From: Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: lantianyu1986-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
Cc: sashal-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
Lan Tianyu <Tianyu.Lan-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>,
arnd-r2nGTMty4D4@public.gmane.org,
gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org,
nicolas.ferre-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
michael.h.kelley-0li6OtcxBFHby3iVrkZq2A@public.gmane.org,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
mchehab+samsung-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
vkuznets-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
kys-0li6OtcxBFHby3iVrkZq2A@public.gmane.org,
davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org,
dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org
Subject: Re: [PATCH V3 2/3] HYPERV/IOMMU: Add Hyper-V stub IOMMU driver
Date: Thu, 7 Feb 2019 11:15:14 -0700 [thread overview]
Message-ID: <20190207111514.425d137b@w520.home> (raw)
In-Reply-To: <1549553629-8414-3-git-send-email-Tianyu.Lan-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>
On Thu, 7 Feb 2019 23:33:48 +0800
lantianyu1986-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
> From: Lan Tianyu <Tianyu.Lan-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>
>
> On the bare metal, enabling X2APIC mode requires interrupt remapping
> function which helps to deliver irq to cpu with 32-bit APIC ID.
> Hyper-V doesn't provide interrupt remapping function so far and Hyper-V
> MSI protocol already supports to deliver interrupt to the CPU whose
> virtual processor index is more than 255. IO-APIC interrupt still has
> 8-bit APIC ID limitation.
>
> This patch is to add Hyper-V stub IOMMU driver in order to enable
> X2APIC mode successfully in Hyper-V Linux guest. The driver returns X2APIC
> interrupt remapping capability when X2APIC mode is available. Otherwise,
> it creates a Hyper-V irq domain to limit IO-APIC interrupts' affinity
> and make sure cpus assigned with IO-APIC interrupt have 8-bit APIC ID.
>
> Define 24 IO-APIC remapping entries because Hyper-V only expose one
> single IO-APIC and one IO-APIC has 24 pins according IO-APIC spec(
> https://pdos.csail.mit.edu/6.828/2016/readings/ia32/ioapic.pdf).
>
> Signed-off-by: Lan Tianyu <Tianyu.Lan-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>
> ---
> Change since v2:
> - Improve comment about why save IO-APIC entry in the irq chip data.
> - Some code improvement.
> - Improve statement in the IOMMU Kconfig.
>
> Change since v1:
> - Remove unused pr_fmt
> - Make ioapic_ir_domain as static variable
> - Remove unused variables cfg and entry in the hyperv_irq_remapping_alloc()
> - Fix comments
> ---
> drivers/iommu/Kconfig | 8 ++
> drivers/iommu/Makefile | 1 +
> drivers/iommu/hyperv-iommu.c | 194 ++++++++++++++++++++++++++++++++++++++++++
> drivers/iommu/irq_remapping.c | 3 +
> drivers/iommu/irq_remapping.h | 1 +
> 5 files changed, 207 insertions(+)
> create mode 100644 drivers/iommu/hyperv-iommu.c
...
> diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
> new file mode 100644
> index 0000000..d8572c5
> --- /dev/null
> +++ b/drivers/iommu/hyperv-iommu.c
...
> +static int __init hyperv_prepare_irq_remapping(void)
> +{
> + struct fwnode_handle *fn;
> + int i;
> +
> + if (!hypervisor_is_type(x86_hyper_type) ||
> + !x2apic_supported())
> + return -ENODEV;
> +
> + fn = irq_domain_alloc_named_id_fwnode("HYPERV-IR", 0);
> + if (!fn)
> + return -ENOMEM;
> +
> + ioapic_ir_domain =
> + irq_domain_create_hierarchy(arch_get_ir_parent_domain(),
> + 0, IOAPIC_REMAPPING_ENTRY, fn,
> + &hyperv_ir_domain_ops, NULL);
> +
> + irq_domain_free_fwnode(fn);
> +
> + /*
> + * 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 = 0; i < 256; i++)
> + if (cpu_physical_id(i) < 256)
> + cpumask_set_cpu(i, &ioapic_max_cpumask);
This looks sketchy. What if NR_CPUS is less than 256? Thanks,
Alex
> +
> + return 0;
> +}
next prev parent reply other threads:[~2019-02-07 18:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-07 15:33 [PATCH V3 0/3] x86/Hyper-V/IOMMU: Add Hyper-V IOMMU driver to support x2apic mode lantianyu1986
[not found] ` <1549553629-8414-1-git-send-email-Tianyu.Lan-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>
2019-02-07 15:33 ` [PATCH V3 1/3] x86/Hyper-V: Set x2apic destination mode to physical when x2apic is available lantianyu1986-Re5JQEeQqe8AvxtiuMwx3w
2019-02-10 21:48 ` Thomas Gleixner
2019-02-11 8:05 ` Tianyu Lan
2019-02-07 15:33 ` [PATCH V3 2/3] HYPERV/IOMMU: Add Hyper-V stub IOMMU driver lantianyu1986
2019-02-07 17:15 ` Vitaly Kuznetsov
2019-02-11 8:19 ` Tianyu Lan
[not found] ` <1549553629-8414-3-git-send-email-Tianyu.Lan-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>
2019-02-07 18:15 ` Alex Williamson [this message]
2019-02-11 8:10 ` Tianyu Lan
2019-02-08 14:51 ` Olaf Hering
2019-02-11 8:21 ` Tianyu Lan
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