Hi Michael:
Thanks for your review.
-----Original Message-----
From: Michael Kelley <mikel...@microsoft.com>
Sent: Friday, February 22, 2019 1:28 AM
To: lantianyu1...@gmail.com
Cc: Tianyu Lan <tianyu....@microsoft.com>; j...@8bytes.org;
mchehab+sams...@kernel.org; da...@davemloft.net; gre...@linuxfoundation.org;
nicolas.fe...@microchip.com; a...@arndb.de; linux-ker...@vger.kernel.org;
iommu@lists.linux-foundation.org; KY Srinivasan <k...@microsoft.com>; vkuznets
<vkuzn...@redhat.com>; alex.william...@redhat.com; sas...@kernel.org;
dan.carpen...@oracle.com; linux-hyp...@vger.kernel.org
Subject: RE: [PATCH V4 2/3] HYPERV/IOMMU: Add Hyper-V stub IOMMU driver
From: lantianyu1...@gmail.com <lantianyu1...@gmail.com> Sent: Monday, February
11, 2019 6:20 AM
> + /*
> + * Hyper-V doesn't provide irq remapping function for
> + * IO-APIC and so IO-APIC only accepts 8-bit APIC ID.
> + * Cpu's APIC ID is read from ACPI MADT table and APIC IDs
> + * in the MADT table on Hyper-v are sorted monotonic increasingly.
> + * APIC ID reflects cpu topology. There maybe some APIC ID
> + * gaps when cpu number in a socket is not power of two. Prepare
> + * max cpu affinity for IOAPIC irqs. Scan cpu 0-255 and set cpu
> + * into ioapic_max_cpumask if its APIC ID is less than 256.
> + */
> + for (i = min_t(unsigned int, num_possible_cpus(), 255); i >= 0; i--)
The above isn't quite right. For example, if num_possible_cpus() is 8, then
the loop will be executed 9 times, for values 8 down through 0.
It should be executed for values 7 down through 0.
Yes, fix this in the V5. Thanks.
> + if (cpu_physical_id(i) < 256)
> + cpumask_set_cpu(i, &ioapic_max_cpumask);
> +
> + return 0;
> +}
Michael
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