RE: [PATCH V3 05/13] HV: Add Write/Read MSR registers via ghcb page

[Michael Kelley]

From: Michael Kelley <mikelley@xxxxxxxxxxxxx> Sent: Friday, August 13, 2021 12:31 PM
> To: Tianyu Lan <ltykernel@xxxxxxxxx>; KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>;
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> Subject: RE: [PATCH V3 05/13] HV: Add Write/Read MSR registers via ghcb page
> 
> From: Tianyu Lan <ltykernel@xxxxxxxxx> Sent: Monday, August 9, 2021 10:56 AM
> > Subject: [PATCH V3 05/13] HV: Add Write/Read MSR registers via ghcb page
> 
> See previous comments about tag in the Subject line.
> 
> > Hyper-V provides GHCB protocol to write Synthetic Interrupt
> > Controller MSR registers in Isolation VM with AMD SEV SNP
> > and these registers are emulated by hypervisor directly.
> > Hyper-V requires to write SINTx MSR registers twice. First
> > writes MSR via GHCB page to communicate with hypervisor
> > and then writes wrmsr instruction to talk with paravisor
> > which runs in VMPL0. Guest OS ID MSR also needs to be set
> > via GHCB.
> >
> > Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
> > ---
> > Change since v1:
> >          * Introduce sev_es_ghcb_hv_call_simple() and share code
> >            between SEV and Hyper-V code.
> > ---
> >  arch/x86/hyperv/hv_init.c       |  33 ++-------
> >  arch/x86/hyperv/ivm.c           | 110 +++++++++++++++++++++++++++++
> >  arch/x86/include/asm/mshyperv.h |  78 +++++++++++++++++++-
> >  arch/x86/include/asm/sev.h      |   3 +
> >  arch/x86/kernel/cpu/mshyperv.c  |   3 +
> >  arch/x86/kernel/sev-shared.c    |  63 ++++++++++-------
> >  drivers/hv/hv.c                 | 121 ++++++++++++++++++++++----------
> >  include/asm-generic/mshyperv.h  |  12 +++-
> >  8 files changed, 329 insertions(+), 94 deletions(-)
> >
> > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> > index b3683083208a..ab0b33f621e7 100644
> > --- a/arch/x86/hyperv/hv_init.c
> > +++ b/arch/x86/hyperv/hv_init.c
> > @@ -423,7 +423,7 @@ void __init hyperv_init(void)
> >  		goto clean_guest_os_id;
> >
> >  	if (hv_isolation_type_snp()) {
> > -		ms_hyperv.ghcb_base = alloc_percpu(void *);
> > +		ms_hyperv.ghcb_base = alloc_percpu(union hv_ghcb __percpu *);
> 
> union hv_ghcb isn't defined.  It is not added until patch 6 of the series.
> 

Ignore this comment.  My mistake.

Michael