Re: [RFC PATCH V3 03/11] x86/Hyper-V: Add new hvcall guest address host visibility support

[Tianyu Lan <ltykernel@xxxxxxxxx>]

Hi Vitaly:
        Thanks for your review.

On 6/10/2021 5:47 PM, Vitaly Kuznetsov wrote:
> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h 
> > b/arch/x86/include/asm/hyperv-tlfs.h
> > index 606f5cc579b2..632281b91b44 100644
> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> > @@ -262,6 +262,17 @@ enum hv_isolation_type {
> >   #define HV_X64_MSR_TIME_REF_COUNT     HV_REGISTER_TIME_REF_COUNT
> >   #define HV_X64_MSR_REFERENCE_TSC      HV_REGISTER_REFERENCE_TSC
> >   
> > +/* Hyper-V GPA map flags */
> > +#define HV_MAP_GPA_PERMISSIONS_NONE            0x0
> > +#define HV_MAP_GPA_READABLE                    0x1
> > +#define HV_MAP_GPA_WRITABLE                    0x2
> > +
> > +enum vmbus_page_visibility {
> > +       VMBUS_PAGE_NOT_VISIBLE = 0,
> > +       VMBUS_PAGE_VISIBLE_READ_ONLY = 1,
> > +       VMBUS_PAGE_VISIBLE_READ_WRITE = 3
> > +};
> > +
> Why do we need both flags and the enum? I don't see HV_MAP_GPA_* being
> used anywhere and VMBUS_PAGE_VISIBLE_READ_WRITE looks like
> HV_MAP_GPA_READABLE | HV_MAP_GPA_WRITABLE.
>
> As this is used to communicate with the host, I'd suggest to avoid using
> enum and just use flags everywhere.
Nice catch. Will update in the next version.

Thanks.