Re: [RFC PATCH V3 01/11] x86/HV: Initialize GHCB page in Isolation VM

[Tianyu Lan <ltykernel@xxxxxxxxx>]

Hi Joerg：
        Thanks for your review.


On 6/9/2021 8:38 PM, Joerg Roedel wrote:
> On Sun, May 30, 2021 at 11:06:18AM -0400, Tianyu Lan wrote:
> > From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
> >
> > Hyper-V exposes GHCB page via SEV ES GHCB MSR for SNP guest
> > to communicate with hypervisor. Map GHCB page for all
> > cpus to read/write MSR register and submit hvcall request
> > via GHCB.
> >
> > Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
> > ---
> >   arch/x86/hyperv/hv_init.c       | 60 ++++++++++++++++++++++++++++++---
> >   arch/x86/include/asm/mshyperv.h |  2 ++
> >   include/asm-generic/mshyperv.h  |  2 ++
> >   3 files changed, 60 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> > index bb0ae4b5c00f..dc74d01cb859 100644
> > --- a/arch/x86/hyperv/hv_init.c
> > +++ b/arch/x86/hyperv/hv_init.c
> > @@ -60,6 +60,9 @@ static int hv_cpu_init(unsigned int cpu)
> >         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
> >         void **input_arg;
> >         struct page *pg;
> > +       u64 ghcb_gpa;
> > +       void *ghcb_va;
> > +       void **ghcb_base;
> Any reason you can't reuse the SEV-ES support code in the Linux kernel?
> It already has code to setup GHCBs for all vCPUs.
>
> I see that you don't need #VC handling in your SNP VMs because of the
> paravisor running underneath it, but just re-using the GHCB setup code
> shouldn't be too hard.
Thanks for your suggestion. I will have a try to use SEV-ES code.