1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
4 */
5
6 #include <linux/kvm_host.h>
7 #include <asm/kvm_csr.h>
8 #include <asm/kvm_vcpu.h>
9
10 /*
11 * ktime_to_tick() - Scale ktime_t to timer tick value.
12 */
13 static inline u64 ktime_to_tick(struct kvm_vcpu *vcpu, ktime_t now)
14 {
15 u64 delta;
16
17 delta = ktime_to_ns(now);
18 return div_u64(delta * vcpu->arch.timer_mhz, MNSEC_PER_SEC);
19 }
20
21 static inline u64 tick_to_ns(struct kvm_vcpu *vcpu, u64 tick)
22 {
23 return div_u64(tick * MNSEC_PER_SEC, vcpu->arch.timer_mhz);
24 }
25
26 /* Low level hrtimer wake routine */
27 enum hrtimer_restart kvm_swtimer_wakeup(struct hrtimer *timer)
28 {
29 struct kvm_vcpu *vcpu;
30
31 vcpu = container_of(timer, struct kvm_vcpu, arch.swtimer);
32 kvm_queue_irq(vcpu, INT_TI);
33 rcuwait_wake_up(&vcpu->wait);
34
35 return HRTIMER_NORESTART;
36 }
37
38 /*
39 * Initialise the timer to the specified frequency, zero it
40 */
41 void kvm_init_timer(struct kvm_vcpu *vcpu, unsigned long timer_hz)
42 {
43 vcpu->arch.timer_mhz = timer_hz >> 20;
44
45 /* Starting at 0 */
46 kvm_write_sw_gcsr(vcpu->arch.csr, LOONGARCH_CSR_TVAL, 0);
47 }
48
49 /*
50 * Restore soft timer state from saved context.
51 */
52 void kvm_restore_timer(struct kvm_vcpu *vcpu)
53 {
54 unsigned long cfg, estat;
55 unsigned long ticks, delta, period;
56 ktime_t expire, now;
57 struct loongarch_csrs *csr = vcpu->arch.csr;
58
59 /*
60 * Set guest stable timer cfg csr
61 * Disable timer before restore estat CSR register, avoid to
62 * get invalid timer interrupt for old timer cfg
63 */
64 cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG);
65
66 write_gcsr_timercfg(0);
67 kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_ESTAT);
68 kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_TCFG);
69 if (!(cfg & CSR_TCFG_EN)) {
70 /* Guest timer is disabled, just restore timer registers */
71 kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_TVAL);
72 return;
73 }
74
75 /*
76 * Freeze the soft-timer and sync the guest stable timer with it.
77 */
78 if (kvm_vcpu_is_blocking(vcpu))
79 hrtimer_cancel(&vcpu->arch.swtimer);
80
81 /*
82 * From LoongArch Reference Manual Volume 1 Chapter 7.6.2
83 * If oneshot timer is fired, CSR TVAL will be -1, there are two
84 * conditions:
85 * 1) timer is fired during exiting to host
86 * 2) timer is fired and vm is doing timer irq, and then exiting to
87 * host. Host should not inject timer irq to avoid spurious
88 * timer interrupt again
89 */
90 ticks = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL);
91 estat = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
92 if (!(cfg & CSR_TCFG_PERIOD) && (ticks > cfg)) {
93 /*
94 * Writing 0 to LOONGARCH_CSR_TVAL will inject timer irq
95 * and set CSR TVAL with -1
96 */
97 write_gcsr_timertick(0);
98
99 /*
100 * Writing CSR_TINTCLR_TI to LOONGARCH_CSR_TINTCLR will clear
101 * timer interrupt, and CSR TVAL keeps unchanged with -1, it
102 * avoids spurious timer interrupt
103 */
104 if (!(estat & CPU_TIMER))
105 gcsr_write(CSR_TINTCLR_TI, LOONGARCH_CSR_TINTCLR);
106 return;
107 }
108
109 /*
110 * Set remainder tick value if not expired
111 */
112 delta = 0;
113 now = ktime_get();
114 expire = vcpu->arch.expire;
115 if (ktime_before(now, expire))
116 delta = ktime_to_tick(vcpu, ktime_sub(expire, now));
117 else if (cfg & CSR_TCFG_PERIOD) {
118 period = cfg & CSR_TCFG_VAL;
119 delta = ktime_to_tick(vcpu, ktime_sub(now, expire));
120 delta = period - (delta % period);
121
122 /*
123 * Inject timer here though sw timer should inject timer
124 * interrupt async already, since sw timer may be cancelled
125 * during injecting intr async
126 */
127 kvm_queue_irq(vcpu, INT_TI);
128 }
129
130 write_gcsr_timertick(delta);
131 }
132
133 /*
134 * Save guest timer state and switch to software emulation of guest
135 * timer. The hard timer must already be in use, so preemption should be
136 * disabled.
137 */
138 static void _kvm_save_timer(struct kvm_vcpu *vcpu)
139 {
140 unsigned long ticks, delta, cfg;
141 ktime_t expire;
142 struct loongarch_csrs *csr = vcpu->arch.csr;
143
144 cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG);
145 ticks = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL);
146
147 /*
148 * From LoongArch Reference Manual Volume 1 Chapter 7.6.2
149 * If period timer is fired, CSR TVAL will be reloaded from CSR TCFG
150 * If oneshot timer is fired, CSR TVAL will be -1
151 * Here judge one-shot timer fired by checking whether TVAL is larger
152 * than TCFG
153 */
154 if (ticks < cfg)
155 delta = tick_to_ns(vcpu, ticks);
156 else
157 delta = 0;
158
159 expire = ktime_add_ns(ktime_get(), delta);
160 vcpu->arch.expire = expire;
161 if (kvm_vcpu_is_blocking(vcpu)) {
162
163 /*
164 * HRTIMER_MODE_PINNED is suggested since vcpu may run in
165 * the same physical cpu in next time
166 */
167 hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED);
168 }
169 }
170
171 /*
172 * Save guest timer state and switch to soft guest timer if hard timer was in
173 * use.
174 */
175 void kvm_save_timer(struct kvm_vcpu *vcpu)
176 {
177 struct loongarch_csrs *csr = vcpu->arch.csr;
178
179 preempt_disable();
180
181 /* Save hard timer state */
182 kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TCFG);
183 kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TVAL);
184 if (kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG) & CSR_TCFG_EN)
185 _kvm_save_timer(vcpu);
186
187 /* Save timer-related state to vCPU context */
188 kvm_save_hw_gcsr(csr, LOONGARCH_CSR_ESTAT);
189 preempt_enable();
190 }
191
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.