linux-kernel - Re: [PATCH 1/3] x86/Hyper-V: Fix definition of struct hv_vp_assist

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Date:   Fri, 09 Aug 2019 12:25:14 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     lantianyu1986@...il.com
Cc:     Tianyu Lan <Tianyu.Lan@...rosoft.com>, kvm@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org, pbonzini@...hat.com,
        rkrcmar@...hat.com, corbet@....net, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, sashal@...nel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        x86@...nel.org, michael.h.kelley@...rosoft.com
Subject: Re: [PATCH 1/3] x86/Hyper-V: Fix definition of struct hv_vp_assist_page

lantianyu1986@...il.com writes:

> From: Tianyu Lan <Tianyu.Lan@...rosoft.com>
>
> The struct hv_vp_assist_page was defined incorrectly.
> The "vtl_control" should be u64[3], "nested_enlightenments_control"
> should be a u64 and there is 7 reserved bytes following "enlighten_vmentry".
> This patch is to fix it.
>
> Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
> ---
>  arch/x86/include/asm/hyperv-tlfs.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index af78cd72b8f3..a79703c56ebe 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -517,11 +517,11 @@ struct hv_timer_message_payload {
>  /* Define virtual processor assist page structure. */
>  struct hv_vp_assist_page {
>  	__u32 apic_assist;
> -	__u32 reserved;
> -	__u64 vtl_control[2];
> +	__u32 reserved1;
> +	__u64 vtl_control[3];
>  	__u64 nested_enlightenments_control[2];

In PATCH3 you define 'struct hv_nested_enlightenments_control' and it is
64bit long, not 128. We should change it here too as ...

> -	__u32 enlighten_vmentry;

enlighten_vmentry filed will get a very different offset breaking
Enlightened VMCS.

> -	__u32 padding;
> +	__u8 enlighten_vmentry;
> +	__u8 reserved2[7];
>  	__u64 current_nested_vmcs;
>  } __packed;

-- 
Vitaly