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Documentation: kvm: new UAPI for handling SEA

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Document the new userspace-visible features and APIs for handling
synchronous external abort (SEA)
- KVM_CAP_ARM_SEA_TO_USER: How userspace enables the new feature.
- KVM_EXIT_ARM_SEA: exit userspace gets when it needs to handle SEA
  and what userspace gets while taking the SEA.

Signed-off-by: Jiaqi Yan <jiaqiyan@google.com>
Link: https://msgid.link/20251013185903.1372553-4-jiaqiyan@google.com
[ oliver: make documentation concise, remove implementation detail ]
Signed-off-by: Oliver Upton <oupton@kernel.org>
This commit is contained in:
Jiaqi Yan
2025-10-13 18:59:03 +00:00
committed by Oliver Upton
parent feee9ef7ac
commit 4debb5e895
1 changed files with 47 additions and 0 deletions
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47
Documentation/virt/kvm/api.rst
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@@ -7286,6 +7286,41 @@ exit, even without calls to ``KVM_ENABLE_CAP`` or similar. In this case,
it will enter with output fields already valid; in the common case, the
``unknown.ret`` field of the union will be ``TDVMCALL_STATUS_SUBFUNC_UNSUPPORTED``.
Userspace need not do anything if it does not wish to support a TDVMCALL.
::
/* KVM_EXIT_ARM_SEA */
struct {
#define KVM_EXIT_ARM_SEA_FLAG_GPA_VALID (1ULL << 0)
__u64 flags;
__u64 esr;
__u64 gva;
__u64 gpa;
} arm_sea;
Used on arm64 systems. When the VM capability ``KVM_CAP_ARM_SEA_TO_USER`` is
enabled, a KVM exits to userspace if a guest access causes a synchronous
external abort (SEA) and the host APEI fails to handle the SEA.
``esr`` is set to a sanitized value of ESR_EL2 from the exception taken to KVM,
consisting of the following fields:
- ``ESR_EL2.EC``
- ``ESR_EL2.IL``
- ``ESR_EL2.FnV``
- ``ESR_EL2.EA``
- ``ESR_EL2.CM``
- ``ESR_EL2.WNR``
- ``ESR_EL2.FSC``
- ``ESR_EL2.SET`` (when FEAT_RAS is implemented for the VM)
``gva`` is set to the value of FAR_EL2 from the exception taken to KVM when
``ESR_EL2.FnV == 0``. Otherwise, the value of ``gva`` is unknown.
``gpa`` is set to the faulting IPA from the exception taken to KVM when
the ``KVM_EXIT_ARM_SEA_FLAG_GPA_VALID`` flag is set. Otherwise, the value of
``gpa`` is unknown.
::
/* Fix the size of the union. */
@@ -8703,6 +8738,18 @@ This capability indicate to the userspace whether a PFNMAP memory region
can be safely mapped as cacheable. This relies on the presence of
force write back (FWB) feature support on the hardware.
7.45 KVM_CAP_ARM_SEA_TO_USER
----------------------------
:Architecture: arm64
:Target: VM
:Parameters: none
:Returns: 0 on success, -EINVAL if unsupported.
When this capability is enabled, KVM may exit to userspace for SEAs taken to
EL2 resulting from a guest access. See ``KVM_EXIT_ARM_SEA`` for more
information.
8. Other capabilities.
======================