linux-kernel - Re: [PATCH v3 02/11] KVM: SVM: Change intercept

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Date:   Tue, 28 Jul 2020 16:56:21 -0700
From:   Jim Mattson <jmattson@...gle.com>
To:     Babu Moger <babu.moger@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        kvm list <kvm@...r.kernel.org>, Joerg Roedel <joro@...tes.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
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@....com> 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@....com>
> ---
>  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.