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From:   "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To:     Boqun Feng <boqun.feng@gmail.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Wei Liu <wei.liu@kernel.org>
CC:     Sunil Muthuswamy <sunilmut@linux.microsoft.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Dexuan Cui <decui@microsoft.com>,
        Rob Herring <robh@kernel.org>,
        =?iso-8859-2?Q?Krzysztof_Wilczy=F1ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
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        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [RFC PATCH v2] PCI: hv: Avoid the retarget interrupt hypercall in
 irq_unmask() on ARM64
Thread-Topic: [RFC PATCH v2] PCI: hv: Avoid the retarget interrupt hypercall
 in irq_unmask() on ARM64
Thread-Index: AQHYI7D6XgWM06oOwkGkqfFHgzPdiKyX79sw
Date:   Thu, 17 Feb 2022 16:31:06 +0000
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References: <20220217034525.1687678-1-boqun.feng@gmail.com>
In-Reply-To: <20220217034525.1687678-1-boqun.feng@gmail.com>
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From: Boqun Feng <boqun.feng@gmail.com> Sent: Wednesday, February 16, 2022 =
7:45 PM
>=20
> 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.
>=20
> An arch-specific interface hv_arch_irq_unmask() is introduced to handle
> the architecture level differences on this. For x86, the behavior
> remains unchanged, while for ARM64 no hypercall is invoked when
> unmasking an irq for virtual PCI devices.
>=20
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> ---
> v1 -> v2:
>=20
> *	Introduce arch-specific interface hv_arch_irq_unmask() as
> 	suggested by Bjorn
>=20
>  drivers/pci/controller/pci-hyperv.c | 233 +++++++++++++++-------------
>  1 file changed, 122 insertions(+), 111 deletions(-)

Reviewed-by: Michael Kelley <mikelley@microsoft.com>