RE: [PATCH v3 03/11] KVM: SVM: Change intercept_dr to generic intercepts

[Babu Moger <babu.moger@amd.com>]

> -----Original Message-----
> From: Jim Mattson <jmattson@google.com>
> Sent: Tuesday, July 28, 2020 6:59 PM
> To: Moger, Babu <Babu.Moger@amd.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>; Vitaly Kuznetsov
> <vkuznets@redhat.com>; Wanpeng Li <wanpengli@tencent.com>; Sean
> Christopherson <sean.j.christopherson@intel.com>; kvm list
> <kvm@vger.kernel.org>; Joerg Roedel <joro@8bytes.org>; the arch/x86
> maintainers <x86@kernel.org>; LKML <linux-kernel@vger.kernel.org>; Ingo
> Molnar <mingo@redhat.com>; Borislav Petkov <bp@alien8.de>; H . Peter Anvin
> <hpa@zytor.com>; Thomas Gleixner <tglx@linutronix.de>
> Subject: Re: [PATCH v3 03/11] KVM: SVM: Change intercept_dr to generic
> intercepts
> 
> On Tue, Jul 28, 2020 at 4:38 PM Babu Moger <babu.moger@amd.com> wrote:
> >
> > Modify intercept_dr to generic intercepts in vmcb_control_area.
> > Use generic __set_intercept, __clr_intercept and __is_intercept to
> > set/clear/test the intercept_dr bits.
> >
> > Signed-off-by: Babu Moger <babu.moger@amd.com>
> > ---
> >  arch/x86/include/asm/svm.h |   36 ++++++++++++++++++------------------
> >  arch/x86/kvm/svm/nested.c  |    6 +-----
> >  arch/x86/kvm/svm/svm.c     |    4 ++--
> >  arch/x86/kvm/svm/svm.h     |   34 +++++++++++++++++-----------------
> >  4 files changed, 38 insertions(+), 42 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> > index d4739f4eae63..ffc89d8e4fcb 100644
> > --- a/arch/x86/include/asm/svm.h
> > +++ b/arch/x86/include/asm/svm.h
> > @@ -11,6 +11,7 @@
> >
> >  enum vector_offset {
> >         CR_VECTOR = 0,
> > +       DR_VECTOR,
> >         MAX_VECTORS,
> >  };
> >
> > @@ -34,6 +35,23 @@ enum {
> >         INTERCEPT_CR6_WRITE,
> >         INTERCEPT_CR7_WRITE,
> >         INTERCEPT_CR8_WRITE,
> > +       /* Byte offset 004h (Vector 1) */
> > +       INTERCEPT_DR0_READ = 32,
> > +       INTERCEPT_DR1_READ,
> > +       INTERCEPT_DR2_READ,
> > +       INTERCEPT_DR3_READ,
> > +       INTERCEPT_DR4_READ,
> > +       INTERCEPT_DR5_READ,
> > +       INTERCEPT_DR6_READ,
> > +       INTERCEPT_DR7_READ,
> > +       INTERCEPT_DR0_WRITE = 48,
> > +       INTERCEPT_DR1_WRITE,
> > +       INTERCEPT_DR2_WRITE,
> > +       INTERCEPT_DR3_WRITE,
> > +       INTERCEPT_DR4_WRITE,
> > +       INTERCEPT_DR5_WRITE,
> > +       INTERCEPT_DR6_WRITE,
> > +       INTERCEPT_DR7_WRITE,
> >  };
> >
> >  enum {
> > @@ -89,7 +107,6 @@ enum {
> >
> >  struct __attribute__ ((__packed__)) vmcb_control_area {
> >         u32 intercepts[MAX_VECTORS];
> > -       u32 intercept_dr;
> >         u32 intercept_exceptions;
> >         u64 intercept;
> >         u8 reserved_1[40];
> > @@ -271,23 +288,6 @@ struct __attribute__ ((__packed__)) vmcb {
> > #define SVM_SELECTOR_READ_MASK SVM_SELECTOR_WRITE_MASK  #define
> > SVM_SELECTOR_CODE_MASK (1 << 3)
> >
> > -#define INTERCEPT_DR0_READ     0
> > -#define INTERCEPT_DR1_READ     1
> > -#define INTERCEPT_DR2_READ     2
> > -#define INTERCEPT_DR3_READ     3
> > -#define INTERCEPT_DR4_READ     4
> > -#define INTERCEPT_DR5_READ     5
> > -#define INTERCEPT_DR6_READ     6
> > -#define INTERCEPT_DR7_READ     7
> > -#define INTERCEPT_DR0_WRITE    (16 + 0)
> > -#define INTERCEPT_DR1_WRITE    (16 + 1)
> > -#define INTERCEPT_DR2_WRITE    (16 + 2)
> > -#define INTERCEPT_DR3_WRITE    (16 + 3)
> > -#define INTERCEPT_DR4_WRITE    (16 + 4)
> > -#define INTERCEPT_DR5_WRITE    (16 + 5)
> > -#define INTERCEPT_DR6_WRITE    (16 + 6)
> > -#define INTERCEPT_DR7_WRITE    (16 + 7)
> > -
> >  #define SVM_EVTINJ_VEC_MASK 0xff
> >
> >  #define SVM_EVTINJ_TYPE_SHIFT 8
> > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> > index 46f5c82d9b45..71ca89afb2a3 100644
> > --- a/arch/x86/kvm/svm/nested.c
> > +++ b/arch/x86/kvm/svm/nested.c
> > @@ -121,7 +121,6 @@ void recalc_intercepts(struct vcpu_svm *svm)
> >         for (i = 0; i < MAX_VECTORS; i++)
> >                 c->intercepts[i] = h->intercepts[i];
> >
> > -       c->intercept_dr = h->intercept_dr;
> >         c->intercept_exceptions = h->intercept_exceptions;
> >         c->intercept = h->intercept;
> >
> > @@ -144,7 +143,6 @@ void recalc_intercepts(struct vcpu_svm *svm)
> >         for (i = 0; i < MAX_VECTORS; i++)
> >                 c->intercepts[i] |= g->intercepts[i];
> >
> > -       c->intercept_dr |= g->intercept_dr;
> >         c->intercept_exceptions |= g->intercept_exceptions;
> >         c->intercept |= g->intercept;
> >  }
> > @@ -157,7 +155,6 @@ static void copy_vmcb_control_area(struct
> vmcb_control_area *dst,
> >         for (i = 0; i < MAX_VECTORS; i++)
> >                 dst->intercepts[i] = from->intercepts[i];
> >
> > -       dst->intercept_dr         = from->intercept_dr;
> >         dst->intercept_exceptions = from->intercept_exceptions;
> >         dst->intercept            = from->intercept;
> >         dst->iopm_base_pa         = from->iopm_base_pa;
> > @@ -717,8 +714,7 @@ static int nested_svm_intercept(struct vcpu_svm
> *svm)
> >                 break;
> >         }
> >         case SVM_EXIT_READ_DR0 ... SVM_EXIT_WRITE_DR7: {
> > -               u32 bit = 1U << (exit_code - SVM_EXIT_READ_DR0);
> > -               if (svm->nested.ctl.intercept_dr & bit)
> > +               if (__is_intercept(&svm->nested.ctl.intercepts,
> > + exit_code))
> 
> Can I assume that all of these __<function> calls will become <function> calls
> when the grand unification is done? (Maybe I should just look ahead.)

There are two types of calls here.

1. Calls like set_cr_intercept, clr_cr_intercept, set_dr_intercept,
clr_dr_intercept, set_exception_intercept, clr_exception_intercept.
These calls pass svm data structure. I replaced these calls with either
set_intercept or clr_intercept because we have combined all the intercept
vectors into one 32 bit array.

2. Some calls sets or clears the bit directly like
  c->intercept_cr &= ~(1U << INTERCEPT_CR8_READ);
  Replaced these with __clr_intercept or __set_intercepts.

There is a scope to make all these calls set_intercept or clr_intercept.
These calls use another call get_host_vmcb to get the address. We can take
that up as next cleanup.