From: Christoffer Dall <cdall@linaro.org>
Date: Fri, 16 Jun 2017 23:12:06 -0700
Subject: KVM: arm/arm64: Use kvm_arm_timer_set/get_reg for guest register
 traps
Patch-mainline: v4.15-rc1
Git-commit: c1b135af8387bc6c6d43ed61a65647c68f231ea1
References: bsc#1077761

When trapping on a guest access to one of the timer registers, we were
messing with the internals of the timer state from the sysregs handling
code, and that logic was about to receive more added complexity when
optimizing the timer handling code.

Therefore, since we already have timer register access functions (to
access registers from userspace), reuse those for the timer register
traps from a VM and let the timer code maintain its own consistency.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Alexander Graf <agraf@suse.de>
---
 arch/arm64/kvm/sys_regs.c |   41 ++++++++++++++---------------------------
 1 file changed, 14 insertions(+), 27 deletions(-)

--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -842,13 +842,16 @@
 		struct sys_reg_params *p,
 		const struct sys_reg_desc *r)
 {
-	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
 	u64 now = kvm_phys_timer_read();
+	u64 cval;
 
-	if (p->is_write)
-		ptimer->cnt_cval = p->regval + now;
-	else
-		p->regval = ptimer->cnt_cval - now;
+	if (p->is_write) {
+		kvm_arm_timer_set_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL,
+				      p->regval + now);
+	} else {
+		cval = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL);
+		p->regval = cval - now;
+	}
 
 	return true;
 }
@@ -857,24 +860,10 @@
 		struct sys_reg_params *p,
 		const struct sys_reg_desc *r)
 {
-	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;
-	}
+	if (p->is_write)
+		kvm_arm_timer_set_reg(vcpu, KVM_REG_ARM_PTIMER_CTL, p->regval);
+	else
+		p->regval = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_PTIMER_CTL);
 
 	return true;
 }
@@ -883,12 +872,10 @@
 		struct sys_reg_params *p,
 		const struct sys_reg_desc *r)
 {
-	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
-
 	if (p->is_write)
-		ptimer->cnt_cval = p->regval;
+		kvm_arm_timer_set_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL, p->regval);
 	else
-		p->regval = ptimer->cnt_cval;
+		p->regval = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL);
 
 	return true;
 }