Re: [PATCH v3 4/7] KVM: SVM: hyper-v: Nested enlightenments in VMCB

[Vineeth Pillai]

Hi Tom,


> >   
> > +
> > +#if IS_ENABLED(CONFIG_HYPERV)
> > +struct __packed hv_enlightenments {
> > +	struct __packed hv_enlightenments_control {
> > +		u32 nested_flush_hypercall:1;
> > +		u32 msr_bitmap:1;
> > +		u32 enlightened_npt_tlb: 1;
> > +		u32 reserved:29;
> > +	} hv_enlightenments_control;
> > +	u32 hv_vp_id;
> > +	u64 hv_vm_id;
> > +	u64 partition_assist_page;
> > +	u64 reserved;
> > +};
> > +#define VMCB_CONTROL_END	992	// 32 bytes for Hyper-V
> > +#else
> > +#define VMCB_CONTROL_END	1024
> > +#endif
> > +
> >   struct vmcb {
> >   	struct vmcb_control_area control;
> > -	u8 reserved_control[1024 - sizeof(struct vmcb_control_area)];
> > +	u8 reserved_control[VMCB_CONTROL_END - sizeof(struct vmcb_control_area)];
> > +#if IS_ENABLED(CONFIG_HYPERV)
> > +	struct hv_enlightenments hv_enlightenments;
> > +#endif
> I believe the 32 bytes at the end of the VMCB control area will be for use
> by any software/hypervisor. The APM update that documents this change,
> along with clean bit 31, isn't public, yet, but should be in a month or so
> (from what I was told).
>
> So these fields should be added generically and then your code should make
> use of the generic field mapped with your structure.
>
> To my knowledge (until the APM is public and documents everything), I
> believe the following will be in place:
>
>    VMCB offset 0x3e0 - 0x3ff is reserved for software
>    Clean bit 31 is reserved for software
>    SVM intercept exit code 0xf0000000 is reserved for software

Thanks for the details. I shall modify the code to accommodate this.


>   
> +#if IS_ENABLED(CONFIG_HYPERV)
> +	if (hypervisor_is_type(X86_HYPER_MS_HYPERV))
> +		vmcb_all_clean_mask |= BIT(VMCB_HV_NESTED_ENLIGHTENMENTS);
> +#endif
> +
> Is there any way to hide all the #if's in this and the other patches so
> that the .c files are littered with the #if IS_ENABLED() lines. Put them
> in svm.h or a new svm-hv.h file?

Will do.


> >   			  */
> >   	VMCB_DIRTY_MAX,
> > +#if IS_ENABLED(CONFIG_HYPERV)
> > +	VMCB_HV_NESTED_ENLIGHTENMENTS = 31,
> > +#endif
> Again, this should be generic.
Will do.

Thanks,
Vineeth