linux-kernel - Re: [PATCH v5 4/5] hyperv: Do not overlap the hvcall IO areas in get

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Message-ID: <04e97a7e-efee-43e2-b4f4-6df169ed51a5@linux.microsoft.com>
Date: Wed, 8 Jan 2025 09:47:55 -0800
From: Roman Kisel <romank@...ux.microsoft.com>
To: Wei Liu <wei.liu@...nel.org>
Cc: hpa@...or.com, kys@...rosoft.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, decui@...rosoft.com,
 eahariha@...ux.microsoft.com, haiyangz@...rosoft.com, mingo@...hat.com,
 mhklinux@...look.com, nunodasneves@...ux.microsoft.com, tglx@...utronix.de,
 tiala@...rosoft.com, linux-hyperv@...r.kernel.org,
 linux-kernel@...r.kernel.org, x86@...nel.org, apais@...rosoft.com,
 benhill@...rosoft.com, ssengar@...rosoft.com, sunilmut@...rosoft.com,
 vdso@...bites.dev
Subject: Re: [PATCH v5 4/5] hyperv: Do not overlap the hvcall IO areas in
 get_vtl()



On 1/7/2025 11:36 PM, Wei Liu wrote:
> On Mon, Dec 30, 2024 at 10:09:40AM -0800, Roman Kisel wrote:
>> The Top-Level Functional Specification for Hyper-V, Section 3.6 [1, 2],
>> disallows overlapping of the input and output hypercall areas, and
>> get_vtl(void) does overlap them.
>>
>> Use the output hypercall page of the current vCPU for the hypercall.
>>
>> [1] https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/hypercall-interface
>> [2] https://github.com/MicrosoftDocs/Virtualization-Documentation/tree/main/tlfs
>>
>> Fixes: 8387ce06d70b ("x86/hyperv: Set Virtual Trust Level in VMBus init message")
>> Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>
> 
> You forgot to pick up Tianyu's Reviewed-by tag in the previous version.
> In the future please make sure to collect all the tags you get from
> previous review rounds.

Apologies, my bad! Will collect tags in the future.

> 
> Thanks,
> Wei.
> 
>> ---
>>   arch/x86/hyperv/hv_init.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
>> index f82d1aefaa8a..173005e6a95d 100644
>> --- a/arch/x86/hyperv/hv_init.c
>> +++ b/arch/x86/hyperv/hv_init.c
>> @@ -422,7 +422,7 @@ static u8 __init get_vtl(void)
>>   
>>   	local_irq_save(flags);
>>   	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
>> -	output = (struct hv_output_get_vp_registers *)input;
>> +	output = *this_cpu_ptr(hyperv_pcpu_output_arg);
>>   
>>   	memset(input, 0, struct_size(input, names, 1));
>>   	input->partition_id = HV_PARTITION_ID_SELF;
>> -- 
>> 2.34.1
>>

-- 
Thank you,
Roman