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>

5 files changed, 74 insertions, 1 deletions

diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
index 5e06e8177784..e4956f4e23e1 100644
--- a/arch/arm/include/asm/kvm_asm.h
+++ b/arch/arm/include/asm/kvm_asm.h
@@ -45,7 +45,8 @@
 #define c13_TID_URW     23      /* Thread ID, User R/W */
 #define c13_TID_URO     24      /* Thread ID, User R/O */
 #define c13_TID_PRIV    25      /* Thread ID, Privileged */
-#define NR_CP15_REGS    26      /* Number of regs (incl. invalid) */
+#define c14_CNTKCTL     26      /* Timer Control Register (PL1) */
+#define NR_CP15_REGS    27      /* Number of regs (incl. invalid) */
 
 #define ARM_EXCEPTION_RESET       0
 #define ARM_EXCEPTION_UNDEFINED   1
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 17cea2e78d88..5ce738b43508 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -179,6 +179,12 @@ 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_CVAL,  offsetof(struct kvm_vcpu, arch.timer_cpu.cntv_cval));
+  DEFINE(KVM_TIMER_CNTVOFF,     offsetof(struct kvm, arch.timer.cntvoff));
+  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 ea7383293ed0..800b2cd804d3 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -718,6 +718,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
                         vcpu_pause(vcpu);
 
                 kvm_vgic_flush_hwstate(vcpu);
+                kvm_timer_flush_hwstate(vcpu);
 
                 local_irq_disable();
 
@@ -731,6 +732,7 @@ 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_hwstate(vcpu);
                         kvm_vgic_sync_hwstate(vcpu);
                         continue;
                 }
@@ -764,6 +766,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
                  * Back from guest
                  *************************************************************/
 
+                kvm_timer_sync_hwstate(vcpu);
                 kvm_vgic_sync_hwstate(vcpu);
 
                 ret = handle_exit(vcpu, run, ret);
diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c
index d782638c7ec0..4ea9a982269c 100644
--- a/arch/arm/kvm/coproc.c
+++ b/arch/arm/kvm/coproc.c
@@ -222,6 +222,10 @@ static const struct coproc_reg cp15_regs[] = {
                         NULL, reset_unknown, c13_TID_URO },
         { CRn(13), CRm( 0), Op1( 0), Op2( 4), is32,
                         NULL, reset_unknown, c13_TID_PRIV },
+
+        /* CNTKCTL: swapped by interrupt.S. */
+        { CRn(14), CRm( 1), Op1( 0), Op2( 0), is32,
+                        NULL, reset_val, c14_CNTKCTL, 0x00000000 },
 };
 
 /* Target specific emulation tables */
diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
index 06f251395bec..3c8f2f0b4c5e 100644
--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -300,6 +300,14 @@ vcpu	.req	r0		@ vcpu pointer always in r0
         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 @@ vcpu	.req	r0		@ vcpu pointer always in r0
  */
 .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 @@ vcpu	.req	r0		@ vcpu pointer always in r0
  * 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 @@ vcpu	.req	r0		@ vcpu pointer always in r0
  * 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 @@ vcpu	.req	r0		@ vcpu pointer always in r0
         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