From: Anirudh Rayabharam <anrayabh@xxxxxxxxxxxxxxxxxxx> Sent: Friday, November 4, 2022 12:17 AM
>
> On Thu, Nov 03, 2022 at 09:56:54PM -0700, Saurabh Sengar wrote:
> > The struct hv_vp_assist_page has 24 bytes which is defined as u64[3],
> > expand that to expose vtl_entry_reason, vtl_ret_x64rax and vtl_ret_x64rcx
> > field. vtl_entry_reason is updated by hypervisor for the entry reason as
> > to why the VTL was entered on the virtual processor.
> > Guest updates the vtl_ret_* fields to provide the register values to
> > restore on VTL return. The specific register values that are restored
> > which will be updated on vtl_ret_x64rax and vtl_ret_x64rcx.
> > Also added the missing fields for synthetic_time_unhalted_timer_expired,
> > virtualization_fault_information and intercept_message.
> >
> > Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> > ---
> > arch/x86/include/asm/hyperv-tlfs.h | 11 ++++++++++-
> > 1 file changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-
> tlfs.h
> > index f769b9db4630..b3d0f42853d2 100644
> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> > @@ -377,11 +377,20 @@ struct hv_nested_enlightenments_control {
> > struct hv_vp_assist_page {
> > __u32 apic_assist;
> > __u32 reserved1;
> > - __u64 vtl_control[3];
> > + __u8 vtl_entry_reason;
>
> This is defined as an enum in the TLFS [1]. We should do the same.
> And since the TLFS defines it as an enum it is a 32 bit value and
> not a u8.
In the *tlfs.h files we have avoided defining fields with type "enum"
because of the potential for variability in number of bytes it occupies.
The TLFS documentation assumes an enum is 4 bytes, so in these
structure definitions we use a __u32 type to be explicit about the size.
We do have enum types defined in the *tlfs.h files, but these are just
lists of related constant values, and that's OK.
Michael
>
> > + __u8 vtl_reserved[7];
> > + __u64 vtl_ret_x64rax;
> > + __u64 vtl_ret_x64rcx;
>
> The TLFS groups the above VTL related fields into a struct
> HV_VP_VTL_CONTROL. Any reason to not do the same?
>
> [1] https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/datatypes/hv_vp_vtl_control
>
> Thanks,
> Anirudh.
>
> > struct hv_nested_enlightenments_control nested_control;
> > __u8 enlighten_vmentry;
> > __u8 reserved2[7];
> > __u64 current_nested_vmcs;
> > + __u8 synthetic_time_unhalted_timer_expired;
> > + __u8 reserved3[7];
> > + __u8 virtualization_fault_information[40];
> > + __u8 reserved4[8];
> > + __u8 intercept_message[256];
> > + __u8 vtl_ret_actions[256];
> > } __packed;
> >
> > struct hv_enlightened_vmcs {
> > --
> > 2.34.1
