48fd17..a08e885403b7 100644
> > --- a/drivers/iommu/amd/iommu.c
> > +++ b/drivers/iommu/amd/iommu.c
> > @@ -3862,7 +3862,7 @@ static int irq_remapping_select(struct irq_domain *d, struct irq_fwspec *fwspec,
> >  	else if (x86_fwspec_is_hpet(fwspec))
> >  		devid = get_hpet_devid(fwspec->param[0]);
> >  
> > -	if (devid < 0)
> > +	if (devid < 0 || !amd_iommu_rlookup_table)
> >  		return 0;
> 
> The problem is deeper than this fix suggests. I prepared other fixes for
> this particular problem. Please find them here:
> 

Thanks for the comments. Could you please elaborate this?

Do you mean while amd_iommu=off, we won't prepare the IVRS, and even
needn't get all ACPI talbes. Because they are never be used and the next
state will always goes into IOMMU_CMDLINE_DISABLED, am I right?

Thanks,
Ray

> 	https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fjoro%2Flinux.git%2Flog%2F%3Fh%3Diommu-fixes&amp;data=04%7C01%7Cray.huang%40amd.com%7Cce731dda3b444ac9a14108d8e87dbb3e%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637514974013915073%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=NVahf1tIfgno%2BNWPu8hY4DygiGWdKXBJ8G6OsD%2BHC14%3D&amp;reserved=0
> 
> Regards,
> 
> 	Joerg