ARM: KVM: Add VFP lazy save/restore handler

Similar to the arm64 version, add the code that deals with VFP traps,
re-enabling VFP, save/restoring the registers and resuming the guest.

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

1 files changed, 31 insertions, 0 deletions

diff --git a/arch/arm/kvm/hyp/entry.S b/arch/arm/kvm/hyp/entry.S
index 32f79b090040..21c238871c9e 100644
--- a/arch/arm/kvm/hyp/entry.S
+++ b/arch/arm/kvm/hyp/entry.S
@@ -66,5 +66,36 @@ ENTRY(__guest_exit)
         bx      lr
 ENDPROC(__guest_exit)
 
+/*
+ * If VFPv3 support is not available, then we will not switch the VFP
+ * registers; however cp10 and cp11 accesses will still trap and fallback
+ * to the regular coprocessor emulation code, which currently will
+ * inject an undefined exception to the guest.
+ */
+#ifdef CONFIG_VFPv3
+ENTRY(__vfp_guest_restore)
+        push    {r3, r4, lr}
+
+        @ NEON/VFP used.  Turn on VFP access.
+        mrc     p15, 4, r1, c1, c1, 2           @ HCPTR
+        bic     r1, r1, #(HCPTR_TCP(10) | HCPTR_TCP(11))
+        mcr     p15, 4, r1, c1, c1, 2           @ HCPTR
+        isb
+
+        @ Switch VFP/NEON hardware state to the guest's
+        mov     r4, r0
+        ldr     r0, [r0, #VCPU_HOST_CTXT]
+        add     r0, r0, #CPU_CTXT_VFP
+        bl      __vfp_save_state
+        add     r0, r4, #(VCPU_GUEST_CTXT + CPU_CTXT_VFP)
+        bl      __vfp_restore_state
+
+        pop     {r3, r4, lr}
+        pop     {r0, r1, r2}
+        clrex
+        eret
+ENDPROC(__vfp_guest_restore)
+#endif
+
         .popsection