arm64: KVM: VHE: Add fpsimd enabling on guest access

Despite the fact that a VHE enabled kernel runs at EL2, it uses
CPACR_EL1 to trap FPSIMD access. Add the required alternative
code to re-enable guest FPSIMD access when it has trapped to
EL2.

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index fd0fbe9b7e6a..ce9e5e5f28cf 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -130,9 +130,15 @@ ENDPROC(__guest_exit)
 ENTRY(__fpsimd_guest_restore)
         stp     x4, lr, [sp, #-16]!
 
+alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
         mrs     x2, cptr_el2
         bic     x2, x2, #CPTR_EL2_TFP
         msr     cptr_el2, x2
+alternative_else
+        mrs     x2, cpacr_el1
+        orr     x2, x2, #CPACR_EL1_FPEN
+        msr     cpacr_el1, x2
+alternative_endif
         isb
 
         mrs     x3, tpidr_el2