arm64: KVM: Only force FPEXC32_EL2.EN if trapping FPSIMD

If trapping FPSIMD in the context of an AArch32 guest, it is critical
to set FPEXC32_EL2.EN to 1 so that the trapping is taken to EL2 and
not EL1.

Conversely, it is just as critical *not* to set FPEXC32_EL2.EN to 1
if we're not going to trap FPSIMD, as we then corrupt the existing
VFP state.

Moving the call to __activate_traps_fpsimd32 to the point where we
know for sure that we are going to trap ensures that we don't set that
bit spuriously.

Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Cc: [email protected] # v4.18
Cc: Dave Martin <[email protected]>
Reported-by: Alexander Graf <[email protected]>
Tested-by: Alexander Graf <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Signed-off-by: Christoffer Dall <[email protected]>

0 files changed, 0 insertions, 0 deletions