From 3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22 Mon Sep 17 00:00:00 2001
From: Atish Patra <atish.patra@wdc.com>
Date: Mon, 27 Sep 2021 17:10:11 +0530
Subject: RISC-V: KVM: Add timer functionality

The RISC-V hypervisor specification doesn't have any virtual timer
feature.

Due to this, the guest VCPU timer will be programmed via SBI calls.
The host will use a separate hrtimer event for each guest VCPU to
provide timer functionality. We inject a virtual timer interrupt to
the guest VCPU whenever the guest VCPU hrtimer event expires.

This patch adds guest VCPU timer implementation along with ONE_REG
interface to access VCPU timer state from user space.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 drivers/clocksource/timer-riscv.c | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'drivers/clocksource/timer-riscv.c')

diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index c51c5ed15aa7..1767f8bf2013 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -13,10 +13,12 @@
 #include <linux/delay.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
+#include <linux/module.h>
 #include <linux/sched_clock.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
+#include <clocksource/timer-riscv.h>
 #include <asm/smp.h>
 #include <asm/sbi.h>
 #include <asm/timex.h>
@@ -79,6 +81,13 @@ static int riscv_timer_dying_cpu(unsigned int cpu)
 	return 0;
 }
 
+void riscv_cs_get_mult_shift(u32 *mult, u32 *shift)
+{
+	*mult = riscv_clocksource.mult;
+	*shift = riscv_clocksource.shift;
+}
+EXPORT_SYMBOL_GPL(riscv_cs_get_mult_shift);
+
 /* called directly from the low-level interrupt handler */
 static irqreturn_t riscv_timer_interrupt(int irq, void *dev_id)
 {
-- 
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