From: Jerry Snitselaar <jsnitsel@redhat.com>
To: Will Deacon <will@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
iommu@lists.linux-foundation.org
Subject: Re: [GIT PULL] IOMMU fix for 5.10 (-final)
Date: Wed, 09 Dec 2020 12:12:31 -0700 [thread overview]
Message-ID: <87tusulrog.fsf@redhat.com> (raw)
In-Reply-To: <20201209185020.GC8778@willie-the-truck>
Will Deacon @ 2020-12-09 11:50 MST:
> On Wed, Dec 09, 2020 at 10:07:46AM -0800, Linus Torvalds wrote:
>> On Wed, Dec 9, 2020 at 6:12 AM Will Deacon <will@kernel.org> wrote:
>> >
>> > Please pull this one-liner AMD IOMMU fix for 5.10. It's actually a fix
>> > for a fix, where the size of the interrupt remapping table was increased
>> > but a related constant for the size of the interrupt table was forgotten.
>>
>> Pulled.
>
> Thanks.
>
>> However, why didn't this then add some sanity checking for the two
>> different #defines to be in sync?
>>
>> IOW, something like
>>
>> #define AMD_IOMMU_IRQ_TABLE_SHIFT 9
>>
>> #define MAX_IRQS_PER_TABLE (1 << AMD_IOMMU_IRQ_TABLE_SHIFT)
>> #define DTE_IRQ_TABLE_LEN ((u64)AMD_IOMMU_IRQ_TABLE_SHIFT << 1)
Since the field in the device table entry format expects it to be n
where there are 2^n entries in the table I guess it should be:
#define DTE_IRQ_TABLE_LEN 9
#define MAX_IRQS_PER_TABLE (1 << DTE_IRQ_TABLE_LEN)
>>
>> or whatever. Hmm?
>
> This looks like a worthwhile change to me, but I don't have any hardware
> so I've been very reluctant to make even "obvious" driver changes here.
>
> Suravee -- please can you post a patch implementing the above?
>
>> That way this won't happen again, but perhaps equally importantly the
>> linkage will be more clear, and there won't be those random constants.
>>
>> Naming above is probably garbage - I assume there's some actual
>> architectural name for that irq table length field in the DTE?
>
> The one in the spec is even better: "IntTabLen".
>
> Will
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
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next prev parent reply other threads:[~2020-12-09 19:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 14:12 [GIT PULL] IOMMU fix for 5.10 (-final) Will Deacon
2020-12-09 18:07 ` Linus Torvalds
2020-12-09 18:50 ` Will Deacon
2020-12-09 19:12 ` Jerry Snitselaar [this message]
2020-12-09 19:15 ` Jerry Snitselaar
2020-12-09 19:17 ` Linus Torvalds
2020-12-09 19:23 ` Jerry Snitselaar
2020-12-10 11:55 ` Suravee Suthikulpanit
2020-12-09 18:09 ` pr-tracker-bot
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