diff mbox series

[v6,2/2] x86/xen: Allow per-domain usage of hardware virtualized APIC

Message ID 20220308173643.2929-1-jane.malalane@citrix.com (mailing list archive)
State Superseded
Headers show
Series [v6,1/2] xen+tools: Report Interrupt Controller Virtualization capabilities on x86 | expand

Commit Message

Jane Malalane March 8, 2022, 5:36 p.m. UTC
Introduce a new per-domain creation x86 specific flag to
select whether hardware assisted virtualization should be used for
x{2}APIC.

A per-domain option is added to xl in order to select the usage of
x{2}APIC hardware assisted virtualization, as well as a global
configuration option.

Having all APIC interaction exit to Xen for emulation is slow and can
induce much overhead. Hardware can speed up x{2}APIC by decoding the
APIC access and providing a VM exit with a more specific exit reason
than a regular EPT fault or by altogether avoiding a VM exit.

On the other hand, being able to disable x{2}APIC hardware assisted
virtualization can be useful for testing and debugging purposes.

Note: vmx_install_vlapic_mapping doesn't require modifications
regardless of whether the guest has "Virtualize APIC accesses" enabled
or not, i.e., setting the APIC_ACCESS_ADDR VMCS field is fine so long
as virtualize_apic_accesses is supported by the CPU.

Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jane Malalane <jane.malalane@citrix.com>
---
CC: Wei Liu <wl@xen.org>
CC: Anthony PERARD <anthony.perard@citrix.com>
CC: Juergen Gross <jgross@suse.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: George Dunlap <george.dunlap@citrix.com>
CC: Jan Beulich <jbeulich@suse.com>
CC: Julien Grall <julien@xen.org>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Christian Lindig <christian.lindig@citrix.com>
CC: David Scott <dave@recoil.org>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
CC: "Roger Pau Monné" <roger.pau@citrix.com>

v6:
 * Use ENODEV instead of EINVAL when rejecting assisted_x{2}apic
   for PV guests
 * Move has_assisted_x{2}apic macros out of an Intel specific header
 * Remove references to Intel specific features in documentation

v5:
 * Revert v4 changes in vmx_vlapic_msr_changed(), preserving the use of
   the has_assisted_x{2}apic macros
 * Following changes in assisted_x{2}apic_available definitions in
   patch 1, retighten conditionals for setting
   XEN_HVM_CPUID_APIC_ACCESS_VIRT and XEN_HVM_CPUID_X2APIC_VIRT in
   cpuid_hypervisor_leaves()

v4:
 * Add has_assisted_x{2}apic macros and use them where appropriate
 * Replace CPU checks with per-domain assisted_x{2}apic control
   options in vmx_vlapic_msr_changed() and cpuid_hypervisor_leaves(),
   following edits to assisted_x{2}apic_available definitions in
   patch 1
   Note: new assisted_x{2}apic_available definitions make later
   cpu_has_vmx_apic_reg_virt and cpu_has_vmx_virtual_intr_delivery
   checks redundant in vmx_vlapic_msr_changed()

v3:
 * Change info in xl.cfg to better express reality and fix
   capitalization of x{2}apic
 * Move "physinfo" variable definition to the beggining of
   libxl__domain_build_info_setdefault()
 * Reposition brackets in if statement to match libxl coding style
 * Shorten logic in libxl__arch_domain_build_info_setdefault()
 * Correct dprintk message in arch_sanitise_domain_config()
 * Make appropriate changes in vmx_vlapic_msr_changed() and
   cpuid_hypervisor_leaves() for amended "assisted_x2apic" bit
 * Remove unneeded parantheses

v2:
 * Add a LIBXL_HAVE_ASSISTED_APIC macro
 * Pass xcpyshinfo as a pointer in libxl__arch_get_physinfo
 * Add a return statement in now "int"
   libxl__arch_domain_build_info_setdefault()
 * Preserve libxl__arch_domain_build_info_setdefault 's location in
   libxl_create.c
 * Correct x{2}apic default setting logic in
   libxl__arch_domain_prepare_config()
 * Correct logic for parsing assisted_x{2}apic host/guest options in
   xl_parse.c and initialize them to -1 in xl.c
 * Use guest options directly in vmx_vlapic_msr_changed
 * Fix indentation of bool assisted_x{2}apic in struct hvm_domain
 * Add a change in xenctrl_stubs.c to pass xenctrl ABI checks
---
 docs/man/xl.cfg.5.pod.in              | 15 +++++++++++++++
 docs/man/xl.conf.5.pod.in             | 12 ++++++++++++
 tools/golang/xenlight/helpers.gen.go  | 12 ++++++++++++
 tools/golang/xenlight/types.gen.go    |  2 ++
 tools/include/libxl.h                 |  7 +++++++
 tools/libs/light/libxl_arch.h         |  5 +++--
 tools/libs/light/libxl_arm.c          |  7 +++++--
 tools/libs/light/libxl_create.c       | 22 +++++++++++++---------
 tools/libs/light/libxl_types.idl      |  2 ++
 tools/libs/light/libxl_x86.c          | 27 +++++++++++++++++++++++++--
 tools/ocaml/libs/xc/xenctrl.ml        |  2 ++
 tools/ocaml/libs/xc/xenctrl.mli       |  2 ++
 tools/ocaml/libs/xc/xenctrl_stubs.c   |  2 +-
 tools/xl/xl.c                         |  8 ++++++++
 tools/xl/xl.h                         |  2 ++
 tools/xl/xl_parse.c                   | 16 ++++++++++++++++
 xen/arch/x86/domain.c                 | 28 +++++++++++++++++++++++++++-
 xen/arch/x86/hvm/vmx/vmcs.c           |  4 ++++
 xen/arch/x86/hvm/vmx/vmx.c            | 13 ++++---------
 xen/arch/x86/include/asm/hvm/domain.h |  6 ++++++
 xen/arch/x86/include/asm/hvm/hvm.h    |  6 ++++++
 xen/arch/x86/traps.c                  |  5 +++--
 xen/include/public/arch-x86/xen.h     |  2 ++
 23 files changed, 179 insertions(+), 28 deletions(-)

Comments

Roger Pau Monné March 9, 2022, 11:48 a.m. UTC | #1
On Tue, Mar 08, 2022 at 05:36:43PM +0000, Jane Malalane wrote:
> diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
> index 39fdca1b49..ba5b8f433f 100644
> --- a/tools/libs/light/libxl_arm.c
> +++ b/tools/libs/light/libxl_arm.c
> @@ -1384,8 +1384,9 @@ void libxl__arch_domain_create_info_setdefault(libxl__gc *gc,
>      }
>  }
>  
> -void libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
> -                                              libxl_domain_build_info *b_info)
> +int libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
> +                                             libxl_domain_build_info *b_info,
> +                                             const libxl_physinfo *physinfo)
>  {
>      /* ACPI is disabled by default */
>      libxl_defbool_setdefault(&b_info->acpi, false);
> @@ -1399,6 +1400,8 @@ void libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
>      memset(&b_info->u, '\0', sizeof(b_info->u));
>      b_info->type = LIBXL_DOMAIN_TYPE_INVALID;
>      libxl_domain_build_info_init_type(b_info, LIBXL_DOMAIN_TYPE_PVH);
> +
> +    return 0;

There's a void return above the memset (out of context in the diff)
that you also need to patch to 'return 0;'.


> diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
> index 77ce0b2121..7adb043ab7 100644
> --- a/xen/arch/x86/hvm/vmx/vmcs.c
> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
> @@ -1157,6 +1157,10 @@ static int construct_vmcs(struct vcpu *v)
>          __vmwrite(PLE_WINDOW, ple_window);
>      }
>  
> +    if ( !has_assisted_xapic(v->domain) )

Nit: you already have a local 'd' variable here that's v->domain, so
please use that.

> diff --git a/xen/arch/x86/include/asm/hvm/hvm.h b/xen/arch/x86/include/asm/hvm/hvm.h
> index 5b7ec0cf69..65a978f670 100644
> --- a/xen/arch/x86/include/asm/hvm/hvm.h
> +++ b/xen/arch/x86/include/asm/hvm/hvm.h
> @@ -373,6 +373,12 @@ int hvm_get_param(struct domain *d, uint32_t index, uint64_t *value);
>  #define hvm_tsc_scaling_ratio(d) \
>      ((d)->arch.hvm.tsc_scaling_ratio)
>  
> +#define has_assisted_xapic(d) \
> +    ((d)->arch.hvm.assisted_xapic)
> +
> +#define has_assisted_x2apic(d) \
> +    ((d)->arch.hvm.assisted_x2apic)

Nit: I think there's no need to split those into two lines, ie:

#define has_assisted_xapic(d) ((d)->arch.hvm.assisted_xapic)

Is well below the 80 column limit.

Thanks, Roger.
Jan Beulich March 9, 2022, 1:23 p.m. UTC | #2
On 08.03.2022 18:36, Jane Malalane wrote:
> @@ -685,13 +687,31 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
>          }
>      }
>  
> -    if ( config->arch.misc_flags & ~XEN_X86_MSR_RELAXED )
> +    if ( config->arch.misc_flags & ~(XEN_X86_MSR_RELAXED |
> +                                     XEN_X86_ASSISTED_XAPIC |
> +                                     XEN_X86_ASSISTED_X2APIC) )
>      {
>          dprintk(XENLOG_INFO, "Invalid arch misc flags %#x\n",
>                  config->arch.misc_flags);
>          return -EINVAL;
>      }
>  
> +    if ( (assisted_xapic || assisted_x2apic) && !hvm )
> +    {
> +        dprintk(XENLOG_INFO,
> +                "Interrupt Controller Virtualization not supported for PV\n");
> +        return -ENODEV;
> +    }
> +
> +    if ( (assisted_xapic && !assisted_xapic_available) ||
> +         (assisted_x2apic && !assisted_x2apic_available) )
> +    {
> +        dprintk(XENLOG_INFO,
> +                "Hardware assisted x%sAPIC requested but not available\n",
> +                assisted_xapic && !assisted_xapic_available ? "" : "2");
> +        return -EINVAL;
> +    }

My understanding of the outcome of the prior discussion was the opposite
use of EINVAL and ENODEV respectively.

Jan
Roger Pau Monné March 9, 2022, 1:51 p.m. UTC | #3
On Tue, Mar 08, 2022 at 05:36:43PM +0000, Jane Malalane wrote:
> Introduce a new per-domain creation x86 specific flag to
> select whether hardware assisted virtualization should be used for
> x{2}APIC.
> 
> A per-domain option is added to xl in order to select the usage of
> x{2}APIC hardware assisted virtualization, as well as a global
> configuration option.
> 
> Having all APIC interaction exit to Xen for emulation is slow and can
> induce much overhead. Hardware can speed up x{2}APIC by decoding the
> APIC access and providing a VM exit with a more specific exit reason
> than a regular EPT fault or by altogether avoiding a VM exit.
> 
> On the other hand, being able to disable x{2}APIC hardware assisted
> virtualization can be useful for testing and debugging purposes.
> 
> Note: vmx_install_vlapic_mapping doesn't require modifications
> regardless of whether the guest has "Virtualize APIC accesses" enabled
> or not, i.e., setting the APIC_ACCESS_ADDR VMCS field is fine so long
> as virtualize_apic_accesses is supported by the CPU.
> 
> Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Jane Malalane <jane.malalane@citrix.com>
> ---
> CC: Wei Liu <wl@xen.org>
> CC: Anthony PERARD <anthony.perard@citrix.com>
> CC: Juergen Gross <jgross@suse.com>
> CC: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: George Dunlap <george.dunlap@citrix.com>
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Julien Grall <julien@xen.org>
> CC: Stefano Stabellini <sstabellini@kernel.org>
> CC: Christian Lindig <christian.lindig@citrix.com>
> CC: David Scott <dave@recoil.org>
> CC: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
> CC: "Roger Pau Monné" <roger.pau@citrix.com>
> 
> v6:
>  * Use ENODEV instead of EINVAL when rejecting assisted_x{2}apic
>    for PV guests
>  * Move has_assisted_x{2}apic macros out of an Intel specific header
>  * Remove references to Intel specific features in documentation
> 
> v5:
>  * Revert v4 changes in vmx_vlapic_msr_changed(), preserving the use of
>    the has_assisted_x{2}apic macros
>  * Following changes in assisted_x{2}apic_available definitions in
>    patch 1, retighten conditionals for setting
>    XEN_HVM_CPUID_APIC_ACCESS_VIRT and XEN_HVM_CPUID_X2APIC_VIRT in
>    cpuid_hypervisor_leaves()
> 
> v4:
>  * Add has_assisted_x{2}apic macros and use them where appropriate
>  * Replace CPU checks with per-domain assisted_x{2}apic control
>    options in vmx_vlapic_msr_changed() and cpuid_hypervisor_leaves(),
>    following edits to assisted_x{2}apic_available definitions in
>    patch 1
>    Note: new assisted_x{2}apic_available definitions make later
>    cpu_has_vmx_apic_reg_virt and cpu_has_vmx_virtual_intr_delivery
>    checks redundant in vmx_vlapic_msr_changed()
> 
> v3:
>  * Change info in xl.cfg to better express reality and fix
>    capitalization of x{2}apic
>  * Move "physinfo" variable definition to the beggining of
>    libxl__domain_build_info_setdefault()
>  * Reposition brackets in if statement to match libxl coding style
>  * Shorten logic in libxl__arch_domain_build_info_setdefault()
>  * Correct dprintk message in arch_sanitise_domain_config()
>  * Make appropriate changes in vmx_vlapic_msr_changed() and
>    cpuid_hypervisor_leaves() for amended "assisted_x2apic" bit
>  * Remove unneeded parantheses
> 
> v2:
>  * Add a LIBXL_HAVE_ASSISTED_APIC macro
>  * Pass xcpyshinfo as a pointer in libxl__arch_get_physinfo
>  * Add a return statement in now "int"
>    libxl__arch_domain_build_info_setdefault()
>  * Preserve libxl__arch_domain_build_info_setdefault 's location in
>    libxl_create.c
>  * Correct x{2}apic default setting logic in
>    libxl__arch_domain_prepare_config()
>  * Correct logic for parsing assisted_x{2}apic host/guest options in
>    xl_parse.c and initialize them to -1 in xl.c
>  * Use guest options directly in vmx_vlapic_msr_changed
>  * Fix indentation of bool assisted_x{2}apic in struct hvm_domain
>  * Add a change in xenctrl_stubs.c to pass xenctrl ABI checks
> ---
>  docs/man/xl.cfg.5.pod.in              | 15 +++++++++++++++
>  docs/man/xl.conf.5.pod.in             | 12 ++++++++++++
>  tools/golang/xenlight/helpers.gen.go  | 12 ++++++++++++
>  tools/golang/xenlight/types.gen.go    |  2 ++
>  tools/include/libxl.h                 |  7 +++++++
>  tools/libs/light/libxl_arch.h         |  5 +++--
>  tools/libs/light/libxl_arm.c          |  7 +++++--
>  tools/libs/light/libxl_create.c       | 22 +++++++++++++---------
>  tools/libs/light/libxl_types.idl      |  2 ++
>  tools/libs/light/libxl_x86.c          | 27 +++++++++++++++++++++++++--
>  tools/ocaml/libs/xc/xenctrl.ml        |  2 ++
>  tools/ocaml/libs/xc/xenctrl.mli       |  2 ++
>  tools/ocaml/libs/xc/xenctrl_stubs.c   |  2 +-
>  tools/xl/xl.c                         |  8 ++++++++
>  tools/xl/xl.h                         |  2 ++
>  tools/xl/xl_parse.c                   | 16 ++++++++++++++++
>  xen/arch/x86/domain.c                 | 28 +++++++++++++++++++++++++++-
>  xen/arch/x86/hvm/vmx/vmcs.c           |  4 ++++
>  xen/arch/x86/hvm/vmx/vmx.c            | 13 ++++---------
>  xen/arch/x86/include/asm/hvm/domain.h |  6 ++++++
>  xen/arch/x86/include/asm/hvm/hvm.h    |  6 ++++++
>  xen/arch/x86/traps.c                  |  5 +++--
>  xen/include/public/arch-x86/xen.h     |  2 ++
>  23 files changed, 179 insertions(+), 28 deletions(-)
> 
> diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
> index b98d161398..b4239fcc5e 100644
> --- a/docs/man/xl.cfg.5.pod.in
> +++ b/docs/man/xl.cfg.5.pod.in
> @@ -1862,6 +1862,21 @@ firmware tables when using certain older guest Operating
>  Systems. These tables have been superseded by newer constructs within
>  the ACPI tables.
>  
> +=item B<assisted_xapic=BOOLEAN>
> +
> +B<(x86 only)> Enables or disables hardware assisted virtualization for
> +xAPIC. With this option enabled, a memory-mapped APIC access will be
> +decoded by hardware and either issue a more specific VM exit than just
> +an EPT fault, or altogether avoid a VM exit. The
> +default is settable via L<xl.conf(5)>.

Sorry, replied to a v2 version of the patch instead of this one. Could
we use 'p2m fault' or maybe 'guest physmap fault' intead of EPT (as
that's Intel specific).

Thanks, Roger.
diff mbox series

Patch

diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index b98d161398..b4239fcc5e 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -1862,6 +1862,21 @@  firmware tables when using certain older guest Operating
 Systems. These tables have been superseded by newer constructs within
 the ACPI tables.
 
+=item B<assisted_xapic=BOOLEAN>
+
+B<(x86 only)> Enables or disables hardware assisted virtualization for
+xAPIC. With this option enabled, a memory-mapped APIC access will be
+decoded by hardware and either issue a more specific VM exit than just
+an EPT fault, or altogether avoid a VM exit. The
+default is settable via L<xl.conf(5)>.
+
+=item B<assisted_x2apic=BOOLEAN>
+
+B<(x86 only)> Enables or disables hardware assisted virtualization for
+x2APIC. With this option enabled, certain accesses to MSR APIC
+registers will avoid a VM exit into the hypervisor. The default is
+settable via L<xl.conf(5)>.
+
 =item B<nx=BOOLEAN>
 
 B<(x86 only)> Hides or exposes the No-eXecute capability. This allows a guest
diff --git a/docs/man/xl.conf.5.pod.in b/docs/man/xl.conf.5.pod.in
index df20c08137..95d136d1ea 100644
--- a/docs/man/xl.conf.5.pod.in
+++ b/docs/man/xl.conf.5.pod.in
@@ -107,6 +107,18 @@  Sets the default value for the C<max_grant_version> domain config value.
 
 Default: maximum grant version supported by the hypervisor.
 
+=item B<assisted_xapic=BOOLEAN>
+
+If enabled, domains will use xAPIC hardware assisted virtualization by default.
+
+Default: enabled if supported.
+
+=item B<assisted_x2apic=BOOLEAN>
+
+If enabled, domains will use x2APIC hardware assisted virtualization by default.
+
+Default: enabled if supported.
+
 =item B<vif.default.script="PATH">
 
 Configures the default hotplug script used by virtual network devices.
diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go
index dd4e6c9f14..dece545ee0 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -1120,6 +1120,12 @@  x.ArchArm.Vuart = VuartType(xc.arch_arm.vuart)
 if err := x.ArchX86.MsrRelaxed.fromC(&xc.arch_x86.msr_relaxed);err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
+if err := x.ArchX86.AssistedXapic.fromC(&xc.arch_x86.assisted_xapic);err != nil {
+return fmt.Errorf("converting field ArchX86.AssistedXapic: %v", err)
+}
+if err := x.ArchX86.AssistedX2Apic.fromC(&xc.arch_x86.assisted_x2apic);err != nil {
+return fmt.Errorf("converting field ArchX86.AssistedX2Apic: %v", err)
+}
 x.Altp2M = Altp2MMode(xc.altp2m)
 x.VmtraceBufKb = int(xc.vmtrace_buf_kb)
 if err := x.Vpmu.fromC(&xc.vpmu);err != nil {
@@ -1605,6 +1611,12 @@  xc.arch_arm.vuart = C.libxl_vuart_type(x.ArchArm.Vuart)
 if err := x.ArchX86.MsrRelaxed.toC(&xc.arch_x86.msr_relaxed); err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
+if err := x.ArchX86.AssistedXapic.toC(&xc.arch_x86.assisted_xapic); err != nil {
+return fmt.Errorf("converting field ArchX86.AssistedXapic: %v", err)
+}
+if err := x.ArchX86.AssistedX2Apic.toC(&xc.arch_x86.assisted_x2apic); err != nil {
+return fmt.Errorf("converting field ArchX86.AssistedX2Apic: %v", err)
+}
 xc.altp2m = C.libxl_altp2m_mode(x.Altp2M)
 xc.vmtrace_buf_kb = C.int(x.VmtraceBufKb)
 if err := x.Vpmu.toC(&xc.vpmu); err != nil {
diff --git a/tools/golang/xenlight/types.gen.go b/tools/golang/xenlight/types.gen.go
index 87be46c745..253c9ad93d 100644
--- a/tools/golang/xenlight/types.gen.go
+++ b/tools/golang/xenlight/types.gen.go
@@ -520,6 +520,8 @@  Vuart VuartType
 }
 ArchX86 struct {
 MsrRelaxed Defbool
+AssistedXapic Defbool
+AssistedX2Apic Defbool
 }
 Altp2M Altp2MMode
 VmtraceBufKb int
diff --git a/tools/include/libxl.h b/tools/include/libxl.h
index 94e6355822..cdcccd6d01 100644
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -535,6 +535,13 @@ 
 #define LIBXL_HAVE_PHYSINFO_ASSISTED_APIC 1
 
 /*
+ * LIBXL_HAVE_ASSISTED_APIC indicates that libxl_domain_build_info has
+ * assisted_xapic and assisted_x2apic fields for enabling hardware
+ * assisted virtualization for x{2}apic per domain.
+ */
+#define LIBXL_HAVE_ASSISTED_APIC 1
+
+/*
  * libxl ABI compatibility
  *
  * The only guarantee which libxl makes regarding ABI compatibility
diff --git a/tools/libs/light/libxl_arch.h b/tools/libs/light/libxl_arch.h
index 207ceac6a1..03b89929e6 100644
--- a/tools/libs/light/libxl_arch.h
+++ b/tools/libs/light/libxl_arch.h
@@ -71,8 +71,9 @@  void libxl__arch_domain_create_info_setdefault(libxl__gc *gc,
                                                libxl_domain_create_info *c_info);
 
 _hidden
-void libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
-                                              libxl_domain_build_info *b_info);
+int libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
+                                             libxl_domain_build_info *b_info,
+                                             const libxl_physinfo *physinfo);
 
 _hidden
 int libxl__arch_passthrough_mode_setdefault(libxl__gc *gc,
diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
index 39fdca1b49..ba5b8f433f 100644
--- a/tools/libs/light/libxl_arm.c
+++ b/tools/libs/light/libxl_arm.c
@@ -1384,8 +1384,9 @@  void libxl__arch_domain_create_info_setdefault(libxl__gc *gc,
     }
 }
 
-void libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
-                                              libxl_domain_build_info *b_info)
+int libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
+                                             libxl_domain_build_info *b_info,
+                                             const libxl_physinfo *physinfo)
 {
     /* ACPI is disabled by default */
     libxl_defbool_setdefault(&b_info->acpi, false);
@@ -1399,6 +1400,8 @@  void libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
     memset(&b_info->u, '\0', sizeof(b_info->u));
     b_info->type = LIBXL_DOMAIN_TYPE_INVALID;
     libxl_domain_build_info_init_type(b_info, LIBXL_DOMAIN_TYPE_PVH);
+
+    return 0;
 }
 
 int libxl__arch_passthrough_mode_setdefault(libxl__gc *gc,
diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
index 15ed021f41..88d08d7277 100644
--- a/tools/libs/light/libxl_create.c
+++ b/tools/libs/light/libxl_create.c
@@ -75,6 +75,7 @@  int libxl__domain_build_info_setdefault(libxl__gc *gc,
                                         libxl_domain_build_info *b_info)
 {
     int i, rc;
+    libxl_physinfo info;
 
     if (b_info->type != LIBXL_DOMAIN_TYPE_HVM &&
         b_info->type != LIBXL_DOMAIN_TYPE_PV &&
@@ -264,7 +265,18 @@  int libxl__domain_build_info_setdefault(libxl__gc *gc,
     if (!b_info->event_channels)
         b_info->event_channels = 1023;
 
-    libxl__arch_domain_build_info_setdefault(gc, b_info);
+    rc = libxl_get_physinfo(CTX, &info);
+    if (rc) {
+        LOG(ERROR, "failed to get hypervisor info");
+        return rc;
+    }
+
+    rc = libxl__arch_domain_build_info_setdefault(gc, b_info, &info);
+    if (rc) {
+        LOG(ERROR, "unable to set domain arch build info defaults");
+        return rc;
+    }
+
     libxl_defbool_setdefault(&b_info->dm_restrict, false);
 
     if (b_info->iommu_memkb == LIBXL_MEMKB_DEFAULT)
@@ -457,14 +469,6 @@  int libxl__domain_build_info_setdefault(libxl__gc *gc,
     }
 
     if (b_info->max_grant_version == LIBXL_MAX_GRANT_DEFAULT) {
-        libxl_physinfo info;
-
-        rc = libxl_get_physinfo(CTX, &info);
-        if (rc) {
-            LOG(ERROR, "failed to get hypervisor info");
-            return rc;
-        }
-
         if (info.cap_gnttab_v2)
             b_info->max_grant_version = 2;
         else if (info.cap_gnttab_v1)
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index 42ac6c357b..db5eb0a0b3 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -648,6 +648,8 @@  libxl_domain_build_info = Struct("domain_build_info",[
                                ("vuart", libxl_vuart_type),
                               ])),
     ("arch_x86", Struct(None, [("msr_relaxed", libxl_defbool),
+                               ("assisted_xapic", libxl_defbool),
+                               ("assisted_x2apic", libxl_defbool),
                               ])),
     # Alternate p2m is not bound to any architecture or guest type, as it is
     # supported by x86 HVM and ARM support is planned.
diff --git a/tools/libs/light/libxl_x86.c b/tools/libs/light/libxl_x86.c
index e0a06ecfe3..c7f9f3774f 100644
--- a/tools/libs/light/libxl_x86.c
+++ b/tools/libs/light/libxl_x86.c
@@ -23,6 +23,14 @@  int libxl__arch_domain_prepare_config(libxl__gc *gc,
     if (libxl_defbool_val(d_config->b_info.arch_x86.msr_relaxed))
         config->arch.misc_flags |= XEN_X86_MSR_RELAXED;
 
+    if (d_config->c_info.type != LIBXL_DOMAIN_TYPE_PV)
+    {
+        if (libxl_defbool_val(d_config->b_info.arch_x86.assisted_xapic))
+            config->arch.misc_flags |= XEN_X86_ASSISTED_XAPIC;
+
+        if (libxl_defbool_val(d_config->b_info.arch_x86.assisted_x2apic))
+            config->arch.misc_flags |= XEN_X86_ASSISTED_X2APIC;
+    }
     return 0;
 }
 
@@ -819,11 +827,26 @@  void libxl__arch_domain_create_info_setdefault(libxl__gc *gc,
 {
 }
 
-void libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
-                                              libxl_domain_build_info *b_info)
+int libxl__arch_domain_build_info_setdefault(libxl__gc *gc,
+                                             libxl_domain_build_info *b_info,
+                                             const libxl_physinfo *physinfo)
 {
     libxl_defbool_setdefault(&b_info->acpi, true);
     libxl_defbool_setdefault(&b_info->arch_x86.msr_relaxed, false);
+
+    if (b_info->type != LIBXL_DOMAIN_TYPE_PV) {
+        libxl_defbool_setdefault(&b_info->arch_x86.assisted_xapic,
+                             physinfo->cap_assisted_xapic);
+        libxl_defbool_setdefault(&b_info->arch_x86.assisted_x2apic,
+                             physinfo->cap_assisted_x2apic);
+    }
+    else if (!libxl_defbool_is_default(b_info->arch_x86.assisted_xapic) ||
+             !libxl_defbool_is_default(b_info->arch_x86.assisted_x2apic)) {
+        LOG(ERROR, "Interrupt Controller Virtualization not supported for PV");
+        return ERROR_INVAL;
+    }
+
+    return 0;
 }
 
 int libxl__arch_passthrough_mode_setdefault(libxl__gc *gc,
diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index 712456e098..32f3028828 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -50,6 +50,8 @@  type x86_arch_emulation_flags =
 
 type x86_arch_misc_flags =
 	| X86_MSR_RELAXED
+	| X86_ASSISTED_XAPIC
+	| X86_ASSISTED_X2APIC
 
 type xen_x86_arch_domainconfig =
 {
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index b034434f68..d0fcbc8866 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -44,6 +44,8 @@  type x86_arch_emulation_flags =
 
 type x86_arch_misc_flags =
   | X86_MSR_RELAXED
+  | X86_ASSISTED_XAPIC
+  | X86_ASSISTED_X2APIC
 
 type xen_x86_arch_domainconfig = {
   emulation_flags: x86_arch_emulation_flags list;
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 7e9c32ad1b..5df8aaa58f 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -239,7 +239,7 @@  CAMLprim value stub_xc_domain_create(value xch, value wanted_domid, value config
 
 		cfg.arch.misc_flags = ocaml_list_to_c_bitmap
 			/* ! x86_arch_misc_flags X86_ none */
-			/* ! XEN_X86_ XEN_X86_MSR_RELAXED all */
+			/* ! XEN_X86_ XEN_X86_ASSISTED_X2APIC max */
 			(VAL_MISC_FLAGS);
 
 #undef VAL_MISC_FLAGS
diff --git a/tools/xl/xl.c b/tools/xl/xl.c
index 2d1ec18ea3..31eb223309 100644
--- a/tools/xl/xl.c
+++ b/tools/xl/xl.c
@@ -57,6 +57,8 @@  int max_grant_frames = -1;
 int max_maptrack_frames = -1;
 int max_grant_version = LIBXL_MAX_GRANT_DEFAULT;
 libxl_domid domid_policy = INVALID_DOMID;
+int assisted_xapic = -1;
+int assisted_x2apic = -1;
 
 xentoollog_level minmsglevel = minmsglevel_default;
 
@@ -201,6 +203,12 @@  static void parse_global_config(const char *configfile,
     if (!xlu_cfg_get_long (config, "claim_mode", &l, 0))
         claim_mode = l;
 
+    if (!xlu_cfg_get_long (config, "assisted_xapic", &l, 0))
+        assisted_xapic = l;
+
+    if (!xlu_cfg_get_long (config, "assisted_x2apic", &l, 0))
+        assisted_x2apic = l;
+
     xlu_cfg_replace_string (config, "remus.default.netbufscript",
         &default_remus_netbufscript, 0);
     xlu_cfg_replace_string (config, "colo.default.proxyscript",
diff --git a/tools/xl/xl.h b/tools/xl/xl.h
index c5c4bedbdd..528deb3feb 100644
--- a/tools/xl/xl.h
+++ b/tools/xl/xl.h
@@ -286,6 +286,8 @@  extern libxl_bitmap global_vm_affinity_mask;
 extern libxl_bitmap global_hvm_affinity_mask;
 extern libxl_bitmap global_pv_affinity_mask;
 extern libxl_domid domid_policy;
+extern int assisted_xapic;
+extern int assisted_x2apic;
 
 enum output_format {
     OUTPUT_FORMAT_JSON,
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index 117fcdcb2b..0ab9b145fe 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -1681,6 +1681,22 @@  void parse_config_data(const char *config_source,
         xlu_cfg_get_defbool(config, "vpt_align", &b_info->u.hvm.vpt_align, 0);
         xlu_cfg_get_defbool(config, "apic", &b_info->apic, 0);
 
+        e = xlu_cfg_get_long(config, "assisted_xapic", &l , 0);
+        if ((e == ESRCH && assisted_xapic != -1)) /* use global default if present */
+            libxl_defbool_set(&b_info->arch_x86.assisted_xapic, assisted_xapic);
+        else if (!e)
+            libxl_defbool_set(&b_info->arch_x86.assisted_xapic, l);
+        else
+            exit(1);
+
+        e = xlu_cfg_get_long(config, "assisted_x2apic", &l, 0);
+        if ((e == ESRCH && assisted_x2apic != -1)) /* use global default if present */
+            libxl_defbool_set(&b_info->arch_x86.assisted_x2apic, assisted_x2apic);
+        else if (!e)
+            libxl_defbool_set(&b_info->arch_x86.assisted_x2apic, l);
+        else
+            exit(1);
+
         switch (xlu_cfg_get_list(config, "viridian",
                                  &viridian, &num_viridian, 1))
         {
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index a5048ed654..b18d5c9b52 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -619,6 +619,8 @@  int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
     bool hvm = config->flags & XEN_DOMCTL_CDF_hvm;
     bool hap = config->flags & XEN_DOMCTL_CDF_hap;
     bool nested_virt = config->flags & XEN_DOMCTL_CDF_nested_virt;
+    bool assisted_xapic = config->arch.misc_flags & XEN_X86_ASSISTED_XAPIC;
+    bool assisted_x2apic = config->arch.misc_flags & XEN_X86_ASSISTED_X2APIC;
     unsigned int max_vcpus;
 
     if ( hvm ? !hvm_enabled : !IS_ENABLED(CONFIG_PV) )
@@ -685,13 +687,31 @@  int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
         }
     }
 
-    if ( config->arch.misc_flags & ~XEN_X86_MSR_RELAXED )
+    if ( config->arch.misc_flags & ~(XEN_X86_MSR_RELAXED |
+                                     XEN_X86_ASSISTED_XAPIC |
+                                     XEN_X86_ASSISTED_X2APIC) )
     {
         dprintk(XENLOG_INFO, "Invalid arch misc flags %#x\n",
                 config->arch.misc_flags);
         return -EINVAL;
     }
 
+    if ( (assisted_xapic || assisted_x2apic) && !hvm )
+    {
+        dprintk(XENLOG_INFO,
+                "Interrupt Controller Virtualization not supported for PV\n");
+        return -ENODEV;
+    }
+
+    if ( (assisted_xapic && !assisted_xapic_available) ||
+         (assisted_x2apic && !assisted_x2apic_available) )
+    {
+        dprintk(XENLOG_INFO,
+                "Hardware assisted x%sAPIC requested but not available\n",
+                assisted_xapic && !assisted_xapic_available ? "" : "2");
+        return -EINVAL;
+    }
+
     return 0;
 }
 
@@ -864,6 +884,12 @@  int arch_domain_create(struct domain *d,
 
     d->arch.msr_relaxed = config->arch.misc_flags & XEN_X86_MSR_RELAXED;
 
+    d->arch.hvm.assisted_xapic =
+        config->arch.misc_flags & XEN_X86_ASSISTED_XAPIC;
+
+    d->arch.hvm.assisted_x2apic =
+        config->arch.misc_flags & XEN_X86_ASSISTED_X2APIC;
+
     return 0;
 
  fail:
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 77ce0b2121..7adb043ab7 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1157,6 +1157,10 @@  static int construct_vmcs(struct vcpu *v)
         __vmwrite(PLE_WINDOW, ple_window);
     }
 
+    if ( !has_assisted_xapic(v->domain) )
+        v->arch.hvm.vmx.secondary_exec_control &=
+            ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+
     if ( cpu_has_vmx_secondary_exec_control )
         __vmwrite(SECONDARY_VM_EXEC_CONTROL,
                   v->arch.hvm.vmx.secondary_exec_control);
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index c075370f64..949ddd684c 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3344,16 +3344,11 @@  static void vmx_install_vlapic_mapping(struct vcpu *v)
 
 void vmx_vlapic_msr_changed(struct vcpu *v)
 {
-    int virtualize_x2apic_mode;
     struct vlapic *vlapic = vcpu_vlapic(v);
     unsigned int msr;
 
-    virtualize_x2apic_mode = ( (cpu_has_vmx_apic_reg_virt ||
-                                cpu_has_vmx_virtual_intr_delivery) &&
-                               cpu_has_vmx_virtualize_x2apic_mode );
-
-    if ( !cpu_has_vmx_virtualize_apic_accesses &&
-         !virtualize_x2apic_mode )
+    if ( !has_assisted_xapic(v->domain) &&
+         !has_assisted_x2apic(v->domain) )
         return;
 
     vmx_vmcs_enter(v);
@@ -3363,7 +3358,7 @@  void vmx_vlapic_msr_changed(struct vcpu *v)
     if ( !vlapic_hw_disabled(vlapic) &&
          (vlapic_base_address(vlapic) == APIC_DEFAULT_PHYS_BASE) )
     {
-        if ( virtualize_x2apic_mode && vlapic_x2apic_mode(vlapic) )
+        if ( has_assisted_x2apic(v->domain) && vlapic_x2apic_mode(vlapic) )
         {
             v->arch.hvm.vmx.secondary_exec_control |=
                 SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
@@ -3384,7 +3379,7 @@  void vmx_vlapic_msr_changed(struct vcpu *v)
                 vmx_clear_msr_intercept(v, MSR_X2APIC_SELF, VMX_MSR_W);
             }
         }
-        else
+        else if ( has_assisted_xapic(v->domain) )
             v->arch.hvm.vmx.secondary_exec_control |=
                 SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
     }
diff --git a/xen/arch/x86/include/asm/hvm/domain.h b/xen/arch/x86/include/asm/hvm/domain.h
index 698455444e..92bf53483c 100644
--- a/xen/arch/x86/include/asm/hvm/domain.h
+++ b/xen/arch/x86/include/asm/hvm/domain.h
@@ -117,6 +117,12 @@  struct hvm_domain {
 
     bool                   is_s3_suspended;
 
+    /* xAPIC hardware assisted virtualization. */
+    bool                   assisted_xapic;
+
+    /* x2APIC hardware assisted virtualization. */
+    bool                   assisted_x2apic;
+
     /* hypervisor intercepted msix table */
     struct list_head       msixtbl_list;
 
diff --git a/xen/arch/x86/include/asm/hvm/hvm.h b/xen/arch/x86/include/asm/hvm/hvm.h
index 5b7ec0cf69..65a978f670 100644
--- a/xen/arch/x86/include/asm/hvm/hvm.h
+++ b/xen/arch/x86/include/asm/hvm/hvm.h
@@ -373,6 +373,12 @@  int hvm_get_param(struct domain *d, uint32_t index, uint64_t *value);
 #define hvm_tsc_scaling_ratio(d) \
     ((d)->arch.hvm.tsc_scaling_ratio)
 
+#define has_assisted_xapic(d) \
+    ((d)->arch.hvm.assisted_xapic)
+
+#define has_assisted_x2apic(d) \
+    ((d)->arch.hvm.assisted_x2apic)
+
 #define hvm_get_guest_time(v) hvm_get_guest_time_fixed(v, 0)
 
 #define hvm_paging_enabled(v) \
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index a2278d9499..a8dba88916 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1121,7 +1121,8 @@  void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf,
         if ( !is_hvm_domain(d) || subleaf != 0 )
             break;
 
-        if ( cpu_has_vmx_apic_reg_virt )
+        if ( cpu_has_vmx_apic_reg_virt &&
+             has_assisted_xapic(d) )
             res->a |= XEN_HVM_CPUID_APIC_ACCESS_VIRT;
 
         /*
@@ -1130,7 +1131,7 @@  void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf,
          * and wrmsr in the guest will run without VMEXITs (see
          * vmx_vlapic_msr_changed()).
          */
-        if ( cpu_has_vmx_virtualize_x2apic_mode &&
+        if ( has_assisted_x2apic(d) &&
              cpu_has_vmx_apic_reg_virt &&
              cpu_has_vmx_virtual_intr_delivery )
             res->a |= XEN_HVM_CPUID_X2APIC_VIRT;
diff --git a/xen/include/public/arch-x86/xen.h b/xen/include/public/arch-x86/xen.h
index 7acd94c8eb..9da32c6239 100644
--- a/xen/include/public/arch-x86/xen.h
+++ b/xen/include/public/arch-x86/xen.h
@@ -317,6 +317,8 @@  struct xen_arch_domainconfig {
  * doesn't allow the guest to read or write to the underlying MSR.
  */
 #define XEN_X86_MSR_RELAXED (1u << 0)
+#define XEN_X86_ASSISTED_XAPIC (1u << 1)
+#define XEN_X86_ASSISTED_X2APIC (1u << 2)
     uint32_t misc_flags;
 };