[PATCH v2 15/28] ARM: KVM: Add VFP lazy save/restore handler

Marc Zyngier
2016-02-04T11:00:32Z

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

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm/kvm/hyp/entry.S | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/arch/arm/kvm/hyp/entry.S b/arch/arm/kvm/hyp/entry.S
index 32f79b0..21c2388 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

--
2.1.4