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RISC-V: KVM: Add timer functionality

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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>
This commit is contained in:
Atish Patra 2021-09-27 17:10:11 +05:30 • committed by Anup Patel
parent 9955371cc0
commit 3a9f66cb25
9 changed files with 334 additions and 1 deletions
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44
arch/riscv/include/asm/kvm_vcpu_timer.h Normal file
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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2019 Western Digital Corporation or its affiliates.
*
* Authors:
* Atish Patra <atish.patra@wdc.com>
*/
#ifndef __KVM_VCPU_RISCV_TIMER_H
#define __KVM_VCPU_RISCV_TIMER_H
#include <linux/hrtimer.h>
struct kvm_guest_timer {
/* Mult & Shift values to get nanoseconds from cycles */
u32 nsec_mult;
u32 nsec_shift;
/* Time delta value */
u64 time_delta;
};
struct kvm_vcpu_timer {
/* Flag for whether init is done */
bool init_done;
/* Flag for whether timer event is configured */
bool next_set;
/* Next timer event cycles */
u64 next_cycles;
/* Underlying hrtimer instance */
struct hrtimer hrt;
};
int kvm_riscv_vcpu_timer_next_event(struct kvm_vcpu *vcpu, u64 ncycles);
int kvm_riscv_vcpu_get_reg_timer(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg);
int kvm_riscv_vcpu_set_reg_timer(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg);
int kvm_riscv_vcpu_timer_init(struct kvm_vcpu *vcpu);
int kvm_riscv_vcpu_timer_deinit(struct kvm_vcpu *vcpu);
int kvm_riscv_vcpu_timer_reset(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu);
int kvm_riscv_guest_timer_init(struct kvm *kvm);
#endif