linux-kernel - Re: [PATCH 2/3] HYPERV/IOMMU: Add Hyper-V stub IOMMU driver

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Date:   Sat, 2 Feb 2019 10:51:23 +0800
From:   Tianyu Lan <lantianyu1986@...il.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Lan Tianyu <Tianyu.Lan@...rosoft.com>, mchehab+samsung@...nel.org,
        davem@...emloft.net,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        akpm@...ux-foundation.org, nicolas.ferre@...rochip.com,
        Arnd Bergmann <arnd@...db.de>,
        "linux-kernel@...r kernel org" <linux-kernel@...r.kernel.org>,
        iommu@...ts.linux-foundation.org, michael.h.kelley@...rosoft.com,
        kys@...rosoft.com, Vitaly Kuznetsov <vkuznets@...hat.com>,
        Alex Williamson <alex.williamson@...hat.com>
Subject: Re: [PATCH 2/3] HYPERV/IOMMU: Add Hyper-V stub IOMMU driver

Hi Joerg:
             Thanks for your review.

On Sat, Feb 2, 2019 at 12:34 AM Joerg Roedel <joro@...tes.org> wrote:
>
> Hi,
>
> On Thu, Jan 31, 2019 at 06:17:32PM +0800, lantianyu1986@...il.com wrote:
> > +config HYPERV_IOMMU
> > +     bool "Hyper-V stub IOMMU support"
>
> This is not a real IOMMU driver, it only implements IRQ remapping
> capabilities. Please change the name to reflect that, e.g. to
> "Hyper-V IRQ Remapping Support" or something like that.

Yes, that makes sense. Will update.

>
> > +static int __init hyperv_prepare_irq_remapping(void)
> > +{
> > +     struct fwnode_handle *fn;
> > +     u32 apic_id;
> > +     int i;
> > +
> > +     if (x86_hyper_type != X86_HYPER_MS_HYPERV ||
> > +         !x2apic_supported())
> > +             return -ENODEV;
> > +
> > +     fn = irq_domain_alloc_named_id_fwnode("HYPERV-IR", 0);
> > +     if (!fn)
> > +             return -EFAULT;
>
> Why does this return -EFAULT? I guess there is no fault happening in
> irq_domain_alloc_named_id_fwnode()...

Yes, “-ENOMEM” should be more accurate.

-- 
Best regards
Tianyu Lan