From: Bjorn Helgaas <helgaas@kernel.org>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Wei Liu" <wei.liu@kernel.org>,
"Sunil Muthuswamy" <sunilmut@linux.microsoft.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Dexuan Cui" <decui@microsoft.com>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] PCI: hv: Avoid the retarget interrupt hypercall in irq_unmask() on ARM64
Date: Wed, 9 Feb 2022 10:12:20 -0600 [thread overview]
Message-ID: <20220209161220.GA559499@bhelgaas> (raw)
In-Reply-To: <20220209023722.2866009-1-boqun.feng@gmail.com>
On Wed, Feb 09, 2022 at 10:37:20AM +0800, Boqun Feng wrote:
> On ARM64 Hyper-V guests, SPIs are used for the interrupts of virtual PCI
> devices, and SPIs can be managed directly via GICD registers. Therefore
> the retarget interrupt hypercall is not needed on ARM64.
>
> The retarget interrupt hypercall related code is now put in a helper
> function and only called on x86.
>
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> ---
> drivers/pci/controller/pci-hyperv.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 20ea2ee330b8..80aa33ef5bf0 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -1457,7 +1457,7 @@ static void hv_irq_mask(struct irq_data *data)
> }
>
> /**
> - * hv_irq_unmask() - "Unmask" the IRQ by setting its current
> + * __hv_irq_unmask() - "Unmask" the IRQ by setting its current
> * affinity.
> * @data: Describes the IRQ
> *
> @@ -1466,7 +1466,7 @@ static void hv_irq_mask(struct irq_data *data)
> * is built out of this PCI bus's instance GUID and the function
> * number of the device.
> */
> -static void hv_irq_unmask(struct irq_data *data)
> +static void __hv_irq_unmask(struct irq_data *data)
> {
> struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
> struct hv_retarget_device_interrupt *params;
> @@ -1569,6 +1569,13 @@ static void hv_irq_unmask(struct irq_data *data)
> if (!hv_result_success(res) && hbus->state != hv_pcibus_removing)
> dev_err(&hbus->hdev->device,
> "%s() failed: %#llx", __func__, res);
> +}
> +
> +static void hv_irq_unmask(struct irq_data *data)
> +{
> + /* Only use a hypercall on x86 */
This comment isn't useful because it only repeats what we can already
see from the "IS_ENABLED(CONFIG_X86)" below and it doesn't say
anything about *why*.
Didn't we just go though an exercise of adding interfaces for
arch-specific things, i.e., 831c1ae725f7 ("PCI: hv: Make the code arch
neutral by adding arch specific interfaces")? Maybe this should be
another such interface?
If you add Hyper-V support for a third arch, this #ifdef will likely
be silently incorrect. If you add an interface, there's at least a
clue that this needs to be evaluated.
> + if (IS_ENABLED(CONFIG_X86))
> + __hv_irq_unmask(data);
>
> if (data->parent_data->chip->irq_unmask)
> irq_chip_unmask_parent(data);
> --
> 2.35.1
>
next prev parent reply other threads:[~2022-02-09 16:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 2:37 [RFC PATCH] PCI: hv: Avoid the retarget interrupt hypercall in irq_unmask() on ARM64 Boqun Feng
2022-02-09 16:12 ` Bjorn Helgaas [this message]
2022-02-10 0:31 ` Boqun Feng
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