Re: [PATCH v7 10/10] Drivers: hv: Enable Hyper-V code to be built on ARM64

From: Ben Dooks <ben.dooks@codethink.co.uk>
To: Ard Biesheuvel <ardb@kernel.org>,
	Michael Kelley <mikelley@microsoft.com>
Cc: Will Deacon <will@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-hyperv@vger.kernel.org,
	linux-efi <linux-efi@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	wei.liu@kernel.org, vkuznets <vkuznets@redhat.com>,
	KY Srinivasan <kys@microsoft.com>,
	Sunil Muthuswamy <sunilmut@microsoft.com>,
	Boqun Feng <boqun.feng@gmail.com>
Subject: Re: [PATCH v7 10/10] Drivers: hv: Enable Hyper-V code to be built on ARM64
Date: Tue, 25 Aug 2020 09:47:00 +0100	[thread overview]
Message-ID: <5e8af3c3-fe08-0a56-fe05-0527a6cae0dd@codethink.co.uk> (raw)
In-Reply-To: <CAMj1kXHKDD5+Na7t=bbkqo2OaiidmnJg+RqermV-2=exj-P77A@mail.gmail.com>

On 24/08/2020 18:24, Ard Biesheuvel wrote:
> On Mon, 24 Aug 2020 at 18:48, Michael Kelley <mikelley@microsoft.com> wrote:
>>
>> Update drivers/hv/Kconfig so CONFIG_HYPERV can be selected on
>> ARM64, causing the Hyper-V specific code to be built.
>>
>> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
>> ---
>>   drivers/hv/Kconfig | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
>> index 79e5356..1113e49 100644
>> --- a/drivers/hv/Kconfig
>> +++ b/drivers/hv/Kconfig
>> @@ -4,7 +4,8 @@ menu "Microsoft Hyper-V guest support"
>>
>>   config HYPERV
>>          tristate "Microsoft Hyper-V client drivers"
>> -       depends on X86 && ACPI && X86_LOCAL_APIC && HYPERVISOR_GUEST
>> +       depends on ACPI && \
>> +                       ((X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) || ARM64)
>>          select PARAVIRT
>>          select X86_HV_CALLBACK_VECTOR
>>          help
> 
> Given the comment in a previous patch
> 
> +/*
> + * All data structures defined in the TLFS that are shared between Hyper-V
> + * and a guest VM use Little Endian byte ordering.  This matches the default
> + * byte ordering of Linux running on ARM64, so no special handling is required.
> + */
> 
> shouldn't this depend on !CONFIG_CPU_BIG_ENDIAN ?

or mark the data __le and have the appropriate accessor functions do
the swapping.

-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

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