KVM: arm64: Propagate and use kvm_s2_fault_result on S2 fault

When stage 2 page tables fault the net result may either be that a page is
mapped, an error occurred or the fault should be retried (-EAGAIN).

When a fault succeeds it may be upgraded to a PMD size via
transparent_hugepage_adjust().

In order to support KVM pre-faulting the outcome of the fault and the
mapping size must be recorded.

Track the mapping size via new kvm_s2_fault_result struct, which is
threaded through gmem_abort(), user_mem_abort() and kvm_s2_fault_map().

PKVM and SEA aren't relevant to synthetic pre-faulting so neither
kvm_inject_sea() nor pkvm_mem_abort() are altered.

Actual hardware faulting doesn't require this information, so
kvm_handle_guest_abort() simply passes NULL kvm_s2_fault_result to
gmem_abort() and user_mem_abort().

A non-NULL result also tells the abort handlers that the caller is
pre-faulting rather than a vcpu, in which case -EAGAIN is propagated to the
caller to allow the pre-fault to be retried.

Likewise, only prepare a KVM_EXIT_MEMORY_FAULT in gmem_abort() when a real
fault is being handled, as this updates vcpu state.

No functional change intended.

Suggested-by: Vincent Donnefort <vdonnefort@google.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev>
Tested-by: Fuad Tabba <fuad.tabba@linux.dev>
Link: https://patch.msgid.link/20260923-kvm-arm-prefault-v4-6-d4b0b4dfa8c3@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

0 files changed, 0 insertions, 0 deletions