linux-kernel - Re: [PATCH v3 4/7] arm64: hyperv: Boot in a Virtual Trust Level

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Message-ID: <cca36d1f-a1f3-4d5c-a7ea-6c434903b9ed@linux.microsoft.com>
Date: Mon, 5 Aug 2024 07:55:59 -0700
From: Roman Kisel <romank@...ux.microsoft.com>
To: Wei Liu <wei.liu@...nel.org>
Cc: arnd@...db.de, bhelgaas@...gle.com, bp@...en8.de,
 catalin.marinas@....com, dave.hansen@...ux.intel.com, decui@...rosoft.com,
 haiyangz@...rosoft.com, hpa@...or.com, kw@...ux.com, kys@...rosoft.com,
 lenb@...nel.org, lpieralisi@...nel.org, mingo@...hat.com, rafael@...nel.org,
 robh@...nel.org, tglx@...utronix.de, will@...nel.org,
 linux-acpi@...r.kernel.org, linux-arch@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-hyperv@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, x86@...nel.org,
 apais@...rosoft.com, benhill@...rosoft.com, ssengar@...rosoft.com,
 sunilmut@...rosoft.com, vdso@...bites.dev
Subject: Re: [PATCH v3 4/7] arm64: hyperv: Boot in a Virtual Trust Level



On 8/2/2024 6:22 PM, Wei Liu wrote:
> On Fri, Jul 26, 2024 at 03:59:07PM -0700, Roman Kisel wrote:
>> 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@...ux.microsoft.com>
>> ---
>>   arch/arm64/hyperv/Makefile        |  1 +
>>   arch/arm64/hyperv/hv_vtl.c        | 13 +++++++++++++
>>   arch/arm64/hyperv/mshyperv.c      |  4 ++++
>>   arch/arm64/include/asm/mshyperv.h |  7 +++++++
>>   4 files changed, 25 insertions(+)
>>   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..38642b7b6be0
>> --- /dev/null
>> +++ b/arch/arm64/hyperv/hv_vtl.c
>> @@ -0,0 +1,13 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2024, Microsoft, Inc.
>> + *
>> + * Author : Roman Kisel <romank@...ux.microsoft.com>
>> + */
>> +
>> +#include <asm/mshyperv.h>
>> +
>> +void __init hv_vtl_init_platform(void)
>> +{
>> +	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
>> +}
>> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
>> index 341f98312667..8fd04d6e4800 100644
>> --- a/arch/arm64/hyperv/mshyperv.c
>> +++ b/arch/arm64/hyperv/mshyperv.c
>> @@ -98,6 +98,10 @@ static int __init hyperv_init(void)
>>   		return ret;
>>   	}
>>   
>> +	/* Find the VTL */
>> +	ms_hyperv.vtl = get_vtl();
>> +	hv_vtl_init_platform();
> 
> It doesn't make sense to me because this function unconditionally prints
> Linux runs in Hyper-V Virtual Trust Level.
> 
Thought to structure this as the similar parts of the VTL support are. 
Will remove, thank you!

> Thanks,
> Wei.
> 
>> +
>>   	ms_hyperv_late_init();
>>   
>>   	hyperv_initialized = true;
>> diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
>> index a7a3586f7cb1..63d6bb6998fc 100644
>> --- a/arch/arm64/include/asm/mshyperv.h
>> +++ b/arch/arm64/include/asm/mshyperv.h
>> @@ -49,6 +49,13 @@ 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) {}
>> +#endif
>> +
>>   #include <asm-generic/mshyperv.h>
>>   
>>   #define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_0	0x7948734d
>> -- 
>> 2.34.1
>>

-- 
Thank you,
Roman