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Date: Wed, 15 May 2024 09:45:49 +0200
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Subject: Re: [PATCH v2 1/6] arm64/hyperv: Support DeviceTree
To: Roman Kisel <romank@linux.microsoft.com>, arnd@arndb.de,
 bhelgaas@google.com, bp@alien8.de, catalin.marinas@arm.com,
 dave.hansen@linux.intel.com, decui@microsoft.com, haiyangz@microsoft.com,
 hpa@zytor.com, kw@linux.com, kys@microsoft.com, lenb@kernel.org,
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 rafael@kernel.org, robh@kernel.org, tglx@linutronix.de, wei.liu@kernel.org,
 will@kernel.org, linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
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 linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org
Cc: ssengar@microsoft.com, sunilmut@microsoft.com, vdso@hexbites.dev
References: <20240514224508.212318-1-romank@linux.microsoft.com>
 <20240514224508.212318-2-romank@linux.microsoft.com>
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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In-Reply-To: <20240514224508.212318-2-romank@linux.microsoft.com>
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On 15/05/2024 00:43, Roman Kisel wrote:
> The Virtual Trust Level platforms rely on DeviceTree, and the
> arm64/hyperv code supports ACPI only. Update the logic to
> support DeviceTree on boot as well as ACPI.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> ---
>  arch/arm64/hyperv/mshyperv.c | 34 +++++++++++++++++++++++++++++-----
>  1 file changed, 29 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
> index b1a4de4eee29..208a3bcb9686 100644
> --- a/arch/arm64/hyperv/mshyperv.c
> +++ b/arch/arm64/hyperv/mshyperv.c
> @@ -15,6 +15,9 @@
>  #include <linux/errno.h>
>  #include <linux/version.h>
>  #include <linux/cpuhotplug.h>
> +#include <linux/libfdt.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
>  #include <asm/mshyperv.h>
>  
>  static bool hyperv_initialized;
> @@ -27,6 +30,29 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info *info)
>  	return 0;
>  }
>  
> +static bool hyperv_detect_fdt(void)
> +{
> +#ifdef CONFIG_OF
> +	const unsigned long hyp_node = of_get_flat_dt_subnode_by_name(
> +			of_get_flat_dt_root(), "hypervisor");

Why do you add an ABI for node name? Although name looks OK, but is it
really described in the spec that you depend on it? I really do not like
name dependencies...

Where is the binding for this?

Best regards,
Krzysztof