ARM: KVM: arch_timers: Add timer world switch
Do the necessary save/restore dance for the timers in the world
switch code. In the process, allow the guest to read the physical
counter, which is useful for its own clock_event_device.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
index 06f2513..3c8f2f0 100644
--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -300,6 +300,14 @@
str r11, [vcpu, #CP15_OFFSET(c6_IFAR)]
str r12, [vcpu, #CP15_OFFSET(c12_VBAR)]
.endif
+
+ mrc p15, 0, r2, c14, c1, 0 @ CNTKCTL
+
+ .if \store_to_vcpu == 0
+ push {r2}
+ .else
+ str r2, [vcpu, #CP15_OFFSET(c14_CNTKCTL)]
+ .endif
.endm
/*
@@ -311,6 +319,14 @@
*/
.macro write_cp15_state read_from_vcpu
.if \read_from_vcpu == 0
+ pop {r2}
+ .else
+ ldr r2, [vcpu, #CP15_OFFSET(c14_CNTKCTL)]
+ .endif
+
+ mcr p15, 0, r2, c14, c1, 0 @ CNTKCTL
+
+ .if \read_from_vcpu == 0
pop {r2-r12}
.else
ldr r2, [vcpu, #CP15_OFFSET(c13_CID)]
@@ -461,8 +477,28 @@
* for the host.
*
* Assumes vcpu pointer in vcpu reg
+ * Clobbers r2-r5
*/
.macro save_timer_state
+#ifdef CONFIG_KVM_ARM_TIMER
+ ldr r4, [vcpu, #VCPU_KVM]
+ ldr r2, [r4, #KVM_TIMER_ENABLED]
+ cmp r2, #0
+ beq 1f
+
+ mrc p15, 0, r2, c14, c3, 1 @ CNTV_CTL
+ str r2, [vcpu, #VCPU_TIMER_CNTV_CTL]
+ bic r2, #1 @ Clear ENABLE
+ mcr p15, 0, r2, c14, c3, 1 @ CNTV_CTL
+ isb
+
+ mrrc p15, 3, r2, r3, c14 @ CNTV_CVAL
+ ldr r4, =VCPU_TIMER_CNTV_CVAL
+ add r5, vcpu, r4
+ strd r2, r3, [r5]
+
+1:
+#endif
@ Allow physical timer/counter access for the host
mrc p15, 4, r2, c14, c1, 0 @ CNTHCTL
orr r2, r2, #(CNTHCTL_PL1PCEN | CNTHCTL_PL1PCTEN)
@@ -474,6 +510,7 @@
* for the host.
*
* Assumes vcpu pointer in vcpu reg
+ * Clobbers r2-r5
*/
.macro restore_timer_state
@ Disallow physical timer access for the guest
@@ -482,6 +519,28 @@
orr r2, r2, #CNTHCTL_PL1PCTEN
bic r2, r2, #CNTHCTL_PL1PCEN
mcr p15, 4, r2, c14, c1, 0 @ CNTHCTL
+
+#ifdef CONFIG_KVM_ARM_TIMER
+ ldr r4, [vcpu, #VCPU_KVM]
+ ldr r2, [r4, #KVM_TIMER_ENABLED]
+ cmp r2, #0
+ beq 1f
+
+ ldr r2, [r4, #KVM_TIMER_CNTVOFF]
+ ldr r3, [r4, #(KVM_TIMER_CNTVOFF + 4)]
+ mcrr p15, 4, r2, r3, c14 @ CNTVOFF
+
+ ldr r4, =VCPU_TIMER_CNTV_CVAL
+ add r5, vcpu, r4
+ ldrd r2, r3, [r5]
+ mcrr p15, 3, r2, r3, c14 @ CNTV_CVAL
+ isb
+
+ ldr r2, [vcpu, #VCPU_TIMER_CNTV_CTL]
+ and r2, r2, #3
+ mcr p15, 0, r2, c14, c3, 1 @ CNTV_CTL
+1:
+#endif
.endm
.equ vmentry, 0