arm64: KVM: Plug the arch timer

Add support for the in-kernel timer emulation.

Reviewed-by: Christopher Covington <cov@codeaurora.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

2 files changed, 68 insertions, 0 deletions

diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 8dc27a367d77..8b510835b440 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -390,6 +390,60 @@ __kvm_hyp_code_start:
 2:
 .endm
 
+.macro save_timer_state
+        // x0: vcpu pointer
+        ldr     x2, [x0, #VCPU_KVM]
+        kern_hyp_va x2
+        ldr     w3, [x2, #KVM_TIMER_ENABLED]
+        cbz     w3, 1f
+
+        mrs     x3, cntv_ctl_el0
+        and     x3, x3, #3
+        str     w3, [x0, #VCPU_TIMER_CNTV_CTL]
+        bic     x3, x3, #1              // Clear Enable
+        msr     cntv_ctl_el0, x3
+
+        isb
+
+        mrs     x3, cntv_cval_el0
+        str     x3, [x0, #VCPU_TIMER_CNTV_CVAL]
+
+1:
+        // Allow physical timer/counter access for the host
+        mrs     x2, cnthctl_el2
+        orr     x2, x2, #3
+        msr     cnthctl_el2, x2
+
+        // Clear cntvoff for the host
+        msr     cntvoff_el2, xzr
+.endm
+
+.macro restore_timer_state
+        // x0: vcpu pointer
+        // Disallow physical timer access for the guest
+        // Physical counter access is allowed
+        mrs     x2, cnthctl_el2
+        orr     x2, x2, #1
+        bic     x2, x2, #2
+        msr     cnthctl_el2, x2
+
+        ldr     x2, [x0, #VCPU_KVM]
+        kern_hyp_va x2
+        ldr     w3, [x2, #KVM_TIMER_ENABLED]
+        cbz     w3, 1f
+
+        ldr     x3, [x2, #KVM_TIMER_CNTVOFF]
+        msr     cntvoff_el2, x3
+        ldr     x2, [x0, #VCPU_TIMER_CNTV_CVAL]
+        msr     cntv_cval_el0, x2
+        isb
+
+        ldr     w2, [x0, #VCPU_TIMER_CNTV_CTL]
+        and     x2, x2, #3
+        msr     cntv_ctl_el0, x2
+1:
+.endm
+
 __save_sysregs:
         save_sysregs
         ret
@@ -433,6 +487,7 @@ ENTRY(__kvm_vcpu_run)
         activate_vm
 
         restore_vgic_state
+        restore_timer_state
 
         // Guest context
         add     x2, x0, #VCPU_CONTEXT
@@ -455,6 +510,7 @@ __kvm_vcpu_return:
         bl __save_fpsimd
         bl __save_sysregs
 
+        save_timer_state
         save_vgic_state
 
         deactivate_traps
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index f6536a06231a..766150ac76ed 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -23,6 +23,8 @@
 #include <linux/kvm_host.h>
 #include <linux/kvm.h>
 
+#include <kvm/arm_arch_timer.h>
+
 #include <asm/cputype.h>
 #include <asm/ptrace.h>
 #include <asm/kvm_arm.h>
@@ -36,6 +38,11 @@ static const struct kvm_regs default_regs_reset = {
                         PSR_F_BIT | PSR_D_BIT),
 };
 
+static const struct kvm_irq_level default_vtimer_irq = {
+        .irq    = 27,
+        .level  = 1,
+};
+
 int kvm_arch_dev_ioctl_check_extension(long ext)
 {
         int r;
@@ -58,11 +65,13 @@ int kvm_arch_dev_ioctl_check_extension(long ext)
  */
 int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 {
+        const struct kvm_irq_level *cpu_vtimer_irq;
         const struct kvm_regs *cpu_reset;
 
         switch (vcpu->arch.target) {
         default:
                 cpu_reset = &default_regs_reset;
+                cpu_vtimer_irq = &default_vtimer_irq;
                 break;
         }
 
@@ -72,5 +81,8 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
         /* Reset system registers */
         kvm_reset_sys_regs(vcpu);
 
+        /* Reset timer */
+        kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);
+
         return 0;
 }