RE: [PATCH v3 02/11] KVM: SVM: Change intercept_cr to generic intercepts

[Babu Moger]

> -----Original Message-----
> From: Jim Mattson <jmattson@xxxxxxxxxx>
> Sent: Tuesday, July 28, 2020 6:56 PM
> To: Moger, Babu <Babu.Moger@xxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>; Vitaly Kuznetsov
> <vkuznets@xxxxxxxxxx>; Wanpeng Li <wanpengli@xxxxxxxxxxx>; Sean
> Christopherson <sean.j.christopherson@xxxxxxxxx>; kvm list
> <kvm@xxxxxxxxxxxxxxx>; Joerg Roedel <joro@xxxxxxxxxx>; the arch/x86
> maintainers <x86@xxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>; Ingo
> Molnar <mingo@xxxxxxxxxx>; Borislav Petkov <bp@xxxxxxxxx>; H . Peter Anvin
> <hpa@xxxxxxxxx>; Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Subject: Re: [PATCH v3 02/11] KVM: SVM: Change intercept_cr to generic
> intercepts
> 
> On Tue, Jul 28, 2020 at 4:38 PM Babu Moger <babu.moger@xxxxxxx> wrote:
> >
> > Change intercept_cr to generic intercepts in vmcb_control_area.
> > Use the new __set_intercept, __clr_intercept and __is_intercept where
> > applicable.
> >
> > Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> > ---
> >  arch/x86/include/asm/svm.h |   42 ++++++++++++++++++++++++++++++++----
> ------
> >  arch/x86/kvm/svm/nested.c  |   26 +++++++++++++++++---------
> >  arch/x86/kvm/svm/svm.c     |    4 ++--
> >  arch/x86/kvm/svm/svm.h     |    6 +++---
> >  4 files changed, 54 insertions(+), 24 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> > index 8a1f5382a4ea..d4739f4eae63 100644
> > --- a/arch/x86/include/asm/svm.h
> > +++ b/arch/x86/include/asm/svm.h
> > @@ -4,6 +4,37 @@
> >
> >  #include <uapi/asm/svm.h>
> >
> > +/*
> > + * VMCB Control Area intercept bits starting
> > + * at Byte offset 000h (Vector 0).
> > + */
> > +
> > +enum vector_offset {
> > +       CR_VECTOR = 0,
> > +       MAX_VECTORS,
> > +};
> > +
> > +enum {
> > +       /* Byte offset 000h (Vector 0) */
> > +       INTERCEPT_CR0_READ = 0,
> > +       INTERCEPT_CR1_READ,
> > +       INTERCEPT_CR2_READ,
> > +       INTERCEPT_CR3_READ,
> > +       INTERCEPT_CR4_READ,
> > +       INTERCEPT_CR5_READ,
> > +       INTERCEPT_CR6_READ,
> > +       INTERCEPT_CR7_READ,
> > +       INTERCEPT_CR8_READ,
> > +       INTERCEPT_CR0_WRITE = 16,
> > +       INTERCEPT_CR1_WRITE,
> > +       INTERCEPT_CR2_WRITE,
> > +       INTERCEPT_CR3_WRITE,
> > +       INTERCEPT_CR4_WRITE,
> > +       INTERCEPT_CR5_WRITE,
> > +       INTERCEPT_CR6_WRITE,
> > +       INTERCEPT_CR7_WRITE,
> > +       INTERCEPT_CR8_WRITE,
> > +};
> >
> >  enum {
> >         INTERCEPT_INTR,
> > @@ -57,7 +88,7 @@ enum {
> >
> >
> >  struct __attribute__ ((__packed__)) vmcb_control_area {
> > -       u32 intercept_cr;
> > +       u32 intercepts[MAX_VECTORS];
> >         u32 intercept_dr;
> >         u32 intercept_exceptions;
> >         u64 intercept;
> > @@ -240,15 +271,6 @@ struct __attribute__ ((__packed__)) vmcb {
> > #define SVM_SELECTOR_READ_MASK SVM_SELECTOR_WRITE_MASK  #define
> > SVM_SELECTOR_CODE_MASK (1 << 3)
> >
> > -#define INTERCEPT_CR0_READ     0
> > -#define INTERCEPT_CR3_READ     3
> > -#define INTERCEPT_CR4_READ     4
> > -#define INTERCEPT_CR8_READ     8
> > -#define INTERCEPT_CR0_WRITE    (16 + 0)
> > -#define INTERCEPT_CR3_WRITE    (16 + 3)
> > -#define INTERCEPT_CR4_WRITE    (16 + 4)
> > -#define INTERCEPT_CR8_WRITE    (16 + 8)
> > -
> >  #define INTERCEPT_DR0_READ     0
> >  #define INTERCEPT_DR1_READ     1
> >  #define INTERCEPT_DR2_READ     2
> > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> > index 6bceafb19108..46f5c82d9b45 100644
> > --- a/arch/x86/kvm/svm/nested.c
> > +++ b/arch/x86/kvm/svm/nested.c
> > @@ -105,6 +105,7 @@ static void nested_svm_uninit_mmu_context(struct
> > kvm_vcpu *vcpu)  void recalc_intercepts(struct vcpu_svm *svm)  {
> >         struct vmcb_control_area *c, *h, *g;
> > +       unsigned int i;
> >
> >         mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
> >
> > @@ -117,15 +118,17 @@ void recalc_intercepts(struct vcpu_svm *svm)
> >
> >         svm->nested.host_intercept_exceptions =
> > h->intercept_exceptions;
> >
> > -       c->intercept_cr = h->intercept_cr;
> > +       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;
> >
> >         if (g->int_ctl & V_INTR_MASKING_MASK) {
> >                 /* We only want the cr8 intercept bits of L1 */
> > -               c->intercept_cr &= ~(1U << INTERCEPT_CR8_READ);
> > -               c->intercept_cr &= ~(1U << INTERCEPT_CR8_WRITE);
> > +               __clr_intercept(&c->intercepts, INTERCEPT_CR8_READ);
> > +               __clr_intercept(&c->intercepts, INTERCEPT_CR8_WRITE);
> 
> Why the direct calls to the __clr_intercept worker function? Can't these be calls
> to clr_cr_intercept()?
> Likewise throughout.

This code uses the address to clear the bits.  So called __clr_intercept
directly. The call clr_cr_intercept() passes the structure vcpu_svm and
then uses get_host_vmcb to get the address.