Re: [PATCH v2 1/2] xen+tools: Report Interrupt Controller Virtualization capabilities on x86

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, Feb 07, 2022 at 06:21:00PM +0000, Jane Malalane wrote:
> Add XEN_SYSCTL_PHYSCAP_ARCH_ASSISTED_xapic and
> XEN_SYSCTL_PHYSCAP_ARCH_ASSISTED_x2apic to report accelerated xapic
> and x2apic, on x86 hardware.
> No such features are currently implemented on AMD hardware.
> 
> For that purpose, also add an arch-specific "capabilities" parameter
> to struct xen_sysctl_physinfo.
> 
> Signed-off-by: Jane Malalane <jane.malalane@xxxxxxxxxx>
> Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Tag order should be inverted, first Suggested-by, then SoB.

> ---
> CC: Wei Liu <wl@xxxxxxx>
> CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> CC: Juergen Gross <jgross@xxxxxxxx>
> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: George Dunlap <george.dunlap@xxxxxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> CC: Julien Grall <julien@xxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
> CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
> CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
> CC: Kevin Tian <kevin.tian@xxxxxxxxx>
> CC: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
> 
> v2:
>  * Use one macro LIBXL_HAVE_PHYSINFO_ASSISTED_APIC instead of two
>  * Pass xcpyshinfo as a pointer in libxl__arch_get_physinfo
>  * Set assisted_x{2}apic_available to be conditional upon "bsp" and
>    annotate it with __ro_after_init
>  * Change XEN_SYSCTL_PHYSCAP_ARCH_ASSISTED_X{2}APIC to
>    .._X86_ASSISTED_X{2}APIC
>  * Keep XEN_SYSCTL_PHYSCAP_X86_ASSISTED_X{2}APIC contained within
>    sysctl.h
>  * Fix padding introduced in struct xen_sysctl_physinfo and bump
>    XEN_SYSCTL_INTERFACE_VERSION
> ---
>  tools/golang/xenlight/helpers.gen.go |  4 ++++
>  tools/golang/xenlight/types.gen.go   |  6 ++++++
>  tools/include/libxl.h                |  7 +++++++
>  tools/libs/light/libxl.c             |  3 +++
>  tools/libs/light/libxl_arch.h        |  4 ++++
>  tools/libs/light/libxl_arm.c         |  5 +++++
>  tools/libs/light/libxl_types.idl     |  2 ++
>  tools/libs/light/libxl_x86.c         | 11 +++++++++++
>  tools/ocaml/libs/xc/xenctrl.ml       |  5 +++++
>  tools/ocaml/libs/xc/xenctrl.mli      |  5 +++++
>  tools/xl/xl_info.c                   |  6 ++++--
>  xen/arch/x86/hvm/vmx/vmcs.c          |  9 +++++++++
>  xen/arch/x86/include/asm/domain.h    |  3 +++
>  xen/arch/x86/sysctl.c                |  7 +++++++
>  xen/include/public/sysctl.h          |  8 +++++++-
>  15 files changed, 82 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/golang/xenlight/helpers.gen.go 
> b/tools/golang/xenlight/helpers.gen.go
> index b746ff1081..dd4e6c9f14 100644
> --- a/tools/golang/xenlight/helpers.gen.go
> +++ b/tools/golang/xenlight/helpers.gen.go
> @@ -3373,6 +3373,8 @@ x.CapVmtrace = bool(xc.cap_vmtrace)
>  x.CapVpmu = bool(xc.cap_vpmu)
>  x.CapGnttabV1 = bool(xc.cap_gnttab_v1)
>  x.CapGnttabV2 = bool(xc.cap_gnttab_v2)
> +x.CapAssistedXapic = bool(xc.cap_assisted_xapic)
> +x.CapAssistedX2Apic = bool(xc.cap_assisted_x2apic)
>  
>   return nil}
>  
> @@ -3407,6 +3409,8 @@ xc.cap_vmtrace = C.bool(x.CapVmtrace)
>  xc.cap_vpmu = C.bool(x.CapVpmu)
>  xc.cap_gnttab_v1 = C.bool(x.CapGnttabV1)
>  xc.cap_gnttab_v2 = C.bool(x.CapGnttabV2)
> +xc.cap_assisted_xapic = C.bool(x.CapAssistedXapic)
> +xc.cap_assisted_x2apic = C.bool(x.CapAssistedX2Apic)
>  
>   return nil
>   }
> diff --git a/tools/golang/xenlight/types.gen.go 
> b/tools/golang/xenlight/types.gen.go
> index b1e84d5258..5f384b767c 100644
> --- a/tools/golang/xenlight/types.gen.go
> +++ b/tools/golang/xenlight/types.gen.go
> @@ -389,6 +389,10 @@ RunHotplugScripts Defbool
>  DriverDomain Defbool
>  Passthrough Passthrough
>  XendSuspendEvtchnCompat Defbool
> +ArchX86 struct {
> +AssistedXapic Defbool
> +AssistedX2Apic Defbool

Don't you need some indentation here?

Also name would better be Assistedx{2}APIC IMO if possible. Having a
capital 'X' and lowercase 'apic' looks really strange.

> +}
>  }
>  
>  type DomainRestoreParams struct {
> @@ -1014,6 +1018,8 @@ CapVmtrace bool
>  CapVpmu bool
>  CapGnttabV1 bool
>  CapGnttabV2 bool
> +CapAssistedXApic bool
> +CapAssistedX2apic bool
>  }
>  
>  type Connectorinfo struct {
> diff --git a/tools/include/libxl.h b/tools/include/libxl.h
> index 2bbbd21f0b..924e142628 100644
> --- a/tools/include/libxl.h
> +++ b/tools/include/libxl.h
> @@ -528,6 +528,13 @@
>  #define LIBXL_HAVE_MAX_GRANT_VERSION 1
>  
>  /*
> + * LIBXL_HAVE_PHYSINFO_ASSISTED_APIC indicates that libxl_physinfo has
> + * cap_assisted_x{2}apic fields, which indicates the availability of x{2}APIC
> + * hardware assisted virtualization.
> + */
> +#define LIBXL_HAVE_PHYSINFO_ASSISTED_APIC 1
> +
> +/*
>   * libxl ABI compatibility
>   *
>   * The only guarantee which libxl makes regarding ABI compatibility
> diff --git a/tools/libs/light/libxl.c b/tools/libs/light/libxl.c
> index 667ae6409b..fabb474221 100644
> --- a/tools/libs/light/libxl.c
> +++ b/tools/libs/light/libxl.c
> @@ -15,6 +15,7 @@
>  #include "libxl_osdeps.h"
>  
>  #include "libxl_internal.h"
> +#include "libxl_arch.h"
>  
>  int libxl_ctx_alloc(libxl_ctx **pctx, int version,
>                      unsigned flags, xentoollog_logger * lg)
> @@ -410,6 +411,8 @@ int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo 
> *physinfo)
>      physinfo->cap_gnttab_v2 =
>          !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_gnttab_v2);
>  
> +    libxl__arch_get_physinfo(physinfo, &xcphysinfo);
> +
>      GC_FREE;
>      return 0;
>  }
> diff --git a/tools/libs/light/libxl_arch.h b/tools/libs/light/libxl_arch.h
> index 1522ecb97f..207ceac6a1 100644
> --- a/tools/libs/light/libxl_arch.h
> +++ b/tools/libs/light/libxl_arch.h
> @@ -86,6 +86,10 @@ int libxl__arch_extra_memory(libxl__gc *gc,
>                               uint64_t *out);
>  
>  _hidden
> +void libxl__arch_get_physinfo(libxl_physinfo *physinfo,
> +                              const xc_physinfo_t *xcphysinfo);
> +
> +_hidden
>  void libxl__arch_update_domain_config(libxl__gc *gc,
>                                        libxl_domain_config *dst,
>                                        const libxl_domain_config *src);
> diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
> index eef1de0939..39fdca1b49 100644
> --- a/tools/libs/light/libxl_arm.c
> +++ b/tools/libs/light/libxl_arm.c
> @@ -1431,6 +1431,11 @@ int libxl__arch_passthrough_mode_setdefault(libxl__gc 
> *gc,
>      return rc;
>  }
>  
> +void libxl__arch_get_physinfo(libxl_physinfo *physinfo,
> +                              const xc_physinfo_t *xcphysinfo)
> +{
> +}
> +
>  void libxl__arch_update_domain_config(libxl__gc *gc,
>                                        libxl_domain_config *dst,
>                                        const libxl_domain_config *src)
> diff --git a/tools/libs/light/libxl_types.idl 
> b/tools/libs/light/libxl_types.idl
> index 2a42da2f7d..42ac6c357b 100644
> --- a/tools/libs/light/libxl_types.idl
> +++ b/tools/libs/light/libxl_types.idl
> @@ -1068,6 +1068,8 @@ libxl_physinfo = Struct("physinfo", [
>      ("cap_vpmu", bool),
>      ("cap_gnttab_v1", bool),
>      ("cap_gnttab_v2", bool),
> +    ("cap_assisted_xapic", bool),
> +    ("cap_assisted_x2apic", bool),
>      ], dir=DIR_OUT)
>  
>  libxl_connectorinfo = Struct("connectorinfo", [
> diff --git a/tools/libs/light/libxl_x86.c b/tools/libs/light/libxl_x86.c
> index 1feadebb18..e0a06ecfe3 100644
> --- a/tools/libs/light/libxl_x86.c
> +++ b/tools/libs/light/libxl_x86.c
> @@ -866,6 +866,17 @@ int libxl__arch_passthrough_mode_setdefault(libxl__gc 
> *gc,
>      return rc;
>  }
>  
> +void libxl__arch_get_physinfo(libxl_physinfo *physinfo,
> +                              const xc_physinfo_t *xcphysinfo)
> +{
> +    physinfo->cap_assisted_xapic =
> +        !!(xcphysinfo->arch_capabilities &
> +           XEN_SYSCTL_PHYSCAP_X86_ASSISTED_XAPIC);
> +    physinfo->cap_assisted_x2apic =
> +        !!(xcphysinfo->arch_capabilities &
> +           XEN_SYSCTL_PHYSCAP_X86_ASSISTED_X2APIC);
> +}
> +
>  void libxl__arch_update_domain_config(libxl__gc *gc,
>                                        libxl_domain_config *dst,
>                                        const libxl_domain_config *src)
> diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
> index 7503031d8f..7ce832d605 100644
> --- a/tools/ocaml/libs/xc/xenctrl.ml
> +++ b/tools/ocaml/libs/xc/xenctrl.ml
> @@ -127,6 +127,10 @@ type physinfo_cap_flag =
>       | CAP_Gnttab_v1
>       | CAP_Gnttab_v2
>  
> +type physinfo_cap_arch_flag =
> +     | CAP_ARCH_ASSISTED_XAPIC
> +     | CAP_ARCH_ASSISTED_X2APIC
> +
>  type physinfo =
>  {
>       threads_per_core : int;
> @@ -139,6 +143,7 @@ type physinfo =
>       scrub_pages      : nativeint;
>       (* XXX hw_cap *)
>       capabilities     : physinfo_cap_flag list;
> +     arch_capabilities : physinfo_cap_arch_flag list;

I know very little about Ocaml, but I think you are not setting this
field anywhere? I would expect a call to ocaml_list_to_c_bitmap and
then you will likely need to define XEN_SYSCTL_PHYSCAP_X86_MAX so you
can check the options. See XEN_SYSCTL_PHYSCAP_MAX for example.

>       max_nr_cpus      : int;
>  }
>  
> diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
> index d1d9c9247a..a2b15130ee 100644
> --- a/tools/ocaml/libs/xc/xenctrl.mli
> +++ b/tools/ocaml/libs/xc/xenctrl.mli
> @@ -112,6 +112,10 @@ type physinfo_cap_flag =
>    | CAP_Gnttab_v1
>    | CAP_Gnttab_v2
>  
> +type physinfo_cap_arch_flag =
> +  | CAP_ARCH_ASSISTED_XAPIC
> +  | CAP_ARCH_ASSISTED_X2APIC
> +
>  type physinfo = {
>    threads_per_core : int;
>    cores_per_socket : int;
> @@ -122,6 +126,7 @@ type physinfo = {
>    free_pages       : nativeint;
>    scrub_pages      : nativeint;
>    capabilities     : physinfo_cap_flag list;
> +  arch_capabilities : physinfo_cap_arch_flag list;
>    max_nr_cpus      : int; (** compile-time max possible number of nr_cpus *)
>  }
>  type version = { major : int; minor : int; extra : string; }
> diff --git a/tools/xl/xl_info.c b/tools/xl/xl_info.c
> index 712b7638b0..3205270754 100644
> --- a/tools/xl/xl_info.c
> +++ b/tools/xl/xl_info.c
> @@ -210,7 +210,7 @@ static void output_physinfo(void)
>           info.hw_cap[4], info.hw_cap[5], info.hw_cap[6], info.hw_cap[7]
>          );
>  
> -    maybe_printf("virt_caps              :%s%s%s%s%s%s%s%s%s%s%s\n",
> +    maybe_printf("virt_caps              :%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
>           info.cap_pv ? " pv" : "",
>           info.cap_hvm ? " hvm" : "",
>           info.cap_hvm && info.cap_hvm_directio ? " hvm_directio" : "",
> @@ -221,7 +221,9 @@ static void output_physinfo(void)
>           info.cap_vmtrace ? " vmtrace" : "",
>           info.cap_vpmu ? " vpmu" : "",
>           info.cap_gnttab_v1 ? " gnttab-v1" : "",
> -         info.cap_gnttab_v2 ? " gnttab-v2" : ""
> +         info.cap_gnttab_v2 ? " gnttab-v2" : "",
> +         info.cap_assisted_xapic ? " assisted_xapic" : "",
> +         info.cap_assisted_x2apic ? " assisted_x2apic" : ""
>          );
>  
>      vinfo = libxl_get_version_info(ctx);
> diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
> index 7ab15e07a0..4060aef1bd 100644
> --- a/xen/arch/x86/hvm/vmx/vmcs.c
> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
> @@ -343,6 +343,15 @@ static int vmx_init_vmcs_config(bool bsp)
>              MSR_IA32_VMX_PROCBASED_CTLS2, &mismatch);
>      }
>  
> +    /* Check whether hardware supports accelerated xapic and x2apic. */
> +    if ( bsp )
> +    {
> +        assisted_xapic_available = cpu_has_vmx_virtualize_apic_accesses;
> +        assisted_x2apic_available = (cpu_has_vmx_apic_reg_virt ||
> +                                     cpu_has_vmx_virtual_intr_delivery) &&
> +                                    cpu_has_vmx_virtualize_x2apic_mode;
> +    }
> +
>      /* The IA32_VMX_EPT_VPID_CAP MSR exists only when EPT or VPID available 
> */
>      if ( _vmx_secondary_exec_control & (SECONDARY_EXEC_ENABLE_EPT |
>                                          SECONDARY_EXEC_ENABLE_VPID) )
> diff --git a/xen/arch/x86/include/asm/domain.h 
> b/xen/arch/x86/include/asm/domain.h
> index e62e109598..72431df26d 100644
> --- a/xen/arch/x86/include/asm/domain.h
> +++ b/xen/arch/x86/include/asm/domain.h
> @@ -756,6 +756,9 @@ static inline void pv_inject_sw_interrupt(unsigned int 
> vector)
>                        : is_pv_32bit_domain(d) ? PV32_VM_ASSIST_MASK \
>                                                : PV64_VM_ASSIST_MASK)
>  
> +extern bool assisted_xapic_available;
> +extern bool assisted_x2apic_available;
> +
>  #endif /* __ASM_DOMAIN_H__ */
>  
>  /*
> diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
> index aff52a13f3..642cc96985 100644
> --- a/xen/arch/x86/sysctl.c
> +++ b/xen/arch/x86/sysctl.c
> @@ -69,6 +69,9 @@ struct l3_cache_info {
>      unsigned long size;
>  };
>  
> +bool __ro_after_init assisted_xapic_available;
> +bool __ro_after_init assisted_x2apic_available;

You could likely shorten this by dropping the _available suffix.

Thanks, Roger.