> From: Jane Malalane
> Sent: Wednesday, March 16, 2022 5:13 PM
>
> Add XEN_SYSCTL_PHYSCAP_X86_ASSISTED_XAPIC and
> XEN_SYSCTL_PHYSCAP_X86_ASSISTED_X2APIC to report accelerated xAPIC
> and
> x2APIC, on x86 hardware. This is so that xAPIC and x2APIC virtualization
> can subsequently be enabled on a per-domain basis.
> No such features are currently implemented on AMD hardware.
>
> HW assisted xAPIC virtualization will be reported if HW, at the
> minimum, supports virtualize_apic_accesses as this feature alone means
> that an access to the APIC page will cause an APIC-access VM exit. An
> APIC-access VM exit provides a VMM with information about the access
> causing the VM exit, unlike a regular EPT fault, thus simplifying some
> internal handling.
>
> HW assisted x2APIC virtualization will be reported if HW supports
> virtualize_x2apic_mode and, at least, either apic_reg_virt or
> virtual_intr_delivery. This also means that
> sysctl follows the conditionals in vmx_vlapic_msr_changed().
>
> For that purpose, also add an arch-specific "capabilities" parameter
> to struct xen_sysctl_physinfo.
>
> Note that this interface is intended to be compatible with AMD so that
> AVIC support can be introduced in a future patch. Unlike Intel that
> has multiple controls for APIC Virtualization, AMD has one global
> 'AVIC Enable' control bit, so fine-graining of APIC virtualization
> control cannot be done on a common interface.
>
> Suggested-by: Andrew Cooper
> Signed-off-by: Jane Malalane
Reviewed-by: Kevin Tian
btw the r-b from Roger is lost...
> ---
> CC: Wei Liu
> CC: Anthony PERARD
> CC: Juergen Gross
> CC: Andrew Cooper
> CC: George Dunlap
> CC: Jan Beulich
> CC: Julien Grall
> CC: Stefano Stabellini
> CC: Volodymyr Babchuk
> CC: Bertrand Marquis
> CC: Jun Nakajima
> CC: Kevin Tian
> CC: "Roger Pau Monné"
>
> v8:
> * Improve commit message
>
> v7:
> * Make sure assisted_x{2}apic_available evaluates to false, to ensure
>Xen builds, when !CONFIG_HVM
> * Fix coding style issues
>
> v6:
> * Limit abi check to x86
> * Fix coding style issue
>
> v5:
> * Have assisted_xapic_available solely depend on
>cpu_has_vmx_virtualize_apic_accesses and assisted_x2apic_available
>depend on cpu_has_vmx_virtualize_x2apic_mode and
>cpu_has_vmx_apic_reg_virt OR cpu_has_vmx_virtual_intr_delivery
>
> v4:
> * Fallback to the original v2/v1 conditions for setting
>assisted_xapic_available and assisted_x2apic_available so that in
>the future APIC virtualization can be exposed on AMD hardware
>since fine-graining of "AVIC" is not supported, i.e., AMD solely
>uses "AVIC Enable". This also means that sysctl mimics what's
>exposed in CPUID
>
> v3:
> * Define XEN_SYSCTL_PHYSCAP_ARCH_MAX for ABI checking and actually
>set "arch_capbilities", via a call to c_bitmap_to_ocaml_list()
> * Have assisted_x2apic_available only depend on
>cpu_has_vmx_virtualize_x2apic_mode
>
> 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 | 2 ++
> 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/ocaml/libs/xc/xenctrl_stubs.c | 15 +--
> tools/xl/xl_info.c | 6 --
> xen/arch/x86/hvm/hvm.c | 3 +++
> xen/arch/x86/hvm/vmx/vmcs.c | 9 +
> xen/arch/x86/include/asm/hvm/hvm.h | 5 +
> xen/arch/x86/sysctl.c| 4
> xen/include/public/sysctl.h | 11 ++-
> 17 files changed, 96 insertions(+), 5 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.CapVm
