KVM: arm/arm64: Emulate the EL1 phys timer registers

Emulate read and write operations to CNTP_TVAL, CNTP_CVAL and CNTP_CTL.
Now VMs are able to use the EL1 physical timer.

Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 1cd3464ff88d8add7ff9b6f9acaf2da9f38041bf..0e26f8c2b56f8270a6ff4bc5d3a3a1ba2e1c3210 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -824,7 +824,14 @@ static bool access_cntp_tval(struct kvm_vcpu *vcpu,
                struct sys_reg_params *p,
                const struct sys_reg_desc *r)
 {
-       kvm_inject_undefined(vcpu);
+       struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+       u64 now = kvm_phys_timer_read();
+
+       if (p->is_write)
+               ptimer->cnt_cval = p->regval + now;
+       else
+               p->regval = ptimer->cnt_cval - now;
+
        return true;
 }
 
@@ -832,7 +839,25 @@ static bool access_cntp_ctl(struct kvm_vcpu *vcpu,
                struct sys_reg_params *p,
                const struct sys_reg_desc *r)
 {
-       kvm_inject_undefined(vcpu);
+       struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+       if (p->is_write) {
+               /* ISTATUS bit is read-only */
+               ptimer->cnt_ctl = p->regval & ~ARCH_TIMER_CTRL_IT_STAT;
+       } else {
+               u64 now = kvm_phys_timer_read();
+
+               p->regval = ptimer->cnt_ctl;
+               /*
+                * Set ISTATUS bit if it's expired.
+                * Note that according to ARMv8 ARM Issue A.k, ISTATUS bit is
+                * UNKNOWN when ENABLE bit is 0, so we chose to set ISTATUS bit
+                * regardless of ENABLE bit for our implementation convenience.
+                */
+               if (ptimer->cnt_cval <= now)
+                       p->regval |= ARCH_TIMER_CTRL_IT_STAT;
+       }
+
        return true;
 }
 
@@ -840,7 +865,13 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
                struct sys_reg_params *p,
                const struct sys_reg_desc *r)
 {
-       kvm_inject_undefined(vcpu);
+       struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
+
+       if (p->is_write)
+               ptimer->cnt_cval = p->regval;
+       else
+               p->regval = ptimer->cnt_cval;
+
        return true;
 }
 

diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
index f1d2fba0b9c657d92ecb7a90a716cadd4cf592c6..fe797d6ef89d90e3163c0e4f927286b314c8d5c8 100644 (file)
--- a/include/kvm/arm_arch_timer.h
+++ b/include/kvm/arm_arch_timer.h
@@ -72,6 +72,8 @@ bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx);
 void kvm_timer_schedule(struct kvm_vcpu *vcpu);
 void kvm_timer_unschedule(struct kvm_vcpu *vcpu);
 
+u64 kvm_phys_timer_read(void);
+
 void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu);
 
 void kvm_timer_init_vhe(void);

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 33257b560f7428e92b09ba2d9995506591aeacb3..35d7100e0815c4fc34acdebc17e794dfd569dbcf 100644 (file)
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -40,7 +40,7 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
        vcpu_vtimer(vcpu)->active_cleared_last = false;
 }
 
-static u64 kvm_phys_timer_read(void)
+u64 kvm_phys_timer_read(void)
 {
        return timecounter->cc->read(timecounter->cc);
 }