linux/arch/mips/kvm/loongson_ipi.c
Huacai Chen f21db3090d KVM: MIPS: Add Loongson-3 Virtual IPI interrupt support
This patch add Loongson-3 Virtual IPI interrupt support in the kernel.
The current implementation of IPI emulation in QEMU is based on GIC for
MIPS, but Loongson-3 doesn't use GIC. Furthermore, IPI emulation in QEMU
is too expensive for performance (because of too many context switches
between Host and Guest). With current solution, the IPI delay may even
cause RCU stall warnings in a multi-core Guest. So, we design a faster
solution that emulate IPI interrupt in kernel (only used by Loongson-3
now).

Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <1590220602-3547-11-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-06-04 13:50:39 -04:00

215 lines
5.0 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Loongson-3 Virtual IPI interrupt support.
*
* Copyright (C) 2019 Loongson Technologies, Inc. All rights reserved.
*
* Authors: Chen Zhu <zhuchen@loongson.cn>
* Authors: Huacai Chen <chenhc@lemote.com>
*/
#include <linux/kvm_host.h>
#define IPI_BASE 0x3ff01000ULL
#define CORE0_STATUS_OFF 0x000
#define CORE0_EN_OFF 0x004
#define CORE0_SET_OFF 0x008
#define CORE0_CLEAR_OFF 0x00c
#define CORE0_BUF_20 0x020
#define CORE0_BUF_28 0x028
#define CORE0_BUF_30 0x030
#define CORE0_BUF_38 0x038
#define CORE1_STATUS_OFF 0x100
#define CORE1_EN_OFF 0x104
#define CORE1_SET_OFF 0x108
#define CORE1_CLEAR_OFF 0x10c
#define CORE1_BUF_20 0x120
#define CORE1_BUF_28 0x128
#define CORE1_BUF_30 0x130
#define CORE1_BUF_38 0x138
#define CORE2_STATUS_OFF 0x200
#define CORE2_EN_OFF 0x204
#define CORE2_SET_OFF 0x208
#define CORE2_CLEAR_OFF 0x20c
#define CORE2_BUF_20 0x220
#define CORE2_BUF_28 0x228
#define CORE2_BUF_30 0x230
#define CORE2_BUF_38 0x238
#define CORE3_STATUS_OFF 0x300
#define CORE3_EN_OFF 0x304
#define CORE3_SET_OFF 0x308
#define CORE3_CLEAR_OFF 0x30c
#define CORE3_BUF_20 0x320
#define CORE3_BUF_28 0x328
#define CORE3_BUF_30 0x330
#define CORE3_BUF_38 0x338
static int loongson_vipi_read(struct loongson_kvm_ipi *ipi,
gpa_t addr, int len, void *val)
{
uint32_t core = (addr >> 8) & 3;
uint32_t node = (addr >> 44) & 3;
uint32_t id = core + node * 4;
uint64_t offset = addr & 0xff;
void *pbuf;
struct ipi_state *s = &(ipi->ipistate[id]);
BUG_ON(offset & (len - 1));
switch (offset) {
case CORE0_STATUS_OFF:
*(uint64_t *)val = s->status;
break;
case CORE0_EN_OFF:
*(uint64_t *)val = s->en;
break;
case CORE0_SET_OFF:
*(uint64_t *)val = 0;
break;
case CORE0_CLEAR_OFF:
*(uint64_t *)val = 0;
break;
case CORE0_BUF_20 ... CORE0_BUF_38:
pbuf = (void *)s->buf + (offset - 0x20);
if (len == 8)
*(uint64_t *)val = *(uint64_t *)pbuf;
else /* Assume len == 4 */
*(uint32_t *)val = *(uint32_t *)pbuf;
break;
default:
pr_notice("%s with unknown addr %llx\n", __func__, addr);
break;
}
return 0;
}
static int loongson_vipi_write(struct loongson_kvm_ipi *ipi,
gpa_t addr, int len, const void *val)
{
uint32_t core = (addr >> 8) & 3;
uint32_t node = (addr >> 44) & 3;
uint32_t id = core + node * 4;
uint64_t data, offset = addr & 0xff;
void *pbuf;
struct kvm *kvm = ipi->kvm;
struct kvm_mips_interrupt irq;
struct ipi_state *s = &(ipi->ipistate[id]);
data = *(uint64_t *)val;
BUG_ON(offset & (len - 1));
switch (offset) {
case CORE0_STATUS_OFF:
break;
case CORE0_EN_OFF:
s->en = data;
break;
case CORE0_SET_OFF:
s->status |= data;
irq.cpu = id;
irq.irq = 6;
kvm_vcpu_ioctl_interrupt(kvm->vcpus[id], &irq);
break;
case CORE0_CLEAR_OFF:
s->status &= ~data;
if (!s->status) {
irq.cpu = id;
irq.irq = -6;
kvm_vcpu_ioctl_interrupt(kvm->vcpus[id], &irq);
}
break;
case CORE0_BUF_20 ... CORE0_BUF_38:
pbuf = (void *)s->buf + (offset - 0x20);
if (len == 8)
*(uint64_t *)pbuf = (uint64_t)data;
else /* Assume len == 4 */
*(uint32_t *)pbuf = (uint32_t)data;
break;
default:
pr_notice("%s with unknown addr %llx\n", __func__, addr);
break;
}
return 0;
}
static int kvm_ipi_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, void *val)
{
unsigned long flags;
struct loongson_kvm_ipi *ipi;
struct ipi_io_device *ipi_device;
ipi_device = container_of(dev, struct ipi_io_device, device);
ipi = ipi_device->ipi;
spin_lock_irqsave(&ipi->lock, flags);
loongson_vipi_read(ipi, addr, len, val);
spin_unlock_irqrestore(&ipi->lock, flags);
return 0;
}
static int kvm_ipi_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, const void *val)
{
unsigned long flags;
struct loongson_kvm_ipi *ipi;
struct ipi_io_device *ipi_device;
ipi_device = container_of(dev, struct ipi_io_device, device);
ipi = ipi_device->ipi;
spin_lock_irqsave(&ipi->lock, flags);
loongson_vipi_write(ipi, addr, len, val);
spin_unlock_irqrestore(&ipi->lock, flags);
return 0;
}
static const struct kvm_io_device_ops kvm_ipi_ops = {
.read = kvm_ipi_read,
.write = kvm_ipi_write,
};
void kvm_init_loongson_ipi(struct kvm *kvm)
{
int i;
unsigned long addr;
struct loongson_kvm_ipi *s;
struct kvm_io_device *device;
s = &kvm->arch.ipi;
s->kvm = kvm;
spin_lock_init(&s->lock);
/*
* Initialize IPI device
*/
for (i = 0; i < 4; i++) {
device = &s->dev_ipi[i].device;
kvm_iodevice_init(device, &kvm_ipi_ops);
addr = (((unsigned long)i) << 44) + IPI_BASE;
mutex_lock(&kvm->slots_lock);
kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, addr, 0x400, device);
mutex_unlock(&kvm->slots_lock);
s->dev_ipi[i].ipi = s;
s->dev_ipi[i].node_id = i;
}
}