linux-kernel - Re: [PATCH] x86/hyperv: Set pv

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Date:   Tue, 15 Oct 2019 10:39:00 +0100
From:   Wei Liu <wei.liu@...nel.org>
To:     Andrea Parri <parri.andrea@...il.com>
Cc:     Linux Kernel List <linux-kernel@...r.kernel.org>,
        Linux on Hyper-V List <linux-hyperv@...r.kernel.org>,
        x86@...nel.org, "K . Y . Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Dexuan Cui <decui@...rosoft.com>
Subject: Re: [PATCH] x86/hyperv: Set pv_info.name to "Hyper-V"

On Tue, 15 Oct 2019 at 10:30, Andrea Parri <parri.andrea@...il.com> wrote:
>
> Michael reported that the x86/hyperv initialization code printed the
> following dmesg when running in a VM on Hyper-V:
>
>   [    0.000738] Booting paravirtualized kernel on bare hardware
>
> Let the x86/hyperv initialization code set pv_info.name to "Hyper-V";
> with this addition, the dmesg read:
>
>   [    0.000138] Booting paravirtualized kernel on Hyper-V
>
> Reported-by: Michael Kelley <mikelley@...rosoft.com>
> Signed-off-by: Andrea Parri <parri.andrea@...il.com>
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 105844d542e5..c7d1801fa88b 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -154,6 +154,8 @@ static uint32_t  __init ms_hyperv_platform(void)

This function is for platform detection only.

>         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
>                 return 0;
>
> +       pv_info.name = "Hyper-V";
> +

At this point we're not sure if Linux is really running on Hyper-V yet.

Setting pv_info.name should be moved to the init_platform hook, i.e.
ms_hyperv_init_platform.

Wei.

>         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
>               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
>
> --
> 2.17.1
>