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From: Michael Kelley <mhklinux@outlook.com>
To: Roman Kisel <romank@linux.microsoft.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
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Cc: "ssengar@microsoft.com" <ssengar@microsoft.com>,
	"sunilmut@microsoft.com" <sunilmut@microsoft.com>,
	"vdso@hexbites.dev" <vdso@hexbites.dev>
Subject: RE: [PATCH v2 4/6] arm64/hyperv: Boot in a Virtual Trust Level
Date: Wed, 15 May 2024 13:39:27 +0000	[thread overview]
Message-ID: <SN6PR02MB415778D73832B587A2758BD0D4EC2@SN6PR02MB4157.namprd02.prod.outlook.com> (raw)
In-Reply-To: <20240514224508.212318-5-romank@linux.microsoft.com>

From: Roman Kisel <romank@linux.microsoft.com> Sent: Tuesday, May 14, 2024 3:44 PM
> 
> To run in the VTL mode, Hyper-V drivers have to know what
> VTL the system boots in, and the arm64/hyperv code does not
> update the variable that stores the value.
> 
> Update the variable to enable the Hyper-V drivers to boot
> in the VTL mode and print the VTL the code runs in.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> ---
>  arch/arm64/hyperv/Makefile        |  1 +
>  arch/arm64/hyperv/hv_vtl.c        | 19 +++++++++++++++++++
>  arch/arm64/hyperv/mshyperv.c      |  6 ++++++
>  arch/arm64/include/asm/mshyperv.h |  8 ++++++++
>  arch/x86/hyperv/hv_vtl.c          |  2 +-
>  5 files changed, 35 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm64/hyperv/hv_vtl.c
> 
> diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile
> index 87c31c001da9..9701a837a6e1 100644
> --- a/arch/arm64/hyperv/Makefile
> +++ b/arch/arm64/hyperv/Makefile
> @@ -1,2 +1,3 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-y		:= hv_core.o mshyperv.o
> +obj-$(CONFIG_HYPERV_VTL_MODE)	+= hv_vtl.o
> diff --git a/arch/arm64/hyperv/hv_vtl.c b/arch/arm64/hyperv/hv_vtl.c
> new file mode 100644
> index 000000000000..9b44cc49594c
> --- /dev/null
> +++ b/arch/arm64/hyperv/hv_vtl.c
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2023, Microsoft, Inc.
> + *
> + * Author : Roman Kisel <romank@linux.microsoft.com>
> + */
> +
> +#include <asm/mshyperv.h>
> +
> +void __init hv_vtl_init_platform(void)
> +{
> +	pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
> +}
> +
> +int __init hv_vtl_early_init(void)
> +{
> +	return 0;
> +}
> +early_initcall(hv_vtl_early_init);
> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
> index 208a3bcb9686..cbde483b167a 100644
> --- a/arch/arm64/hyperv/mshyperv.c
> +++ b/arch/arm64/hyperv/mshyperv.c
> @@ -96,6 +96,12 @@ static int __init hyperv_init(void)
>  		return ret;
>  	}
> 
> +	/* Find the VTL */
> +	ms_hyperv.vtl = get_vtl();
> +	if (ms_hyperv.vtl > 0) /* non default VTL */
> +		hv_vtl_early_init();

Since hv_vtl_early_init() doesn't do anything on arm64, is the above
and the empty implementation of hv_vtl_early_init() really needed?
I thought maybe a subsequent patch in this series would populate
hv_vtl_early_init() to do something, but I didn't see such.  I realize
the functions hv_vtl_init_platform() and hv_vtl_early_init() parallel
equivalent functions on x86, but I'd say drop hv_vtl_early_init() on
arm64 if it isn't needed.

Note too that the naming on the x86 side is arguably a bit messed
up. hv_vtl_init_platform() runs *before* hv_vtl_early_init().  But
typically in the Linux kernel, functions with "early init" in the name
run very early in boot, and that's not the case here.  hv_vtl_init_platform()
is actually the function that runs very early in boot, but its name is
set up to parallel ms_hyperv_init_platform(), which calls it.  On the
x86 side, I'd would argue for renaming hv_vtl_init_platform() to
hv_vtl_early_init(), and then hv_vtl_early_init() becomes hv_vtl_init().
But that's probably a separate patch.  Here on arm64, perhaps all
you need is hv_vtl_init().

Michael

> +
> +	hv_vtl_init_platform();
>  	ms_hyperv_late_init();
> 
>  	hyperv_initialized = true;
> diff --git a/arch/arm64/include/asm/mshyperv.h
> b/arch/arm64/include/asm/mshyperv.h
> index a975e1a689dd..4a8ff6be389c 100644
> --- a/arch/arm64/include/asm/mshyperv.h
> +++ b/arch/arm64/include/asm/mshyperv.h
> @@ -49,6 +49,14 @@ static inline u64 hv_get_msr(unsigned int reg)
>  				ARM_SMCCC_OWNER_VENDOR_HYP,	\
>  				HV_SMCCC_FUNC_NUMBER)
> 
> +#ifdef CONFIG_HYPERV_VTL_MODE
> +void __init hv_vtl_init_platform(void);
> +int __init hv_vtl_early_init(void);
> +#else
> +static inline void __init hv_vtl_init_platform(void) {}
> +static inline int __init hv_vtl_early_init(void) { return 0; }
> +#endif
> +
>  #include <asm-generic/mshyperv.h>
> 
>  #endif
> diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
> index 92bd5a55f093..ae3105375a12 100644
> --- a/arch/x86/hyperv/hv_vtl.c
> +++ b/arch/x86/hyperv/hv_vtl.c
> @@ -19,7 +19,7 @@ static struct real_mode_header hv_vtl_real_mode_header;
> 
>  void __init hv_vtl_init_platform(void)
>  {
> -	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
> +	pr_info("Linux runs in Hyper-V Virtual Trust Level %d\n", ms_hyperv.vtl);
> 
>  	x86_platform.realmode_reserve = x86_init_noop;
>  	x86_platform.realmode_init = x86_init_noop;
> --
> 2.45.0
> 


  reply	other threads:[~2024-05-15 13:39 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-14 22:43 [PATCH v2 0/6] arm64/hyperv: Support Virtual Trust Level Boot Roman Kisel
2024-05-14 22:43 ` [PATCH v2 1/6] arm64/hyperv: Support DeviceTree Roman Kisel
2024-05-15  7:45   ` Krzysztof Kozlowski
2024-05-15 17:33     ` Roman Kisel
2024-05-20  6:45       ` Krzysztof Kozlowski
2024-05-20 20:36         ` Roman Kisel
2024-05-15 22:02   ` Elliot Berman
2024-05-16 15:27     ` Roman Kisel
2024-05-14 22:43 ` [PATCH v2 2/6] drivers/hv: Enable VTL mode for arm64 Roman Kisel
2024-05-15 13:37   ` Michael Kelley
2024-05-15 18:04     ` Roman Kisel
2024-05-14 22:43 ` [PATCH v2 3/6] drivers/hv: arch-neutral implementation of get_vtl() Roman Kisel
2024-05-15 13:38   ` Michael Kelley
2024-05-15 18:11     ` Roman Kisel
2024-05-14 22:43 ` [PATCH v2 4/6] arm64/hyperv: Boot in a Virtual Trust Level Roman Kisel
2024-05-15 13:39   ` Michael Kelley [this message]
2024-05-15 18:13     ` Roman Kisel
2024-05-14 22:43 ` [PATCH v2 5/6] drivers/hv/vmbus: Get the irq number from DeviceTree Roman Kisel
2024-05-15  7:47   ` Krzysztof Kozlowski
2024-05-15 17:05     ` Roman Kisel
2024-05-15  9:42   ` Saurabh Singh Sengar
2024-05-15 16:31     ` Roman Kisel
2024-05-15 13:44   ` Michael Kelley
2024-05-15 18:21     ` Roman Kisel
2024-05-16  2:40   ` kernel test robot
2024-05-17 17:14   ` Rob Herring
2024-05-20 19:25     ` Roman Kisel
2024-05-14 22:43 ` [PATCH v2 6/6] drivers/pci/hyperv/arm64: vPCI MSI IRQ domain from DT Roman Kisel
2024-05-15  9:48   ` Saurabh Singh Sengar
2024-05-15 16:34     ` Roman Kisel
2024-05-15 18:12       ` Bjorn Helgaas
2024-05-15 18:34         ` Roman Kisel
2024-05-15 13:47   ` Michael Kelley
2024-05-15 18:31     ` Roman Kisel

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