ARM: KVM: Add timer save/restore

This patch shouldn't exist, as we should be able to reuse the
arm64 version for free. I'll get there eventually, but in the
meantime I need a timer ticking.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/kvm/hyp/Makefile

@@ -4,3 +4,4 @@
 
 obj-$(CONFIG_KVM_ARM_HOST) += tlb.o
 obj-$(CONFIG_KVM_ARM_HOST) += cp15-sr.o
+obj-$(CONFIG_KVM_ARM_HOST) += timer-sr.o

arch/arm/kvm/hyp/hyp.h

@@ -46,6 +46,9 @@
 #define TTBR1		__ACCESS_CP15_64(1, c2)
 #define VTTBR		__ACCESS_CP15_64(6, c2)
 #define PAR		__ACCESS_CP15_64(0, c7)
+#define CNTV_CVAL	__ACCESS_CP15_64(3, c14)
+#define CNTVOFF		__ACCESS_CP15_64(4, c14)
+
 #define CSSELR		__ACCESS_CP15(c0, 2, c0, 0)
 #define VMPIDR		__ACCESS_CP15(c0, 4, c0, 5)
 #define SCTLR		__ACCESS_CP15(c1, 0, c0, 0)
@@ -71,6 +74,11 @@
 #define TID_URO		__ACCESS_CP15(c13, 0, c0, 3)
 #define TID_PRIV	__ACCESS_CP15(c13, 0, c0, 4)
 #define CNTKCTL		__ACCESS_CP15(c14, 0, c1, 0)
+#define CNTV_CTL	__ACCESS_CP15(c14, 0, c3, 1)
+#define CNTHCTL		__ACCESS_CP15(c14, 4, c1, 0)
+
+void __timer_save_state(struct kvm_vcpu *vcpu);
+void __timer_restore_state(struct kvm_vcpu *vcpu);
 
 void __sysreg_save_state(struct kvm_cpu_context *ctxt);
 void __sysreg_restore_state(struct kvm_cpu_context *ctxt);

arch/arm/kvm/hyp/timer-sr.c

+/*
+ * Copyright (C) 2012-2015 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <clocksource/arm_arch_timer.h>
+#include <linux/compiler.h>
+#include <linux/kvm_host.h>
+
+#include <asm/kvm_mmu.h>
+
+#include "hyp.h"
+
+/* vcpu is already in the HYP VA space */
+void __hyp_text __timer_save_state(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	u64 val;
+
+	if (kvm->arch.timer.enabled) {
+		timer->cntv_ctl = read_sysreg(CNTV_CTL);
+		timer->cntv_cval = read_sysreg(CNTV_CVAL);
+	}
+
+	/* Disable the virtual timer */
+	write_sysreg(0, CNTV_CTL);
+
+	/* Allow physical timer/counter access for the host */
+	val = read_sysreg(CNTHCTL);
+	val |= CNTHCTL_EL1PCTEN | CNTHCTL_EL1PCEN;
+	write_sysreg(val, CNTHCTL);
+
+	/* Clear cntvoff for the host */
+	write_sysreg(0, CNTVOFF);
+}
+
+void __hyp_text __timer_restore_state(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	u64 val;
+
+	/*
+	 * Disallow physical timer access for the guest
+	 * Physical counter access is allowed
+	 */
+	val = read_sysreg(CNTHCTL);
+	val &= ~CNTHCTL_EL1PCEN;
+	val |= CNTHCTL_EL1PCTEN;
+	write_sysreg(val, CNTHCTL);
+
+	if (kvm->arch.timer.enabled) {
+		write_sysreg(kvm->arch.timer.cntvoff, CNTVOFF);
+		write_sysreg(timer->cntv_cval, CNTV_CVAL);
+		isb();
+		write_sysreg(timer->cntv_ctl, CNTV_CTL);
+	}
+}