Re: [PATCH v2 2/3] KVM:SVM: Add extended intercept support

[Jim Mattson <jmattson@google.com>]

On Tue, Jun 16, 2020 at 3:03 PM Babu Moger <babu.moger@amd.com> wrote:
>
> The new intercept bits have been added in vmcb control
> area to support the interception of INVPCID instruction.
>
> The following bit is added to the VMCB layout control area
> to control intercept of INVPCID:
>
> Byte Offset     Bit(s)          Function
> 14h             2               intercept INVPCID
>
> Add the interfaces to support these extended interception.
> Also update the tracing for extended intercepts.
>
> AMD documentation for INVPCID feature is available at "AMD64
> Architecture Programmer’s Manual Volume 2: System Programming,
> Pub. 24593 Rev. 3.34(or later)"
>
> The documentation can be obtained at the links below:
> Link: https://www.amd.com/system/files/TechDocs/24593.pdf
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537

Not your change, but this documentation is terrible. There is no
INVLPCID instruction, nor is there a PCID instruction.

> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
>  arch/x86/include/asm/svm.h |    3 ++-
>  arch/x86/kvm/svm/nested.c  |    6 +++++-
>  arch/x86/kvm/svm/svm.c     |    1 +
>  arch/x86/kvm/svm/svm.h     |   18 ++++++++++++++++++
>  arch/x86/kvm/trace.h       |   12 ++++++++----
>  5 files changed, 34 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> index 8a1f5382a4ea..62649fba8908 100644
> --- a/arch/x86/include/asm/svm.h
> +++ b/arch/x86/include/asm/svm.h
> @@ -61,7 +61,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
>         u32 intercept_dr;
>         u32 intercept_exceptions;
>         u64 intercept;
> -       u8 reserved_1[40];
> +       u32 intercept_extended;
> +       u8 reserved_1[36];

It seems like a more straightforward implementation would simply
change 'u64 intercept' to 'u32 intercept[3].'

>         u16 pause_filter_thresh;
>         u16 pause_filter_count;
>         u64 iopm_base_pa;
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 8a6db11dcb43..7f6d0f2533e2 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -121,6 +121,7 @@ void recalc_intercepts(struct vcpu_svm *svm)
>         c->intercept_dr = h->intercept_dr;
>         c->intercept_exceptions = h->intercept_exceptions;
>         c->intercept = h->intercept;
> +       c->intercept_extended = h->intercept_extended;
>
>         if (g->int_ctl & V_INTR_MASKING_MASK) {
>                 /* We only want the cr8 intercept bits of L1 */
> @@ -142,6 +143,7 @@ void recalc_intercepts(struct vcpu_svm *svm)
>         c->intercept_dr |= g->intercept_dr;
>         c->intercept_exceptions |= g->intercept_exceptions;
>         c->intercept |= g->intercept;
> +       c->intercept_extended |= g->intercept_extended;
>  }
>
>  static void copy_vmcb_control_area(struct vmcb_control_area *dst,
> @@ -151,6 +153,7 @@ static void copy_vmcb_control_area(struct vmcb_control_area *dst,
>         dst->intercept_dr         = from->intercept_dr;
>         dst->intercept_exceptions = from->intercept_exceptions;
>         dst->intercept            = from->intercept;
> +       dst->intercept_extended   = from->intercept_extended;
>         dst->iopm_base_pa         = from->iopm_base_pa;
>         dst->msrpm_base_pa        = from->msrpm_base_pa;
>         dst->tsc_offset           = from->tsc_offset;
> @@ -433,7 +436,8 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
>         trace_kvm_nested_intercepts(nested_vmcb->control.intercept_cr & 0xffff,
>                                     nested_vmcb->control.intercept_cr >> 16,
>                                     nested_vmcb->control.intercept_exceptions,
> -                                   nested_vmcb->control.intercept);
> +                                   nested_vmcb->control.intercept,
> +                                   nested_vmcb->control.intercept_extended);
>
>         /* Clear internal status */
>         kvm_clear_exception_queue(&svm->vcpu);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 9e333b91ff78..285e5e1ff518 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2801,6 +2801,7 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
>         pr_err("%-20s%04x\n", "dr_write:", control->intercept_dr >> 16);
>         pr_err("%-20s%08x\n", "exceptions:", control->intercept_exceptions);
>         pr_err("%-20s%016llx\n", "intercepts:", control->intercept);
> +       pr_err("%-20s%08x\n", "intercepts (extended):", control->intercept_extended);
>         pr_err("%-20s%d\n", "pause filter count:", control->pause_filter_count);
>         pr_err("%-20s%d\n", "pause filter threshold:",
>                control->pause_filter_thresh);
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 6ac4c00a5d82..935d08fac03d 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -311,6 +311,24 @@ static inline void clr_intercept(struct vcpu_svm *svm, int bit)
>         recalc_intercepts(svm);
>  }
>
> +static inline void set_extended_intercept(struct vcpu_svm *svm, int bit)
> +{
> +       struct vmcb *vmcb = get_host_vmcb(svm);
> +
> +       vmcb->control.intercept_extended |= (1U << bit);
> +
> +       recalc_intercepts(svm);
> +}
> +
> +static inline void clr_extended_intercept(struct vcpu_svm *svm, int bit)
> +{
> +       struct vmcb *vmcb = get_host_vmcb(svm);
> +
> +       vmcb->control.intercept_extended &= ~(1U << bit);
> +
> +       recalc_intercepts(svm);
> +}

You wouldn't need these new functions if you defined 'u32
intercept[3],' as I suggested above. Just change set_intercept and
clr_intercept to use __set_bit and __clear_bit.

>  static inline bool is_intercept(struct vcpu_svm *svm, int bit)
>  {
>         return (svm->vmcb->control.intercept & (1ULL << bit)) != 0;
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index b66432b015d2..5c841c42b33d 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -544,14 +544,16 @@ TRACE_EVENT(kvm_nested_vmrun,
>  );
>
>  TRACE_EVENT(kvm_nested_intercepts,
> -           TP_PROTO(__u16 cr_read, __u16 cr_write, __u32 exceptions, __u64 intercept),
> -           TP_ARGS(cr_read, cr_write, exceptions, intercept),
> +           TP_PROTO(__u16 cr_read, __u16 cr_write, __u32 exceptions, __u64 intercept,
> +                    __u32 extended),
> +           TP_ARGS(cr_read, cr_write, exceptions, intercept, extended),
>
>         TP_STRUCT__entry(
>                 __field(        __u16,          cr_read         )
>                 __field(        __u16,          cr_write        )
>                 __field(        __u32,          exceptions      )
>                 __field(        __u64,          intercept       )
> +               __field(        __u32,          extended        )
>         ),
>
>         TP_fast_assign(
> @@ -559,11 +561,13 @@ TRACE_EVENT(kvm_nested_intercepts,
>                 __entry->cr_write       = cr_write;
>                 __entry->exceptions     = exceptions;
>                 __entry->intercept      = intercept;
> +               __entry->extended       = extended;
>         ),
>
> -       TP_printk("cr_read: %04x cr_write: %04x excp: %08x intercept: %016llx",
> +       TP_printk("cr_read: %04x cr_write: %04x excp: %08x intercept: %016llx"
> +                 "intercept (extended): %08x",
>                 __entry->cr_read, __entry->cr_write, __entry->exceptions,
> -               __entry->intercept)
> +               __entry->intercept, __entry->extended)
>  );
>  /*
>   * Tracepoint for #VMEXIT while nested
>