FastABI is a alternative ABI designed with performance and coco-enabled
guest in mind. It is register-oriented instead of refering to C structures
in the guest memory (through a virtual memory pointer).
It only focuses on kernel-side hypercalls, it doesn't aim to provide toolstack
operations.
Signed-off-by: Teddy Astie <teddy.as...@vates.tech>
---
docs/guest-guide/x86/fastabi.pandoc | 50 ++++++++++
docs/guest-guide/x86/index.rst | 1 +
xen/abi/event_channel.yml | 130 ++++++++++++++++++++++++++
xen/abi/grant_table.yml | 46 +++++++++
xen/abi/hvm.yml | 50 ++++++++++
xen/abi/memory.yml | 11 +++
xen/abi/sched.yml | 48 ++++++++++
xen/abi/vcpu.yml | 139 ++++++++++++++++++++++++++++
xen/abi/version.yml | 15 +++
xen/include/public/arch-x86/cpuid.h | 4 +
10 files changed, 494 insertions(+)
create mode 100644 docs/guest-guide/x86/fastabi.pandoc
create mode 100644 xen/abi/event_channel.yml
create mode 100644 xen/abi/grant_table.yml
create mode 100644 xen/abi/hvm.yml
create mode 100644 xen/abi/memory.yml
create mode 100644 xen/abi/sched.yml
create mode 100644 xen/abi/vcpu.yml
create mode 100644 xen/abi/version.yml
diff --git a/docs/guest-guide/x86/fastabi.pandoc
b/docs/guest-guide/x86/fastabi.pandoc
new file mode 100644
index 0000000000..8ff8609f37
--- /dev/null
+++ b/docs/guest-guide/x86/fastabi.pandoc
@@ -0,0 +1,50 @@
+# x86 FastABI
+
+## Introduction
+
+FastABI is a alternative hypercall ABI designed with performance and
confidential
+computing enabled guests (AMD SEV, Intel TDX, ...) in mind. It provides a
minimal
+subset of the traditional ABI that is sufficient for having a working guest.
+
+This hypercall interface is designed around using registers for passing
hypercall
+parameters and outputs rather than using pointer to C structures, thus it
avoids
+potentially complicated or expensive memory copies from/to the guest.
+
+This ABI currently only supports HVM/PVH and x86 long mode.
+
+Each hypercall operation interface is described in a parsable yaml file, which
+defines each hypercall suboperation inputs and outputs and eventual metadata
for
+code generation (e.g C stubs).
+
+## Support
+
+This interface is only supported if XEN_HVM_CPUID_FASTABI is set.
+
+## Semantics
+
+8 registers can be used as either input or output.
+
+Each hypercall operation (or sub-operation) defines its own set of used input
and
+output registers. There is no implicit clobbering of unused registers, i.e
input
+registers are not allowed to be modified by the hypervisor unless it is
explicitely
+also marked as a output (or cloberred register).
+
+- reg0: `rax`: IN: hypercall operation index, OUT: error code
+- reg1: `rdi`: (if operation has sub-operations) IN: hypercall sub-operation
index
+- reg2: `rsi`
+- reg3: `r8`
+- reg4: `r9`
+- reg5: `r10`
+- reg6: `r11`
+- reg7: `r12`
+
+`reg0` input is reserved for hypercall index.
+In order to distinguish FastABI with traditional hypercalls or viridian
hypercalls,
+reg0 input needs to be OR-ed with 0x40000000 (__HYPERVISOR_FASTABI_MASK).
+
+`reg0` output is reserved for standard hypercall return code (errno) or
returned value.
+
+`reg1` input can be used for identifying a sub-operation. output is available
for use.
+
+The hypercall uses the native hypercall instruction, which is `vmcall` on
Intel platforms
+and `vmmcall` on AMD platforms.
\ No newline at end of file
diff --git a/docs/guest-guide/x86/index.rst b/docs/guest-guide/x86/index.rst
index 6927271e53..aaae42da5a 100644
--- a/docs/guest-guide/x86/index.rst
+++ b/docs/guest-guide/x86/index.rst
@@ -7,4 +7,5 @@ x86
:maxdepth: 2
hypercall-abi
+ fastabi
fixed-memory-layout
diff --git a/xen/abi/event_channel.yml b/xen/abi/event_channel.yml
new file mode 100644
index 0000000000..44a769cdbb
--- /dev/null
+++ b/xen/abi/event_channel.yml
@@ -0,0 +1,130 @@
+name: event_channel
+hypercall_index: 32
+
+subops:
+ alloc_unbound:
+ index: 6
+ input:
+ dom: 2
+ remote_dom: 3
+ output:
+ port: 4
+ c_lang:
+ struct: evtchn_alloc_unbound
+
+ bind_interdomain:
+ index: 0
+ input:
+ remote_dom: 2
+ remote_port: 3
+ output:
+ local_port: 4
+ c_lang:
+ struct: evtchn_bind_interdomain
+
+ bind_virq:
+ index: 1
+ input:
+ virq: 2
+ vcpu: 3
+ output:
+ port: 4
+ c_lang:
+ struct: evtchn_bind_virq
+
+ bind_ipi:
+ index: 7
+ input:
+ vcpu: 2
+ output:
+ port: 4
+ c_lang:
+ struct: evtchn_bind_ipi
+
+ bind_pirq:
+ index: 2
+ input:
+ pirq: 2
+ flags: 3
+ output:
+ port: 4
+ c_lang:
+ struct: evtchn_bind_pirq
+
+ close:
+ index: 3
+ input:
+ port: 2
+ c_lang:
+ struct: evtchn_close
+
+ send:
+ index: 4
+ input:
+ port: 2
+ c_lang:
+ struct: evtchn_send
+
+ status:
+ index: 5
+ input:
+ dom: 2
+ port: 3
+ output:
+ status: 4
+ vcpu: 5
+ output1: 6
+ output2: 7
+ c_lang:
+ struct: evtchn_status
+ mapping:
+ output1: u._output1
+ output2: u._output2
+
+ bind_vcpu:
+ index: 8
+ input:
+ vcpu: 2
+ port: 3
+ c_lang:
+ struct: evtchn_bind_vcpu
+
+ unmask:
+ index: 9
+ input:
+ port: 2
+ c_lang:
+ struct: evtchn_unmask
+
+ reset:
+ index: 10
+ input:
+ dom: 2
+ c_lang:
+ struct: evtchn_reset
+
+ init_control:
+ index: 11
+ input:
+ control_gfn: 2
+ offset: 3
+ vcpu: 4
+ output:
+ link_bits: 5
+ c_lang:
+ struct: evtchn_init_control
+
+ expand_array:
+ index: 12
+ input:
+ array_gfn: 2
+ c_lang:
+ struct: evtchn_expand_array
+
+ set_priority:
+ index: 13
+ input:
+ port: 2
+ priority: 3
+ c_lang:
+ struct: evtchn_set_priority
diff --git a/xen/abi/grant_table.yml b/xen/abi/grant_table.yml
new file mode 100644
index 0000000000..bcedaa966b
--- /dev/null
+++ b/xen/abi/grant_table.yml
@@ -0,0 +1,46 @@
+name: grant_table
+hypercall_index: 20
+
+subops:
+ map_grant_ref:
+ index: 0
+ input:
+ dom: 2
+ host_addr: 3
+ flags: 4
+ ref: 5
+ output:
+ handle: 6
+ status: 7
+ c_lang:
+ struct: gnttab_map_grant_ref
+
+ unmap_grant_ref:
+ index: 1
+ input:
+ host_addr: 3
+ handle: 6
+ c_lang:
+ struct: gnttab_unmap_grant_ref
+
+ query_size:
+ index: 6
+ output:
+ nr_frames: 2
+ max_nr_frames: 3
+ c_lang:
+ struct: gnttab_query_size
+
+ set_version:
+ index: 8
+ input:
+ version: 2
+ c_lang:
+ struct: gnttab_set_version
+
+ get_version:
+ index: 10
+ output:
+ version: 2
+ c_lang:
+ struct: gnttab_get_version
diff --git a/xen/abi/hvm.yml b/xen/abi/hvm.yml
new file mode 100644
index 0000000000..20c2421bdf
--- /dev/null
+++ b/xen/abi/hvm.yml
@@ -0,0 +1,50 @@
+name: hvm
+hypercall_index: 34
+
+subops:
+ set_param:
+ index: 0
+ input:
+ domid: 2
+ index: 3
+ value: 4
+ c_lang:
+ struct: xen_hvm_param
+
+ get_param:
+ index: 1
+ input:
+ domid: 2
+ index: 3
+ output:
+ value: 4
+ c_lang:
+ struct: xen_hvm_param
+
+ flush_tlbs:
+ index: 5
+
+ get_time:
+ index: 10
+ output:
+ now: 2
+ c_lang:
+ struct: xen_hvm_get_time
+
+ get_mem_type:
+ index: 15
+ input:
+ domid: 2
+ pfn: 3
+ output:
+ mem_type: 4
+ c_lang:
+ struct: xen_hvm_get_mem_type
+
+ set_evtchn_upcall_vector:
+ index: 23
+ input:
+ vcpu: 2
+ vector: 3
+ c_lang:
+ struct: xen_hvm_evtchn_upcall_vector
diff --git a/xen/abi/memory.yml b/xen/abi/memory.yml
new file mode 100644
index 0000000000..8b51490f8a
--- /dev/null
+++ b/xen/abi/memory.yml
@@ -0,0 +1,11 @@
+name: memory
+hypercall_index: 12
+
+subops:
+ memory_map:
+ index: 9
+ input:
+ nr_entries: 2
+ buffer: 3
+ c_lang:
+ struct: xen_memory_map
diff --git a/xen/abi/sched.yml b/xen/abi/sched.yml
new file mode 100644
index 0000000000..1b1ef50c7a
--- /dev/null
+++ b/xen/abi/sched.yml
@@ -0,0 +1,48 @@
+name: sched
+hypercall_index: 29
+
+subops:
+ yield:
+ index: 0
+
+ block:
+ index: 1
+
+ shutdown:
+ index: 2
+ input:
+ reason: 2
+ c_lang:
+ struct: sched_shutdown
+
+ poll:
+ index: 3
+ input:
+ timeout: 2
+ port: 3
+ c_lang:
+ params:
+ timeout: uint64_t
+ port: evtchn_port_t
+
+ shutdown_code:
+ index: 5
+ input:
+ reason: 2
+ c_lang:
+ struct: sched_shutdown
+
+ watchdog:
+ index: 6
+ input:
+ id: 2
+ timeout: 3
+ c_lang:
+ struct: sched_watchdog
+
+ pin_override:
+ index: 7
+ input:
+ pcpu: 2
+ c_lang:
+ struct: sched_pin_override
diff --git a/xen/abi/vcpu.yml b/xen/abi/vcpu.yml
new file mode 100644
index 0000000000..0b4fe4ea1f
--- /dev/null
+++ b/xen/abi/vcpu.yml
@@ -0,0 +1,139 @@
+name: vcpu
+hypercall_index: 24
+
+subops:
+ initialise:
+ index: 0
+ input:
+ vcpuid: 2
+ context_gfn: 3
+ c_lang:
+ params:
+ vcpuid: uint32_t
+ context_gfn: uint64_t
+
+ up:
+ index: 1
+ input:
+ vcpuid: 2
+ c_lang:
+ params:
+ vcpuid: uint32_t
+
+ down:
+ index: 2
+ input:
+ vcpuid: 2
+ c_lang:
+ params:
+ vcpuid: uint32_t
+
+ is_up:
+ index: 3
+ input:
+ vcpuid: 2
+ c_lang:
+ params:
+ vcpuid: uint32_t
+
+ get_runstate_info:
+ index: 4
+ input:
+ vcpuid: 2
+ output:
+ state: 2
+ state_entry_time: 3
+ time[0]: 4
+ time[1]: 5
+ time[2]: 6
+ time[3]: 7
+ c_lang:
+ struct: vcpu_runstate_info
+ params:
+ vcpuid: uint32_t
+
+ register_runstate_phys_area:
+ index: 14
+ input:
+ vcpuid: 2
+ addr.p: 3
+ c_lang:
+ struct: vcpu_register_time_memory_area
+ params:
+ vcpuid: uint32_t
+
+ set_periodic_timer:
+ index: 6
+ input:
+ vcpuid: 2
+ period_ns: 3
+ c_lang:
+ struct: vcpu_set_periodic_timer
+ params:
+ vcpuid: uint32_t
+
+ stop_periodic_timer:
+ index: 7
+ input:
+ vcpuid: 2
+ c_lang:
+ params:
+ vcpuid: uint32_t
+
+ set_singleshot_timer:
+ index: 8
+ input:
+ vcpuid: 2
+ timeout_abs_ns: 3
+ flags: 4
+ c_lang:
+ struct: vcpu_set_singleshot_timer
+ params:
+ vcpuid: uint32_t
+
+ stop_singleshot_timer:
+ index: 9
+ input:
+ vcpuid: 2
+ c_lang:
+ params:
+ vcpuid: uint32_t
+
+ register_vcpu_info:
+ index: 10
+ input:
+ vcpuid: 2
+ mfn: 3
+ offset: 4
+ c_lang:
+ struct: vcpu_register_vcpu_info
+ params:
+ vcpuid: uint32_t
+
+ send_nmi:
+ index: 11
+ input:
+ vcpuid: 2
+ c_lang:
+ params:
+ vcpuid: uint32_t
+
+ get_physid:
+ index: 12
+ input:
+ vcpuid: 2
+ phys_id: 3
+ c_lang:
+ struct: vcpu_get_physid
+ params:
+ vcpuid: uint32_t
+
+ register_vcpu_time_phys_area:
+ index: 15
+ input:
+ vcpuid: 2
+ addr.p: 3
+ c_lang:
+ struct: vcpu_register_time_memory_area
+ params:
+ vcpuid: uint32_t
diff --git a/xen/abi/version.yml b/xen/abi/version.yml
new file mode 100644
index 0000000000..bce64a4d69
--- /dev/null
+++ b/xen/abi/version.yml
@@ -0,0 +1,15 @@
+name: version
+hypercall_index: 17
+
+subops:
+ version:
+ index: 0
+
+ get_features:
+ index: 6
+ input:
+ submap_idx: 2
+ output:
+ submap: 3
+ c_lang:
+ struct: xen_feature_info
diff --git a/xen/include/public/arch-x86/cpuid.h
b/xen/include/public/arch-x86/cpuid.h
index 3bb0dd249f..ff44ce0e7b 100644
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -106,6 +106,10 @@
* bound to event channels.
*/
#define XEN_HVM_CPUID_UPCALL_VECTOR (1u << 6)
+/*
+ * Support for fast HVM ABI.
+ */
+#define XEN_HVM_CPUID_FASTABI (1u << 7)
/*
* Leaf 6 (0x40000x05)
--
2.50.1
Teddy Astie | Vates XCP-ng Developer
XCP-ng & Xen Orchestra - Vates solutions
web: https://vates.tech
