Re: [PATCH V4 02/13] x86/hyperv: Initialize shared memory boundary in the Isolation VM.

[Tianyu Lan]

Hi Michael:
      Thanks for your review.

On 9/2/2021 8:15 AM, Michael Kelley wrote:
> From: Tianyu Lan <ltykernel@xxxxxxxxx> Sent: Friday, August 27, 2021 10:21 AM
> > Hyper-V exposes shared memory boundary via cpuid
> > HYPERV_CPUID_ISOLATION_CONFIG and store it in the
> > shared_gpa_boundary of ms_hyperv struct. This prepares
> > to share memory with host for SNP guest.
> >
> > Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
> > ---
> > Change since v3:
> > 	* user BIT_ULL to get shared_gpa_boundary
> > 	* Rename field Reserved* to reserved
> > ---
> >   arch/x86/kernel/cpu/mshyperv.c |  2 ++
> >   include/asm-generic/mshyperv.h | 12 +++++++++++-
> >   2 files changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> > index 20557a9d6e25..8bb001198316 100644
> > --- a/arch/x86/kernel/cpu/mshyperv.c
> > +++ b/arch/x86/kernel/cpu/mshyperv.c
> > @@ -313,6 +313,8 @@ static void __init ms_hyperv_init_platform(void)
> >   	if (ms_hyperv.priv_high & HV_ISOLATION) {
> >   		ms_hyperv.isolation_config_a = cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
> >   		ms_hyperv.isolation_config_b = cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);
> > +		ms_hyperv.shared_gpa_boundary =
> > +			BIT_ULL(ms_hyperv.shared_gpa_boundary_bits);
> >
> >   		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
> >   			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
> > diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> > index 0924bbd8458e..7537ae1db828 100644
> > --- a/include/asm-generic/mshyperv.h
> > +++ b/include/asm-generic/mshyperv.h
> > @@ -35,7 +35,17 @@ struct ms_hyperv_info {
> >   	u32 max_vp_index;
> >   	u32 max_lp_index;
> >   	u32 isolation_config_a;
> > -	u32 isolation_config_b;
> > +	union {
> > +		u32 isolation_config_b;
> > +		struct {
> > +			u32 cvm_type : 4;
> > +			u32 reserved11 : 1;
> > +			u32 shared_gpa_boundary_active : 1;
> > +			u32 shared_gpa_boundary_bits : 6;
> > +			u32 reserved12 : 20;
>
> I'm still curious about the "11" and "12" in the reserved
> field names.  Why not just "reserved1" and "reserved2"?
> Having the "11" and "12" isn't wrong, but it makes one
> wonder why since it's not usual. :-)

Yes, will update. Thanks.