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Subject: Re: [PATCH 0/5] iommu/amd: fixes for suspend/resume
From:   Maxim Levitsky <mlevitsk@redhat.com>
To:     Mike Lothian <mike@fireburn.co.uk>
Cc:     dwmw@amazon.co.uk, iommu@lists.linux-foundation.org,
        joro@8bytes.org, linux-kernel@vger.kernel.org,
        suravee.suthikulpanit@amd.com, tglx@linutronix.de, will@kernel.org
Date:   Wed, 26 Jan 2022 12:12:44 +0200
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         <20220125150832.1570-1-mike@fireburn.co.uk>
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On Wed, 2022-01-26 at 09:54 +0000, Mike Lothian wrote:
> On Wed, 26 Jan 2022 at 07:34, Maxim Levitsky <mlevitsk@redhat.com> wrote:
> > Could you post the whole dmesg, or at least:
> > 
> > dmesg | grep AMD-Vi
> > 
> > 
> > What CPU does your system have?
> > 
> > I suspect that your system doesn't GA log feature enabled in the IOMMU, and the code never checks
> > for that, and here it fails enabling it, which  before my patches was just
> > ignoring it silently.
> > 
> > 
> > Best regards,
> >         Maxim Levitsky
> > > Hope that helps
> > > 
> > > Mike
> > > 
> 
> Hi
> 
> It's an AMD Ryzen 9 5900HX
> 
> [    0.186350] AMD-Vi: ivrs, add hid:AMDI0020, uid:\_SB.FUR0, rdevid:160
> [    0.186353] AMD-Vi: ivrs, add hid:AMDI0020, uid:\_SB.FUR1, rdevid:160
> [    0.186354] AMD-Vi: ivrs, add hid:AMDI0020, uid:\_SB.FUR2, rdevid:160
> [    0.186355] AMD-Vi: ivrs, add hid:AMDI0020, uid:\_SB.FUR3, rdevid:160
> [    0.355628] pci 0000:00:00.2: AMD-Vi: IOMMU performance counters supported
> [    0.356134] pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40
> [    0.356136] AMD-Vi: Extended features (0x206d73ef22254ade): PPR
> X2APIC NX GT IA GA PC GA_vAPIC
> [    0.356140] AMD-Vi: Interrupt remapping enabled
> [    0.356141] AMD-Vi: Virtual APIC enabled
> [    0.356142] AMD-Vi: X2APIC enabled
> [    0.431377] AMD-Vi: AMD IOMMUv2 loaded and initialized
> 
> I've attached the dmesg, I notice that some boots it doesn't happen
> 
> Cheers
> 
> Mike

Great, your system does seem to support GA log 
(but a patch to check if, other that assume blindly that it is supported is 
something that should be done).

So could you bump the LOOP_TIMEOUT like by 10x or so and see if the problem goes away?

(that code should be rewritten to time based wait and not just blindly loop like that,
I also can prepare a patch for that as well).

Best regards,
	Maxim Levitsky