Re: [PATCH v8 3/3] irqchip/loongson-eiointc: Add extioi virt extension support

[Huacai Chen]

Hi, Thomas,

On Fri, Aug 30, 2024 at 5:32 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
>
> Interrupts can be routed to maximal four virtual CPUs with one HW
> EIOINTC interrupt controller model, since interrupt routing is encoded with
> CPU bitmap and EIOINTC node combined method. Here add the EIOINTC virt
> extension support so that interrupts can be routed to 256 vCPUs on
> hypervisor mode. CPU bitmap is replaced with normal encoding and EIOINTC
> node type is removed, so there are 8 bits for cpu selection, at most 256
> vCPUs are supported for interrupt routing.
This patch is OK for me now, but seems it depends on the first two,
and the first two will get upstream via loongarch-kvm tree. So is that
possible to also apply this one to loongarch-kvm with your Acked-by?

Huacai

>
> Co-developed-by: Song Gao <gaosong@xxxxxxxxxxx>
> Signed-off-by: Song Gao <gaosong@xxxxxxxxxxx>
> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> ---
>  .../arch/loongarch/irq-chip-model.rst         |  64 ++++++++++
>  .../zh_CN/arch/loongarch/irq-chip-model.rst   |  55 +++++++++
>  arch/loongarch/include/asm/irq.h              |   1 +
>  drivers/irqchip/irq-loongson-eiointc.c        | 112 ++++++++++++++----
>  4 files changed, 211 insertions(+), 21 deletions(-)
>
> diff --git a/Documentation/arch/loongarch/irq-chip-model.rst b/Documentation/arch/loongarch/irq-chip-model.rst
> index 7988f4192363..d2350780ad1d 100644
> --- a/Documentation/arch/loongarch/irq-chip-model.rst
> +++ b/Documentation/arch/loongarch/irq-chip-model.rst
> @@ -85,6 +85,70 @@ to CPUINTC directly::
>      | Devices |
>      +---------+
>
> +Virtual extended IRQ model
> +==========================
> +
> +In this model, IPI (Inter-Processor Interrupt) and CPU Local Timer interrupt
> +go to CPUINTC directly, CPU UARTS interrupts go to PCH-PIC, while all other
> +devices interrupts go to PCH-PIC/PCH-MSI and gathered by V-EIOINTC (Virtual
> +Extended I/O Interrupt Controller), and then go to CPUINTC directly::
> +
> +       +-----+    +-------------------+     +-------+
> +       | IPI |--> | CPUINTC(0-255vcpu)| <-- | Timer |
> +       +-----+    +-------------------+     +-------+
> +                            ^
> +                            |
> +                      +-----------+
> +                      | V-EIOINTC |
> +                      +-----------+
> +                       ^         ^
> +                       |         |
> +                +---------+ +---------+
> +                | PCH-PIC | | PCH-MSI |
> +                +---------+ +---------+
> +                  ^      ^          ^
> +                  |      |          |
> +           +--------+ +---------+ +---------+
> +           | UARTs  | | Devices | | Devices |
> +           +--------+ +---------+ +---------+
> +
> +
> +Description
> +-----------
> +V-EIOINTC (Virtual Extended I/O Interrupt Controller) is an extension of
> +EIOINTC, it only works in VM mode which runs in KVM hypervisor. Interrupts can
> +be routed to up to four vCPUs via standard EIOINTC, however with V-EIOINTC
> +interrupts can be routed to up to 256 virtual cpus.
> +
> +With standard EIOINTC, interrupt routing setting includes two parts: eight
> +bits for CPU selection and four bits for CPU IP (Interrupt Pin) selection.
> +For CPU selection there is four bits for EIOINTC node selection, four bits
> +for EIOINTC CPU selection. Bitmap method is used for CPU selection and
> +CPU IP selection, so interrupt can only route to CPU0 - CPU3 and IP0-IP3 in
> +one EIOINTC node.
> +
> +With V-EIOINTC it supports to route more CPUs and CPU IP (Interrupt Pin),
> +there are two newly added registers with V-EIOINTC.
> +
> +EXTIOI_VIRT_FEATURES
> +--------------------
> +This register is read-only register, which indicates supported features with
> +V-EIOINTC. Feature EXTIOI_HAS_INT_ENCODE and EXTIOI_HAS_CPU_ENCODE is added.
> +
> +Feature EXTIOI_HAS_INT_ENCODE is part of standard EIOINTC. If it is 1, it
> +indicates that CPU Interrupt Pin selection can be normal method rather than
> +bitmap method, so interrupt can be routed to IP0 - IP15.
> +
> +Feature EXTIOI_HAS_CPU_ENCODE is entension of V-EIOINTC. If it is 1, it
> +indicates that CPU selection can be normal method rather than bitmap method,
> +so interrupt can be routed to CPU0 - CPU255.
> +
> +EXTIOI_VIRT_CONFIG
> +------------------
> +This register is read-write register, for compatibility intterupt routed uses
> +the default method which is the same with standard EIOINTC. If the bit is set
> +with 1, it indicated HW to use normal method rather than bitmap method.
> +
>  ACPI-related definitions
>  ========================
>
> diff --git a/Documentation/translations/zh_CN/arch/loongarch/irq-chip-model.rst b/Documentation/translations/zh_CN/arch/loongarch/irq-chip-model.rst
> index f1e9ab18206c..d696bd394c02 100644
> --- a/Documentation/translations/zh_CN/arch/loongarch/irq-chip-model.rst
> +++ b/Documentation/translations/zh_CN/arch/loongarch/irq-chip-model.rst
> @@ -87,6 +87,61 @@ PCH-LPC/PCH-MSI，然后被EIOINTC统一收集，再直接到达CPUINTC::
>      | Devices |
>      +---------+
>
> +虚拟扩展IRQ模型
> +===============
> +
> +在这种模型里面, IPI(Inter-Processor Interrupt) 和CPU本地时钟中断直接发送到CPUINTC,
> +CPU串口 (UARTs) 中断发送到PCH-PIC, 而其他所有设备的中断则分别发送到所连接的PCH_PIC/
> +PCH-MSI, 然后V-EIOINTC统一收集，再直接到达CPUINTC::
> +
> +        +-----+    +-------------------+     +-------+
> +        | IPI |--> | CPUINTC(0-255vcpu)| <-- | Timer |
> +        +-----+    +-------------------+     +-------+
> +                             ^
> +                             |
> +                       +-----------+
> +                       | V-EIOINTC |
> +                       +-----------+
> +                        ^         ^
> +                        |         |
> +                 +---------+ +---------+
> +                 | PCH-PIC | | PCH-MSI |
> +                 +---------+ +---------+
> +                   ^      ^          ^
> +                   |      |          |
> +            +--------+ +---------+ +---------+
> +            | UARTs  | | Devices | | Devices |
> +            +--------+ +---------+ +---------+
> +
> +V-EIOINTC 是EIOINTC的扩展, 仅工作在hyperisor模式下, 中断经EIOINTC最多可个路由到４个
> +虚拟cpu. 但中断经V-EIOINTC最多可个路由到256个虚拟cpu.
> +
> +传统的EIOINTC中断控制器，中断路由分为两个部分：8比特用于控制路由到哪个CPU，
> +4比特用于控制路由到特定CPU的哪个中断管脚.控制CPU路由的8比特前4比特用于控制
> +路由到哪个EIOINTC节点，后4比特用于控制此节点哪个CPU。中断路由在选择CPU路由
> +和CPU中断管脚路由时，使用bitmap编码方式而不是正常编码方式，所以对于一个
> +EIOINTC中断控制器节点，中断只能路由到CPU0 - CPU3，中断管教IP0-IP3。
> +
> +V-EIOINTC新增了两个寄存器，支持中断路由到更多CPU个和中断管脚。
> +
> +V-EIOINTC功能寄存器
> +-------------------
> +功能寄存器是只读寄存器，用于显示V-EIOINTC支持的特性，目前两个支持两个特性
> +EXTIOI_HAS_INT_ENCODE 和 EXTIOI_HAS_CPU_ENCODE。
> +
> +特性EXTIOI_HAS_INT_ENCODE是传统EIOINTC中断控制器的一个特性，如果此比特为1，
> +显示CPU中断管脚路由方式支持正常编码，而不是bitmap编码，所以中断可以路由到
> +管脚IP0 - IP15。
> +
> +特性EXTIOI_HAS_CPU_ENCODE是V-EIOINTC新增特性，如果此比特为1，表示CPU路由
> +方式支持正常编码，而不是bitmap编码，所以中断可以路由到CPU0 - CPU255。
> +
> +V-EIOINTC配置寄存器
> +-------------------
> +配置寄存器是可读写寄存器，为了兼容性考虑，如果不写此寄存器，中断路由采用
> +和传统EIOINTC相同的路由设置。如果对应比特设置为1，表示采用正常路由方式而
> +不是bitmap编码的路由方式。
> +
>  ACPI相关的定义
>  ==============
>
> diff --git a/arch/loongarch/include/asm/irq.h b/arch/loongarch/include/asm/irq.h
> index 480418bc5071..ce85d4c7d225 100644
> --- a/arch/loongarch/include/asm/irq.h
> +++ b/arch/loongarch/include/asm/irq.h
> @@ -54,6 +54,7 @@ extern struct acpi_vector_group pch_group[MAX_IO_PICS];
>  extern struct acpi_vector_group msi_group[MAX_IO_PICS];
>
>  #define CORES_PER_EIO_NODE     4
> +#define CORES_PER_VEIO_NODE    256
>
>  #define LOONGSON_CPU_UART0_VEC         10 /* CPU UART0 */
>  #define LOONGSON_CPU_THSENS_VEC                14 /* CPU Thsens */
> diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> index b1f2080be2be..763306cdbdfe 100644
> --- a/drivers/irqchip/irq-loongson-eiointc.c
> +++ b/drivers/irqchip/irq-loongson-eiointc.c
> @@ -14,6 +14,7 @@
>  #include <linux/irqdomain.h>
>  #include <linux/irqchip/chained_irq.h>
>  #include <linux/kernel.h>
> +#include <linux/kvm_para.h>
>  #include <linux/syscore_ops.h>
>  #include <asm/numa.h>
>
> @@ -24,15 +25,37 @@
>  #define EIOINTC_REG_ISR                0x1800
>  #define EIOINTC_REG_ROUTE      0x1c00
>
> +#define EXTIOI_VIRT_FEATURES           0x40000000
> +#define  EXTIOI_HAS_VIRT_EXTENSION     BIT(0)
> +#define  EXTIOI_HAS_ENABLE_OPTION      BIT(1)
> +#define  EXTIOI_HAS_INT_ENCODE         BIT(2)
> +#define  EXTIOI_HAS_CPU_ENCODE         BIT(3)
> +#define EXTIOI_VIRT_CONFIG             0x40000004
> +#define  EXTIOI_ENABLE                 BIT(1)
> +#define  EXTIOI_ENABLE_INT_ENCODE      BIT(2)
> +#define  EXTIOI_ENABLE_CPU_ENCODE      BIT(3)
> +
>  #define VEC_REG_COUNT          4
>  #define VEC_COUNT_PER_REG      64
>  #define VEC_COUNT              (VEC_REG_COUNT * VEC_COUNT_PER_REG)
>  #define VEC_REG_IDX(irq_id)    ((irq_id) / VEC_COUNT_PER_REG)
>  #define VEC_REG_BIT(irq_id)     ((irq_id) % VEC_COUNT_PER_REG)
>  #define EIOINTC_ALL_ENABLE     0xffffffff
> +#define EIOINTC_ALL_ENABLE_VEC_MASK(vector)    (EIOINTC_ALL_ENABLE & ~BIT(vector & 0x1F))
> +#define EIOINTC_REG_ENABLE_VEC(vector)         (EIOINTC_REG_ENABLE + ((vector >> 5) << 2))
> +#define EIOINTC_USE_CPU_ENCODE                 BIT(0)
>
>  #define MAX_EIO_NODES          (NR_CPUS / CORES_PER_EIO_NODE)
>
> +/*
> + * Routing registers are 32bit, and there is 8-bit route setting for every
> + * interrupt vector. So one Route register contains four vectors routing
> + * information.
> + */
> +#define EIOINTC_REG_ROUTE_VEC(vector)          (EIOINTC_REG_ROUTE + (vector & ~0x03))
> +#define EIOINTC_REG_ROUTE_VEC_SHIFT(vector)    ((vector & 0x03) << 3)
> +#define EIOINTC_REG_ROUTE_VEC_MASK(vector)     (0xff << EIOINTC_REG_ROUTE_VEC_SHIFT(vector))
> +
>  static int nr_pics;
>
>  struct eiointc_priv {
> @@ -42,6 +65,7 @@ struct eiointc_priv {
>         cpumask_t               cpuspan_map;
>         struct fwnode_handle    *domain_handle;
>         struct irq_domain       *eiointc_domain;
> +       int                     flags;
>  };
>
>  static struct eiointc_priv *eiointc_priv[MAX_IO_PICS];
> @@ -57,7 +81,13 @@ static void eiointc_enable(void)
>
>  static int cpu_to_eio_node(int cpu)
>  {
> -       return cpu_logical_map(cpu) / CORES_PER_EIO_NODE;
> +       int cores;
> +
> +       if (kvm_para_has_feature(KVM_FEATURE_VIRT_EXTIOI))
> +               cores = CORES_PER_VEIO_NODE;
> +       else
> +               cores = CORES_PER_EIO_NODE;
> +       return cpu_logical_map(cpu) / cores;
>  }
>
>  #ifdef CONFIG_SMP
> @@ -89,6 +119,17 @@ static void eiointc_set_irq_route(int pos, unsigned int cpu, unsigned int mnode,
>
>  static DEFINE_RAW_SPINLOCK(affinity_lock);
>
> +static void veiointc_set_irq_route(unsigned int vector, unsigned int cpu)
> +{
> +       unsigned long reg = EIOINTC_REG_ROUTE_VEC(vector);
> +       unsigned int data;
> +
> +       data = iocsr_read32(reg);
> +       data &= ~EIOINTC_REG_ROUTE_VEC_MASK(vector);
> +       data |= cpu_logical_map(cpu) << EIOINTC_REG_ROUTE_VEC_SHIFT(vector);
> +       iocsr_write32(data, reg);
> +}
> +
>  static int eiointc_set_irq_affinity(struct irq_data *d, const struct cpumask *affinity, bool force)
>  {
>         unsigned int cpu;
> @@ -105,18 +146,25 @@ static int eiointc_set_irq_affinity(struct irq_data *d, const struct cpumask *af
>         }
>
>         vector = d->hwirq;
> -       regaddr = EIOINTC_REG_ENABLE + ((vector >> 5) << 2);
> -
> -       /* Mask target vector */
> -       csr_any_send(regaddr, EIOINTC_ALL_ENABLE & (~BIT(vector & 0x1F)),
> -                       0x0, priv->node * CORES_PER_EIO_NODE);
> -
> -       /* Set route for target vector */
> -       eiointc_set_irq_route(vector, cpu, priv->node, &priv->node_map);
> -
> -       /* Unmask target vector */
> -       csr_any_send(regaddr, EIOINTC_ALL_ENABLE,
> -                       0x0, priv->node * CORES_PER_EIO_NODE);
> +       regaddr = EIOINTC_REG_ENABLE_VEC(vector);
> +
> +       if (priv->flags & EIOINTC_USE_CPU_ENCODE) {
> +               /* Disable target irq before updating its interrupt routing */
> +               iocsr_write32(EIOINTC_ALL_ENABLE_VEC_MASK(vector), regaddr);
> +               veiointc_set_irq_route(vector, cpu);
> +               iocsr_write32(EIOINTC_ALL_ENABLE, regaddr);
> +       } else {
> +               /* Mask target vector */
> +               csr_any_send(regaddr, EIOINTC_ALL_ENABLE_VEC_MASK(vector),
> +                            0x0, priv->node * CORES_PER_EIO_NODE);
> +
> +               /* Set route for target vector */
> +               eiointc_set_irq_route(vector, cpu, priv->node, &priv->node_map);
> +
> +               /* Unmask target vector */
> +               csr_any_send(regaddr, EIOINTC_ALL_ENABLE,
> +                            0x0, priv->node * CORES_PER_EIO_NODE);
> +       }
>
>         irq_data_update_effective_affinity(d, cpumask_of(cpu));
>
> @@ -140,17 +188,23 @@ static int eiointc_index(int node)
>
>  static int eiointc_router_init(unsigned int cpu)
>  {
> -       int i, bit;
> -       uint32_t data;
> -       uint32_t node = cpu_to_eio_node(cpu);
> -       int index = eiointc_index(node);
> +       int i, bit, cores, index, node;
> +       unsigned int data;
> +
> +       node = cpu_to_eio_node(cpu);
> +       index = eiointc_index(node);
>
>         if (index < 0) {
>                 pr_err("Error: invalid nodemap!\n");
> -               return -1;
> +               return -EINVAL;
>         }
>
> -       if ((cpu_logical_map(cpu) % CORES_PER_EIO_NODE) == 0) {
> +       if (eiointc_priv[index]->flags & EIOINTC_USE_CPU_ENCODE)
> +               cores = CORES_PER_VEIO_NODE;
> +       else
> +               cores = CORES_PER_EIO_NODE;
> +
> +       if ((cpu_logical_map(cpu) % cores) == 0) {
>                 eiointc_enable();
>
>                 for (i = 0; i < eiointc_priv[0]->vec_count / 32; i++) {
> @@ -166,7 +220,9 @@ static int eiointc_router_init(unsigned int cpu)
>
>                 for (i = 0; i < eiointc_priv[0]->vec_count / 4; i++) {
>                         /* Route to Node-0 Core-0 */
> -                       if (index == 0)
> +                       if (eiointc_priv[index]->flags & EIOINTC_USE_CPU_ENCODE)
> +                               bit = cpu_logical_map(0);
> +                       else if (index == 0)
>                                 bit = BIT(cpu_logical_map(0));
>                         else
>                                 bit = (eiointc_priv[index]->node << 4) | 1;
> @@ -370,7 +426,7 @@ static int __init acpi_cascade_irqdomain_init(void)
>  static int __init eiointc_init(struct eiointc_priv *priv, int parent_irq,
>                                u64 node_map)
>  {
> -       int i;
> +       int i, val;
>
>         node_map = node_map ? node_map : -1ULL;
>         for_each_possible_cpu(i) {
> @@ -390,6 +446,20 @@ static int __init eiointc_init(struct eiointc_priv *priv, int parent_irq,
>                 return -ENOMEM;
>         }
>
> +       if (kvm_para_has_feature(KVM_FEATURE_VIRT_EXTIOI)) {
> +               val = iocsr_read32(EXTIOI_VIRT_FEATURES);
> +               if (val & EXTIOI_HAS_CPU_ENCODE) {
> +                       /*
> +                        * With EXTIOI_ENABLE_CPU_ENCODE set, interrupt can
> +                        * route to 256 CPUs
> +                        */
> +                       val = iocsr_read32(EXTIOI_VIRT_CONFIG);
> +                       val |= EXTIOI_ENABLE_CPU_ENCODE;
> +                       iocsr_write32(val, EXTIOI_VIRT_CONFIG);
> +                       priv->flags = EIOINTC_USE_CPU_ENCODE;
> +               }
> +       }
> +
>         eiointc_priv[nr_pics++] = priv;
>         eiointc_router_init(0);
>         irq_set_chained_handler_and_data(parent_irq, eiointc_irq_dispatch, priv);
> --
> 2.39.3
>