Re: [PATCH 1/5] xen/vm_event: Added support for XSETBV events

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 06/05/15 18:12, Razvan Cojocaru wrote:
> This patch adds XSETBV (XCR) vm_events.
>
> Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
> ---
>  tools/libxc/include/xenctrl.h   |    2 ++
>  tools/libxc/xc_monitor.c        |   15 +++++++++++++++
>  xen/arch/x86/hvm/event.c        |   16 ++++++++++++++++
>  xen/arch/x86/hvm/hvm.c          |    2 ++
>  xen/arch/x86/monitor.c          |   16 ++++++++++++++++
>  xen/include/asm-x86/domain.h    |    2 ++
>  xen/include/asm-x86/hvm/event.h |    1 +
>  xen/include/public/domctl.h     |    6 ++++++
>  xen/include/public/vm_event.h   |    8 ++++++++
>  9 files changed, 68 insertions(+)
>
> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> index 6994c51..1aa4f87 100644
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -2337,6 +2337,8 @@ int xc_monitor_mov_to_msr(xc_interface *xch, domid_t domain_id, bool enable,
>  int xc_monitor_singlestep(xc_interface *xch, domid_t domain_id, bool enable);
>  int xc_monitor_software_breakpoint(xc_interface *xch, domid_t domain_id,
>                                     bool enable);
> +int xc_monitor_xsetbv(xc_interface *xch, domid_t domain_id, bool enable,
> +                      bool sync);
>  
>  /***
>   * Memory sharing operations.
> diff --git a/tools/libxc/xc_monitor.c b/tools/libxc/xc_monitor.c
> index 87ad968..aec2f4a 100644
> --- a/tools/libxc/xc_monitor.c
> +++ b/tools/libxc/xc_monitor.c
> @@ -135,3 +135,18 @@ int xc_monitor_singlestep(xc_interface *xch, domid_t domain_id,
>  
>      return do_domctl(xch, &domctl);
>  }
> +
> +int xc_monitor_xsetbv(xc_interface *xch, domid_t domain_id, bool enable,
> +                      bool sync)
> +{
> +    DECLARE_DOMCTL;
> +
> +    domctl.cmd = XEN_DOMCTL_monitor_op;
> +    domctl.domain = domain_id;
> +    domctl.u.monitor_op.op = enable ? XEN_DOMCTL_MONITOR_OP_ENABLE
> +                                    : XEN_DOMCTL_MONITOR_OP_DISABLE;
> +    domctl.u.monitor_op.event = XEN_DOMCTL_MONITOR_EVENT_XSETBV;
> +    domctl.u.monitor_op.u.xsetbv.sync = sync;
> +
> +    return do_domctl(xch, &domctl);
> +}
> diff --git a/xen/arch/x86/hvm/event.c b/xen/arch/x86/hvm/event.c
> index 9d5f9f3..5b869c8 100644
> --- a/xen/arch/x86/hvm/event.c
> +++ b/xen/arch/x86/hvm/event.c
> @@ -151,6 +151,22 @@ void hvm_event_msr(unsigned int msr, uint64_t value)
>          hvm_event_traps(1, &req);
>  }
>  
> +void hvm_event_xsetbv(unsigned long xcr, uint64_t value)

Architecturally, the XCR index is specified in ecx, making it only 32
bits wide. 

> +{
> +    struct vcpu *curr = current;
> +    struct arch_domain *currad = &current->domain->arch;
> +
> +    vm_event_request_t req = {
> +        .reason = VM_EVENT_REASON_XSETBV,
> +        .vcpu_id = curr->vcpu_id,
> +        .u.xsetbv.xcr = xcr,
> +        .u.xsetbv.value = value,
> +    };
> +
> +    if ( currad->monitor.xsetbv_enabled )
> +        hvm_event_traps(currad->monitor.xsetbv_sync, &req);
> +}
> +
>  int hvm_event_int3(unsigned long gla)
>  {
>      int rc = 0;
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 3a09439..86f9885 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -2966,6 +2966,8 @@ int hvm_handle_xsetbv(u32 index, u64 new_bv)
>  {
>      struct segment_register sreg;
>  
> +    hvm_event_xsetbv(index, new_bv);
> +
>      hvm_get_segment_register(current, x86_seg_ss, &sreg);
>      if ( sreg.attr.fields.dpl != 0 )
>          goto err;
> diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
> index d7b1c18..6823a84 100644
> --- a/xen/arch/x86/monitor.c
> +++ b/xen/arch/x86/monitor.c
> @@ -178,6 +178,22 @@ int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop)
>          break;
>      }
>  
> +    case XEN_DOMCTL_MONITOR_EVENT_XSETBV:
> +    {
> +        bool_t status = ad->monitor.xsetbv_enabled;
> +
> +        rc = status_check(mop, status);
> +        if ( rc )
> +            return rc;
> +
> +        ad->monitor.xsetbv_sync = mop->u.xsetbv.sync;
> +
> +        domain_pause(d);
> +        ad->monitor.xsetbv_enabled = !status;
> +        domain_unpause(d);
> +        break;
> +    }
> +
>      default:
>          return -EOPNOTSUPP;
>  
> diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
> index 3f83e8b..452a9b3 100644
> --- a/xen/include/asm-x86/domain.h
> +++ b/xen/include/asm-x86/domain.h
> @@ -354,6 +354,8 @@ struct arch_domain
>          uint16_t mov_to_msr_extended         : 1;
>          uint16_t singlestep_enabled          : 1;
>          uint16_t software_breakpoint_enabled : 1;
> +        uint16_t xsetbv_enabled              : 1;
> +        uint16_t xsetbv_sync                 : 1;
>      } monitor;
>  
>      /* Mem_access emulation control */
> diff --git a/xen/include/asm-x86/hvm/event.h b/xen/include/asm-x86/hvm/event.h
> index bb757a1..b2cf3bc 100644
> --- a/xen/include/asm-x86/hvm/event.h
> +++ b/xen/include/asm-x86/hvm/event.h
> @@ -23,6 +23,7 @@ void hvm_event_cr0(unsigned long value, unsigned long old);
>  void hvm_event_cr3(unsigned long value, unsigned long old);
>  void hvm_event_cr4(unsigned long value, unsigned long old);
>  void hvm_event_msr(unsigned int msr, uint64_t value);
> +void hvm_event_xsetbv(unsigned long xcr, uint64_t value);
>  /* Called for current VCPU: returns -1 if no listener */
>  int hvm_event_int3(unsigned long gla);
>  int hvm_event_single_step(unsigned long gla);
> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> index 10b51ef..b866e33 100644
> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -1018,6 +1018,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_psr_cmt_op_t);
>  #define XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR            3
>  #define XEN_DOMCTL_MONITOR_EVENT_SINGLESTEP            4
>  #define XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT   5
> +#define XEN_DOMCTL_MONITOR_EVENT_XSETBV                6
>  
>  struct xen_domctl_monitor_op {
>      uint32_t op; /* XEN_DOMCTL_MONITOR_OP_* */
> @@ -1038,6 +1039,11 @@ struct xen_domctl_monitor_op {
>              /* Enable the capture of an extended set of MSRs */
>              uint8_t extended_capture;
>          } mov_to_msr;
> +
> +        struct {
> +            /* Pause vCPU until response */
> +            uint8_t sync;
> +        } xsetbv;
>      } u;
>  };
>  typedef struct xen_domctl__op xen_domctl_monitor_op_t;
> diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
> index c7426de..71fe9ba 100644
> --- a/xen/include/public/vm_event.h
> +++ b/xen/include/public/vm_event.h
> @@ -72,6 +72,8 @@
>  #define VM_EVENT_REASON_SOFTWARE_BREAKPOINT     8
>  /* Single-step (e.g. MTF) */
>  #define VM_EVENT_REASON_SINGLESTEP              9
> +/* An XCR was updated. */
> +#define VM_EVENT_REASON_XSETBV                 10
>  
>  /*
>   * Using a custom struct (not hvm_hw_cpu) so as to not fill
> @@ -186,6 +188,11 @@ struct vm_event_sharing {
>      uint32_t _pad;
>  };
>  
> +struct vm_event_xsetbv {
> +    uint64_t xcr;
> +    uint64_t value;
> +};
> +

In an effort to be architecture neutral, it might be an idea to have
something like

struct vm_event_write_cr {
    uint64_t index;
    uint64_t old_val, new_val;
};

And have a per-arch index of control registers, such as

X86_CR0
X86_CR3
X86_CR4
X86_XCR0
...
ARM32_$foo

(See also my reply to Tim on this thread)

~Andrew

>  typedef struct vm_event_st {
>      uint32_t version;   /* VM_EVENT_INTERFACE_VERSION */
>      uint32_t flags;     /* VM_EVENT_FLAG_* */
> @@ -200,6 +207,7 @@ typedef struct vm_event_st {
>          struct vm_event_mov_to_msr            mov_to_msr;
>          struct vm_event_debug                 software_breakpoint;
>          struct vm_event_debug                 singlestep;
> +        struct vm_event_xsetbv                xsetbv;
>      } u;
>  
>      union {