Adds code to enable fp/simd lazy switch. On each entry check if fp/simd
registers have been switched to guest, if no set the trap flag. On trap
switch fp/simd registers and set vfp_lazy to true and disable trapping.
When the vcpu is about to be put, then context switch fp/simd registers
save guest and restore host and reset the vfp_lazy state to enable trapping
again.
Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx>
---
arch/arm/kvm/arm.c | 17 +++++++++++++++++
arch/arm/kvm/interrupts.S | 40 +++++++++++++++++++++++++++++-----------
2 files changed, 46 insertions(+), 11 deletions(-)
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index ce404a5..0acbb69 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -105,6 +105,20 @@ void kvm_arch_check_processor_compat(void *rtn)
*(int *)rtn = 0;
}
+/**
+ * kvm_switch_fp_regs() - switch guest/host VFP/SIMD registers
+ * @vcpu: pointer to vcpu structure.
+ *
+ */
+static void kvm_switch_fp_regs(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_ARM
+ if (vcpu->arch.vfp_lazy == 1) {
+ kvm_call_hyp(__kvm_restore_host_vfp_state, vcpu);
+ vcpu->arch.vfp_lazy = 0;
+ }
+#endif
+}
/**
* kvm_arch_init_vm - initializes a VM data structure
@@ -295,6 +309,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
+ /* Check if Guest accessed VFP registers */
+ kvm_switch_fp_regs(vcpu);
+
/*
* The arch-generic KVM code expects the cpu field of a vcpu to be -1
* if the vcpu is no longer assigned to a cpu. This is used for the
diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
index 900ef6d..a47acc1 100644
--- a/arch/arm/kvm/interrupts.S
+++ b/arch/arm/kvm/interrupts.S
@@ -96,6 +96,24 @@ ENTRY(__kvm_flush_vm_context)
bx lr
ENDPROC(__kvm_flush_vm_context)
+/**
+ * void __kvm_restore_host_vfp_state(struct vcpu *vcpu) - Executes a lazy
+ * fp/simd switch, saves the guest, restores host.
+ *
+ */
+ENTRY(__kvm_restore_host_vfp_state)
+ push {r3-r7}
+
+ add r7, r0, #VCPU_VFP_GUEST
+ store_vfp_state r7
+
+ add r7, r0, #VCPU_VFP_HOST
+ ldr r7, [r7]
+ restore_vfp_state r7
+
+ pop {r3-r7}
+ bx lr
+ENDPROC(__kvm_restore_host_vfp_state)
/********************************************************************
* Hypervisor world-switch code
@@ -131,7 +149,14 @@ ENTRY(__kvm_vcpu_run)
@ Trap coprocessor CRx accesses
set_hstr vmentry
+
+ ldr r1, [vcpu, #VCPU_VFP_LAZY]
+ cmp r1, #1
+ beq skip_guest_vfp_trap
+
set_hcptr vmentry, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11))
+skip_guest_vfp_trap:
+
set_hdcr vmentry
@ Write configured ID register into MIDR alias
@@ -170,22 +195,12 @@ __kvm_vcpu_return:
@ Don't trap coprocessor accesses for host kernel
set_hstr vmexit
set_hdcr vmexit
- set_hcptr vmexit, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11)), after_vfp_restore
+ set_hcptr vmexit, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11))
#ifdef CONFIG_VFPv3
- @ Switch VFP/NEON hardware state to the host's
- add r7, vcpu, #VCPU_VFP_GUEST
- store_vfp_state r7
- add r7, vcpu, #VCPU_VFP_HOST
- ldr r7, [r7]
- restore_vfp_state r7
-
-after_vfp_restore:
@ Restore FPEXC_EN which we clobbered on entry
pop {r2}
VFPFMXR FPEXC, r2
-#else
-after_vfp_restore:
#endif
@ Reset Hyp-role
@@ -485,6 +500,9 @@ switch_to_guest_vfp:
@ NEON/VFP used. Turn on VFP access.
set_hcptr vmtrap, (HCPTR_TCP(10) | HCPTR_TCP(11))
+ mov r1, #1
+ str r1, [vcpu, #VCPU_VFP_LAZY]
+
@ Switch VFP/NEON hardware state to the guest's
add r7, r0, #VCPU_VFP_HOST
ldr r7, [r7]
--
1.9.1
--
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