Re: [Xen-devel] [PATCH v6 05/11] x86/hyperv: setup hypercall page

[Jan Beulich <jbeulich@xxxxxxxx>]

On 31.01.2020 18:49, Wei Liu wrote:
> +static void __init setup_hypercall_page(void)
> +{
> +    union hv_x64_msr_hypercall_contents hypercall_msr;
> +    union hv_guest_os_id guest_id;
> +    unsigned long mfn;
> +
> +    BUILD_BUG_ON(HV_HYP_PAGE_SHIFT != PAGE_SHIFT);
> +
> +    rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id.raw);
> +    if ( !guest_id.raw )
> +    {
> +        guest_id.raw = generate_guest_id();
> +        wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id.raw);
> +    }
> +
> +    rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> +    if ( !hypercall_msr.enable )
> +    {
> +        mfn = HV_HCALL_MFN;
> +        hypercall_msr.enable = 1;
> +        hypercall_msr.guest_physical_address = mfn;
> +        wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> +    } else {
> +        mfn = hypercall_msr.guest_physical_address;
> +    }

Nit: Style. Preferably omit the braces from "else" altogether.

Jan


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