KVM: arm64: Clear HCR_EL2.RW for 32-bit non-protected vCPUs

pKVM keeps its own copy of each vCPU's HCR_EL2 at EL2, initialised with
RW set unconditionally. Nothing stops userspace from creating a
non-protected AArch32 VM, and with RW set, entering one of its vCPUs is
an illegal exception return: KVM_RUN fails with KVM_EXIT_FAIL_ENTRY.

Clear RW for a vCPU that is AArch32 at EL1, when the CPU has AArch32
EL1. On a CPU without it, RW stays set and the entry still fails, rather
than EL2 switching *32_EL2 registers that are UNDEFINED there. The host
already rejects such a vCPU, but EL2 takes the vCPU's features from the
host and doesn't rely on that.

Fixes: b56680de9c648 ("KVM: arm64: Initialize trap register values in hyp in pKVM")
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Link: https://patch.msgid.link/20260929090031.3829185-3-fuad.tabba@linux.dev
Signed-off-by: Oliver Upton <oupton@kernel.org>

0 files changed, 0 insertions, 0 deletions