Re: [Xen-devel] [PATCH v2 1/2] x86/monitor: add masking support for write_ctrlreg events

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Tue, May 30, 2017 at 3:46 AM, Petre Pircalabu
<ppircalabu@xxxxxxxxxxxxxxx> wrote:
> Add support for filtering out the write_ctrlreg monitor events if they
> are generated only by changing certains bits.
> A new parameter (bitmask) was added to the xc_monitor_write_ctrlreg
> function in order to mask the event generation if the changed bits are
> set.
>
> Signed-off-by: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>

Acked-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>

> ---
>  tools/libxc/include/xenctrl.h | 2 +-
>  tools/libxc/xc_monitor.c      | 3 ++-
>  xen/arch/x86/hvm/monitor.c    | 3 ++-
>  xen/arch/x86/monitor.c        | 6 ++++++
>  xen/include/asm-x86/domain.h  | 1 +
>  xen/include/public/domctl.h   | 7 ++++++-
>  6 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> index 1629f41..8c26cb4 100644
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -1999,7 +1999,7 @@ int xc_monitor_get_capabilities(xc_interface *xch, 
> domid_t domain_id,
>                                  uint32_t *capabilities);
>  int xc_monitor_write_ctrlreg(xc_interface *xch, domid_t domain_id,
>                               uint16_t index, bool enable, bool sync,
> -                             bool onchangeonly);
> +                             uint64_t bitmask, bool onchangeonly);
>  /*
>   * A list of MSR indices can usually be found in 
> /usr/include/asm/msr-index.h.
>   * Please consult the Intel/AMD manuals for more information on
> diff --git a/tools/libxc/xc_monitor.c b/tools/libxc/xc_monitor.c
> index f99b6e3..70648d7 100644
> --- a/tools/libxc/xc_monitor.c
> +++ b/tools/libxc/xc_monitor.c
> @@ -70,7 +70,7 @@ int xc_monitor_get_capabilities(xc_interface *xch, domid_t 
> domain_id,
>
>  int xc_monitor_write_ctrlreg(xc_interface *xch, domid_t domain_id,
>                               uint16_t index, bool enable, bool sync,
> -                             bool onchangeonly)
> +                             uint64_t bitmask, bool onchangeonly)
>  {
>      DECLARE_DOMCTL;
>
> @@ -82,6 +82,7 @@ int xc_monitor_write_ctrlreg(xc_interface *xch, domid_t 
> domain_id,
>      domctl.u.monitor_op.u.mov_to_cr.index = index;
>      domctl.u.monitor_op.u.mov_to_cr.sync = sync;
>      domctl.u.monitor_op.u.mov_to_cr.onchangeonly = onchangeonly;
> +    domctl.u.monitor_op.u.mov_to_cr.bitmask = bitmask;
>
>      return do_domctl(xch, &domctl);
>  }
> diff --git a/xen/arch/x86/hvm/monitor.c b/xen/arch/x86/hvm/monitor.c
> index bde5fd0..a7ccfc4 100644
> --- a/xen/arch/x86/hvm/monitor.c
> +++ b/xen/arch/x86/hvm/monitor.c
> @@ -38,7 +38,8 @@ bool_t hvm_monitor_cr(unsigned int index, unsigned long 
> value, unsigned long old
>
>      if ( (ad->monitor.write_ctrlreg_enabled & ctrlreg_bitmask) &&
>           (!(ad->monitor.write_ctrlreg_onchangeonly & ctrlreg_bitmask) ||
> -          value != old) )
> +          value != old) &&
> +         (!((value ^ old) & ad->monitor.write_ctrlreg_mask[index])) )
>      {
>          bool_t sync = !!(ad->monitor.write_ctrlreg_sync & ctrlreg_bitmask);
>
> diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
> index 449c64c..d02d2ea 100644
> --- a/xen/arch/x86/monitor.c
> +++ b/xen/arch/x86/monitor.c
> @@ -155,9 +155,15 @@ int arch_monitor_domctl_event(struct domain *d,
>              ad->monitor.write_ctrlreg_onchangeonly &= ~ctrlreg_bitmask;
>
>          if ( requested_status )
> +        {
> +            ad->monitor.write_ctrlreg_mask[mop->u.mov_to_cr.index] = 
> mop->u.mov_to_cr.bitmask;
>              ad->monitor.write_ctrlreg_enabled |= ctrlreg_bitmask;
> +        }
>          else
> +        {
> +            ad->monitor.write_ctrlreg_mask[mop->u.mov_to_cr.index] = 0;
>              ad->monitor.write_ctrlreg_enabled &= ~ctrlreg_bitmask;
> +        }
>
>          if ( VM_EVENT_X86_CR3 == mop->u.mov_to_cr.index )
>          {
> diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
> index 924caac..27d80ee 100644
> --- a/xen/include/asm-x86/domain.h
> +++ b/xen/include/asm-x86/domain.h
> @@ -406,6 +406,7 @@ struct arch_domain
>          unsigned int cpuid_enabled               : 1;
>          unsigned int descriptor_access_enabled   : 1;
>          struct monitor_msr_bitmap *msr_bitmap;
> +        uint64_t write_ctrlreg_mask[4];
>      } monitor;
>
>      /* Mem_access emulation control */
> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> index e6cf211..652fb17 100644
> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -37,7 +37,7 @@
>  #include "hvm/save.h"
>  #include "memory.h"
>
> -#define XEN_DOMCTL_INTERFACE_VERSION 0x0000000d
> +#define XEN_DOMCTL_INTERFACE_VERSION 0x0000000e
>
>  /*
>   * NB. xen_domctl.domain is an IN/OUT parameter for this operation.
> @@ -1107,6 +1107,11 @@ struct xen_domctl_monitor_op {
>              uint8_t sync;
>              /* Send event only on a change of value */
>              uint8_t onchangeonly;
> +            /*
> +             * Send event only if the changed bit in the control register
> +             * is not masked.
> +             */
> +            uint64_aligned_t bitmask;
>          } mov_to_cr;
>
>          struct {
> --
> 2.7.4

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