linux/arch/loongarch/kernel/paravirt.c
Bibo Mao 03779999ac LoongArch: KVM: Add PV steal time support in guest side
Per-cpu struct kvm_steal_time is added here, its size is 64 bytes and
also defined as 64 bytes, so that the whole structure is in one physical
page.

When a VCPU is online, function pv_enable_steal_time() is called. This
function will pass guest physical address of struct kvm_steal_time and
tells hypervisor to enable steal time. When a vcpu is offline, physical
address is set as 0 and tells hypervisor to disable steal time.

Here is an output of vmstat on guest when there is workload on both host
and guest. It shows steal time stat information.

procs -----------memory---------- -----io---- -system-- ------cpu-----
 r  b   swpd   free  inact active   bi    bo   in   cs us sy id wa st
15  1      0 7583616 184112  72208    20    0  162   52 31  6 43  0 20
17  0      0 7583616 184704  72192    0     0 6318 6885  5 60  8  5 22
16  0      0 7583616 185392  72144    0     0 1766 1081  0 49  0  1 50
16  0      0 7583616 184816  72304    0     0 6300 6166  4 62 12  2 20
18  0      0 7583632 184480  72240    0     0 2814 1754  2 58  4  1 35

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-07-09 16:25:51 +08:00

297 lines
6.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/jump_label.h>
#include <linux/kvm_para.h>
#include <linux/reboot.h>
#include <linux/static_call.h>
#include <asm/paravirt.h>
static int has_steal_clock;
struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;
static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
static u64 native_steal_clock(int cpu)
{
return 0;
}
DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
static bool steal_acc = true;
static int __init parse_no_stealacc(char *arg)
{
steal_acc = false;
return 0;
}
early_param("no-steal-acc", parse_no_stealacc);
static u64 paravt_steal_clock(int cpu)
{
int version;
u64 steal;
struct kvm_steal_time *src;
src = &per_cpu(steal_time, cpu);
do {
version = src->version;
virt_rmb(); /* Make sure that the version is read before the steal */
steal = src->steal;
virt_rmb(); /* Make sure that the steal is read before the next version */
} while ((version & 1) || (version != src->version));
return steal;
}
#ifdef CONFIG_SMP
static void pv_send_ipi_single(int cpu, unsigned int action)
{
int min, old;
irq_cpustat_t *info = &per_cpu(irq_stat, cpu);
old = atomic_fetch_or(BIT(action), &info->message);
if (old)
return;
min = cpu_logical_map(cpu);
kvm_hypercall3(KVM_HCALL_FUNC_IPI, 1, 0, min);
}
#define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)
static void pv_send_ipi_mask(const struct cpumask *mask, unsigned int action)
{
int i, cpu, min = 0, max = 0, old;
__uint128_t bitmap = 0;
irq_cpustat_t *info;
if (cpumask_empty(mask))
return;
action = BIT(action);
for_each_cpu(i, mask) {
info = &per_cpu(irq_stat, i);
old = atomic_fetch_or(action, &info->message);
if (old)
continue;
cpu = cpu_logical_map(i);
if (!bitmap) {
min = max = cpu;
} else if (cpu < min && cpu > (max - KVM_IPI_CLUSTER_SIZE)) {
/* cpu < min, and bitmap still enough */
bitmap <<= min - cpu;
min = cpu;
} else if (cpu > min && cpu < (min + KVM_IPI_CLUSTER_SIZE)) {
/* cpu > min, and bitmap still enough */
max = cpu > max ? cpu : max;
} else {
/*
* With cpu, bitmap will exceed KVM_IPI_CLUSTER_SIZE,
* send IPI here directly and skip the remaining CPUs.
*/
kvm_hypercall3(KVM_HCALL_FUNC_IPI, (unsigned long)bitmap,
(unsigned long)(bitmap >> BITS_PER_LONG), min);
min = max = cpu;
bitmap = 0;
}
__set_bit(cpu - min, (unsigned long *)&bitmap);
}
if (bitmap)
kvm_hypercall3(KVM_HCALL_FUNC_IPI, (unsigned long)bitmap,
(unsigned long)(bitmap >> BITS_PER_LONG), min);
}
static irqreturn_t pv_ipi_interrupt(int irq, void *dev)
{
u32 action;
irq_cpustat_t *info;
/* Clear SWI interrupt */
clear_csr_estat(1 << INT_SWI0);
info = this_cpu_ptr(&irq_stat);
action = atomic_xchg(&info->message, 0);
if (action & SMP_RESCHEDULE) {
scheduler_ipi();
info->ipi_irqs[IPI_RESCHEDULE]++;
}
if (action & SMP_CALL_FUNCTION) {
generic_smp_call_function_interrupt();
info->ipi_irqs[IPI_CALL_FUNCTION]++;
}
return IRQ_HANDLED;
}
static void pv_init_ipi(void)
{
int r, swi;
swi = get_percpu_irq(INT_SWI0);
if (swi < 0)
panic("SWI0 IRQ mapping failed\n");
irq_set_percpu_devid(swi);
r = request_percpu_irq(swi, pv_ipi_interrupt, "SWI0-IPI", &irq_stat);
if (r < 0)
panic("SWI0 IRQ request failed\n");
}
#endif
static bool kvm_para_available(void)
{
int config;
static int hypervisor_type;
if (!hypervisor_type) {
config = read_cpucfg(CPUCFG_KVM_SIG);
if (!memcmp(&config, KVM_SIGNATURE, 4))
hypervisor_type = HYPERVISOR_KVM;
}
return hypervisor_type == HYPERVISOR_KVM;
}
int __init pv_ipi_init(void)
{
int feature;
if (!cpu_has_hypervisor)
return 0;
if (!kvm_para_available())
return 0;
feature = read_cpucfg(CPUCFG_KVM_FEATURE);
if (!(feature & KVM_FEATURE_IPI))
return 0;
#ifdef CONFIG_SMP
mp_ops.init_ipi = pv_init_ipi;
mp_ops.send_ipi_single = pv_send_ipi_single;
mp_ops.send_ipi_mask = pv_send_ipi_mask;
#endif
return 0;
}
static int pv_enable_steal_time(void)
{
int cpu = smp_processor_id();
unsigned long addr;
struct kvm_steal_time *st;
if (!has_steal_clock)
return -EPERM;
st = &per_cpu(steal_time, cpu);
addr = per_cpu_ptr_to_phys(st);
/* The whole structure kvm_steal_time should be in one page */
if (PFN_DOWN(addr) != PFN_DOWN(addr + sizeof(*st))) {
pr_warn("Illegal PV steal time addr %lx\n", addr);
return -EFAULT;
}
addr |= KVM_STEAL_PHYS_VALID;
kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, addr);
return 0;
}
static void pv_disable_steal_time(void)
{
if (has_steal_clock)
kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, 0);
}
#ifdef CONFIG_SMP
static int pv_time_cpu_online(unsigned int cpu)
{
unsigned long flags;
local_irq_save(flags);
pv_enable_steal_time();
local_irq_restore(flags);
return 0;
}
static int pv_time_cpu_down_prepare(unsigned int cpu)
{
unsigned long flags;
local_irq_save(flags);
pv_disable_steal_time();
local_irq_restore(flags);
return 0;
}
#endif
static void pv_cpu_reboot(void *unused)
{
pv_disable_steal_time();
}
static int pv_reboot_notify(struct notifier_block *nb, unsigned long code, void *unused)
{
on_each_cpu(pv_cpu_reboot, NULL, 1);
return NOTIFY_DONE;
}
static struct notifier_block pv_reboot_nb = {
.notifier_call = pv_reboot_notify,
};
int __init pv_time_init(void)
{
int r, feature;
if (!cpu_has_hypervisor)
return 0;
if (!kvm_para_available())
return 0;
feature = read_cpucfg(CPUCFG_KVM_FEATURE);
if (!(feature & KVM_FEATURE_STEAL_TIME))
return 0;
has_steal_clock = 1;
r = pv_enable_steal_time();
if (r < 0) {
has_steal_clock = 0;
return 0;
}
register_reboot_notifier(&pv_reboot_nb);
#ifdef CONFIG_SMP
r = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
"loongarch/pv_time:online",
pv_time_cpu_online, pv_time_cpu_down_prepare);
if (r < 0) {
has_steal_clock = 0;
pr_err("Failed to install cpu hotplug callbacks\n");
return r;
}
#endif
static_call_update(pv_steal_clock, paravt_steal_clock);
static_key_slow_inc(&paravirt_steal_enabled);
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
if (steal_acc)
static_key_slow_inc(&paravirt_steal_rq_enabled);
#endif
pr_info("Using paravirt steal-time\n");
return 0;
}