linux-kernel - Re: [V2 PATCH 8/8] KVM: selftests: x86: xen: Execute cpu specific vmcall instruction

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Date:   Mon, 26 Sep 2022 16:37:26 -0700
From:   Vishal Annapurve <vannapurve@...gle.com>
To:     David Matlack <dmatlack@...gle.com>
Cc:     x86 <x86@...nel.org>, kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-kselftest@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>, shuah <shuah@...nel.org>,
        Ben Gardon <bgardon@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Oliver Upton <oupton@...gle.com>, peterx@...hat.com,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [V2 PATCH 8/8] KVM: selftests: x86: xen: Execute cpu specific
 vmcall instruction

On Wed, Sep 21, 2022 at 2:47 PM David Matlack <dmatlack@...gle.com> wrote:
>
> On Thu, Sep 15, 2022 at 12:04:48AM +0000, Vishal Annapurve wrote:
> > Update xen specific hypercall invocation to execute cpu specific vmcall
> > instructions.
> >
> > Suggested-by: Sean Christopherson <seanjc@...gle.com>
> > Signed-off-by: Vishal Annapurve <vannapurve@...gle.com>
> > ---
> >  .../selftests/kvm/x86_64/xen_shinfo_test.c    | 64 +++++++------------
> >  .../selftests/kvm/x86_64/xen_vmcall_test.c    | 14 ++--
> >  2 files changed, 34 insertions(+), 44 deletions(-)
> > ...
> > diff --git a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
> > index 88914d48c65e..e78f1b5d3af8 100644
> > --- a/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
> > +++ b/tools/testing/selftests/kvm/x86_64/xen_vmcall_test.c
> > @@ -37,10 +37,16 @@ static void guest_code(void)
> >       register unsigned long r9 __asm__("r9") = ARGVALUE(6);
> >
> >       /* First a direct invocation of 'vmcall' */
> > -     __asm__ __volatile__("vmcall" :
> > -                          "=a"(rax) :
> > -                          "a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
> > -                          "r"(r10), "r"(r8), "r"(r9));
> > +     if (is_amd_cpu())
> > +             __asm__ __volatile__("vmmcall" :
> > +                     "=a"(rax) :
> > +                     "a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
> > +                     "r"(r10), "r"(r8), "r"(r9));
> > +     else
> > +             __asm__ __volatile__("vmcall" :
> > +                     "=a"(rax) :
> > +                     "a"(rax), "D"(rdi), "S"(rsi), "d"(rdx),
> > +                     "r"(r10), "r"(r8), "r"(r9));
>
> Can we create common helper functions or macros for doing hypercalls to
> reduce the amount of duplicated inline assembly?
>

Ack, will fix this in the next series.

> >       GUEST_ASSERT(rax == RETVALUE);
> >
> >       /* Fill in the Xen hypercall page */
> > --
> > 2.37.2.789.g6183377224-goog
> >