[PATCH 4/5] ARM: KVM: arch_timers: Add timer world switch

Christoffer Dall
2012-09-15T15:39:37Z

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.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
---
arch/arm/kernel/asm-offsets.c | 8 ++++++++
arch/arm/kvm/arm.c | 3 +++
arch/arm/kvm/interrupts.S | 41 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 52 insertions(+)

diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index b277b7a..cf0b50e 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -196,6 +196,14 @@ int main(void)
DEFINE(VGIC_CPU_APR, offsetof(struct vgic_cpu, vgic_apr));
DEFINE(VGIC_CPU_LR, offsetof(struct vgic_cpu, vgic_lr));
DEFINE(VGIC_CPU_NR_LR, offsetof(struct vgic_cpu, nr_lr));
+#ifdef CONFIG_KVM_ARM_TIMER
+ DEFINE(VCPU_TIMER_CNTV_CTL, offsetof(struct kvm_vcpu, arch.timer_cpu.cntv_ctl));
+ DEFINE(VCPU_TIMER_CNTV_CVALH, offsetof(struct kvm_vcpu, arch.timer_cpu.cntv_cval32.high));
+ DEFINE(VCPU_TIMER_CNTV_CVALL, offsetof(struct kvm_vcpu, arch.timer_cpu.cntv_cval32.low));
+ DEFINE(KVM_TIMER_CNTVOFF_H, offsetof(struct kvm, arch.timer.cntvoff32.high));
+ DEFINE(KVM_TIMER_CNTVOFF_L, offsetof(struct kvm, arch.timer.cntvoff32.low));
+ DEFINE(KVM_TIMER_ENABLED, offsetof(struct kvm, arch.timer.enabled));
+#endif
DEFINE(KVM_VGIC_VCTRL, offsetof(struct kvm, arch.vgic.vctrl_base));
#endif
DEFINE(KVM_VTTBR, offsetof(struct kvm, arch.vttbr));
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index b959863..af71560 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -644,6 +644,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
update_vttbr(vcpu->kvm);

kvm_vgic_sync_to_cpu(vcpu);
+ kvm_timer_sync_to_cpu(vcpu);

local_irq_disable();

@@ -657,6 +658,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)

if (ret <= 0 || need_new_vmid_gen(vcpu->kvm)) {
local_irq_enable();
+ kvm_timer_sync_from_cpu(vcpu);
kvm_vgic_sync_from_cpu(vcpu);
continue;
}
@@ -698,6 +700,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
* Back from guest
*************************************************************/

+ kvm_timer_sync_from_cpu(vcpu);
kvm_vgic_sync_from_cpu(vcpu);

ret = handle_exit(vcpu, run, ret);
diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
index d354bd8..cb1ab06 100644
--- a/arch/arm/kvm/interrupts.S
+++ b/arch/arm/kvm/interrupts.S
@@ -397,6 +397,25 @@ ENDPROC(__kvm_flush_vm_context)
#define CNTHCTL_PL1PCEN (1 << 1)

.macro save_timer_state vcpup
+#ifdef CONFIG_KVM_ARM_TIMER
+ ldr r4, [\vcpup, #VCPU_KVM]
+ ldr r2, [r4, #KVM_TIMER_ENABLED]
+ cmp r2, #0
+ beq 1f
+
+ mrc p15, 0, r2, c14, c3, 1 @ CNTV_CTL
+ and r2, #3
+ str r2, [\vcpup, #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
+ str r3, [\vcpup, #VCPU_TIMER_CNTV_CVALH]
+ str r2, [\vcpup, #VCPU_TIMER_CNTV_CVALL]
+
+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)
@@ -410,6 +429,28 @@ ENDPROC(__kvm_flush_vm_context)
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, [\vcpup, #VCPU_KVM]
+ ldr r2, [r4, #KVM_TIMER_ENABLED]
+ cmp r2, #0
+ beq 1f
+
+ ldr r3, [r4, #KVM_TIMER_CNTVOFF_H]
+ ldr r2, [r4, #KVM_TIMER_CNTVOFF_L]
+ mcrr p15, 4, r2, r3, c14 @ CNTVOFF
+ isb
+
+ ldr r3, [\vcpup, #VCPU_TIMER_CNTV_CVALH]
+ ldr r2, [\vcpup, #VCPU_TIMER_CNTV_CVALL]
+ mcrr p15, 3, r2, r3, c14 @ CNTV_CVAL
+
+ ldr r2, [\vcpup, #VCPU_TIMER_CNTV_CTL]
+ and r2, #3
+ mcr p15, 0, r2, c14, c3, 1 @ CNTV_CTL
+ isb
+1:
+#endif
.endm

/* Configures the HSTR (Hyp System Trap Register) on entry/return