xics-kvm: Support for in-kernel XICS interrupt controller

Recent (host) kernels support emulating the PAPR defined "XICS" interrupt
controller system within KVM.  This patch allows qemu to initialize and
configure the in-kernel XICS, and keep its state in sync with qemu's XICS
state as necessary.

This should give considerable performance improvements.  e.g. on a simple
IPI ping-pong test between hardware threads, using qemu XICS gives us
around 5,000 irqs/second, whereas the in-kernel XICS gives us around
70,000 irqs/s on the same hardware configuration.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
[Mike Qiu <qiudayu@linux.vnet.ibm.com>: fixed mistype which caused ics_set_kvm_state() to fail]
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

default-configs/ppc64-softmmu.mak

@@ -46,6 +46,7 @@ CONFIG_E500=y
 CONFIG_OPENPIC_KVM=$(and $(CONFIG_E500),$(CONFIG_KVM))
 # For pSeries
 CONFIG_XICS=$(CONFIG_PSERIES)
+CONFIG_XICS_KVM=$(and $(CONFIG_PSERIES),$(CONFIG_KVM))
 # For PReP
 CONFIG_I82378=y
 CONFIG_I8259=y

hw/intc/Makefile.objs

@@ -23,3 +23,4 @@ obj-$(CONFIG_OMAP) += omap_intc.o
 obj-$(CONFIG_OPENPIC_KVM) += openpic_kvm.o
 obj-$(CONFIG_SH4) += sh_intc.o
 obj-$(CONFIG_XICS) += xics.o
+obj-$(CONFIG_XICS_KVM) += xics_kvm.o

hw/intc/xics_kvm.c

@@ -0,0 +1,488 @@
+/*
+ * QEMU PowerPC pSeries Logical Partition (aka sPAPR) hardware System Emulator
+ *
+ * PAPR Virtualized Interrupt System, aka ICS/ICP aka xics, in-kernel emulation
+ *
+ * Copyright (c) 2013 David Gibson, IBM Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#include "hw/hw.h"
+#include "trace.h"
+#include "hw/ppc/spapr.h"
+#include "hw/ppc/xics.h"
+#include "kvm_ppc.h"
+#include "qemu/config-file.h"
+#include "qemu/error-report.h"
+
+#include <sys/ioctl.h>
+
+typedef struct KVMXICSState {
+    XICSState parent_obj;
+
+    uint32_t set_xive_token;
+    uint32_t get_xive_token;
+    uint32_t int_off_token;
+    uint32_t int_on_token;
+    int kernel_xics_fd;
+} KVMXICSState;
+
+/*
+ * ICP-KVM
+ */
+static void icp_get_kvm_state(ICPState *ss)
+{
+    uint64_t state;
+    struct kvm_one_reg reg = {
+        .id = KVM_REG_PPC_ICP_STATE,
+        .addr = (uintptr_t)&state,
+    };
+    int ret;
+
+    /* ICP for this CPU thread is not in use, exiting */
+    if (!ss->cs) {
+        return;
+    }
+
+    ret = kvm_vcpu_ioctl(ss->cs, KVM_GET_ONE_REG, &reg);
+    if (ret != 0) {
+        error_report("Unable to retrieve KVM interrupt controller state"
+                " for CPU %d: %s", ss->cs->cpu_index, strerror(errno));
+        exit(1);
+    }
+
+    ss->xirr = state >> KVM_REG_PPC_ICP_XISR_SHIFT;
+    ss->mfrr = (state >> KVM_REG_PPC_ICP_MFRR_SHIFT)
+        & KVM_REG_PPC_ICP_MFRR_MASK;
+    ss->pending_priority = (state >> KVM_REG_PPC_ICP_PPRI_SHIFT)
+        & KVM_REG_PPC_ICP_PPRI_MASK;
+}
+
+static int icp_set_kvm_state(ICPState *ss, int version_id)
+{
+    uint64_t state;
+    struct kvm_one_reg reg = {
+        .id = KVM_REG_PPC_ICP_STATE,
+        .addr = (uintptr_t)&state,
+    };
+    int ret;
+
+    /* ICP for this CPU thread is not in use, exiting */
+    if (!ss->cs) {
+        return 0;
+    }
+
+    state = ((uint64_t)ss->xirr << KVM_REG_PPC_ICP_XISR_SHIFT)
+        | ((uint64_t)ss->mfrr << KVM_REG_PPC_ICP_MFRR_SHIFT)
+        | ((uint64_t)ss->pending_priority << KVM_REG_PPC_ICP_PPRI_SHIFT);
+
+    ret = kvm_vcpu_ioctl(ss->cs, KVM_SET_ONE_REG, &reg);
+    if (ret != 0) {
+        error_report("Unable to restore KVM interrupt controller state (0x%"
+                PRIx64 ") for CPU %d: %s", state, ss->cs->cpu_index,
+                strerror(errno));
+        return ret;
+    }
+
+    return 0;
+}
+
+static void icp_kvm_reset(DeviceState *dev)
+{
+    ICPState *icp = ICP(dev);
+
+    icp->xirr = 0;
+    icp->pending_priority = 0xff;
+    icp->mfrr = 0xff;
+
+    /* Make all outputs are deasserted */
+    qemu_set_irq(icp->output, 0);
+
+    icp_set_kvm_state(icp, 1);
+}
+
+static void icp_kvm_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    ICPStateClass *icpc = ICP_CLASS(klass);
+
+    dc->reset = icp_kvm_reset;
+    icpc->pre_save = icp_get_kvm_state;
+    icpc->post_load = icp_set_kvm_state;
+}
+
+static const TypeInfo icp_kvm_info = {
+    .name = TYPE_KVM_ICP,
+    .parent = TYPE_ICP,
+    .instance_size = sizeof(ICPState),
+    .class_init = icp_kvm_class_init,
+    .class_size = sizeof(ICPStateClass),
+};
+
+/*
+ * ICS-KVM
+ */
+static void ics_get_kvm_state(ICSState *ics)
+{
+    KVMXICSState *icpkvm = KVM_XICS(ics->icp);
+    uint64_t state;
+    struct kvm_device_attr attr = {
+        .flags = 0,
+        .group = KVM_DEV_XICS_GRP_SOURCES,
+        .addr = (uint64_t)(uintptr_t)&state,
+    };
+    int i;
+
+    for (i = 0; i < ics->nr_irqs; i++) {
+        ICSIRQState *irq = &ics->irqs[i];
+        int ret;
+
+        attr.attr = i + ics->offset;
+
+        ret = ioctl(icpkvm->kernel_xics_fd, KVM_GET_DEVICE_ATTR, &attr);
+        if (ret != 0) {
+            error_report("Unable to retrieve KVM interrupt controller state"
+                    " for IRQ %d: %s", i + ics->offset, strerror(errno));
+            exit(1);
+        }
+
+        irq->server = state & KVM_XICS_DESTINATION_MASK;
+        irq->saved_priority = (state >> KVM_XICS_PRIORITY_SHIFT)
+            & KVM_XICS_PRIORITY_MASK;
+        /*
+         * To be consistent with the software emulation in xics.c, we
+         * split out the masked state + priority that we get from the
+         * kernel into 'current priority' (0xff if masked) and
+         * 'saved priority' (if masked, this is the priority the
+         * interrupt had before it was masked).  Masking and unmasking
+         * are done with the ibm,int-off and ibm,int-on RTAS calls.
+         */
+        if (state & KVM_XICS_MASKED) {
+            irq->priority = 0xff;
+        } else {
+            irq->priority = irq->saved_priority;
+        }
+
+        if (state & KVM_XICS_PENDING) {
+            if (state & KVM_XICS_LEVEL_SENSITIVE) {
+                irq->status |= XICS_STATUS_ASSERTED;
+            } else {
+                /*
+                 * A pending edge-triggered interrupt (or MSI)
+                 * must have been rejected previously when we
+                 * first detected it and tried to deliver it,
+                 * so mark it as pending and previously rejected
+                 * for consistency with how xics.c works.
+                 */
+                irq->status |= XICS_STATUS_MASKED_PENDING
+                    | XICS_STATUS_REJECTED;
+            }
+        }
+    }
+}
+
+static int ics_set_kvm_state(ICSState *ics, int version_id)
+{
+    KVMXICSState *icpkvm = KVM_XICS(ics->icp);
+    uint64_t state;
+    struct kvm_device_attr attr = {
+        .flags = 0,
+        .group = KVM_DEV_XICS_GRP_SOURCES,
+        .addr = (uint64_t)(uintptr_t)&state,
+    };
+    int i;
+
+    for (i = 0; i < ics->nr_irqs; i++) {
+        ICSIRQState *irq = &ics->irqs[i];
+        int ret;
+
+        attr.attr = i + ics->offset;
+
+        state = irq->server;
+        state |= (uint64_t)(irq->saved_priority & KVM_XICS_PRIORITY_MASK)
+            << KVM_XICS_PRIORITY_SHIFT;
+        if (irq->priority != irq->saved_priority) {
+            assert(irq->priority == 0xff);
+            state |= KVM_XICS_MASKED;
+        }
+
+        if (ics->islsi[i]) {
+            state |= KVM_XICS_LEVEL_SENSITIVE;
+            if (irq->status & XICS_STATUS_ASSERTED) {
+                state |= KVM_XICS_PENDING;
+            }
+        } else {
+            if (irq->status & XICS_STATUS_MASKED_PENDING) {
+                state |= KVM_XICS_PENDING;
+            }
+        }
+
+        ret = ioctl(icpkvm->kernel_xics_fd, KVM_SET_DEVICE_ATTR, &attr);
+        if (ret != 0) {
+            error_report("Unable to restore KVM interrupt controller state"
+                    " for IRQs %d: %s", i + ics->offset, strerror(errno));
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
+static void ics_kvm_set_irq(void *opaque, int srcno, int val)
+{
+    ICSState *ics = opaque;
+    struct kvm_irq_level args;
+    int rc;
+
+    args.irq = srcno + ics->offset;
+    if (!ics->islsi[srcno]) {
+        if (!val) {
+            return;
+        }
+        args.level = KVM_INTERRUPT_SET;
+    } else {
+        args.level = val ? KVM_INTERRUPT_SET_LEVEL : KVM_INTERRUPT_UNSET;
+    }
+    rc = kvm_vm_ioctl(kvm_state, KVM_IRQ_LINE, &args);
+    if (rc < 0) {
+        perror("kvm_irq_line");
+    }
+}
+
+static void ics_kvm_reset(DeviceState *dev)
+{
+    ics_set_kvm_state(ICS(dev), 1);
+}
+
+static void ics_kvm_realize(DeviceState *dev, Error **errp)
+{
+    ICSState *ics = ICS(dev);
+
+    if (!ics->nr_irqs) {
+        error_setg(errp, "Number of interrupts needs to be greater 0");
+        return;
+    }
+    ics->irqs = g_malloc0(ics->nr_irqs * sizeof(ICSIRQState));
+    ics->islsi = g_malloc0(ics->nr_irqs * sizeof(bool));
+    ics->qirqs = qemu_allocate_irqs(ics_kvm_set_irq, ics, ics->nr_irqs);
+}
+
+static void ics_kvm_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    ICSStateClass *icsc = ICS_CLASS(klass);
+
+    dc->realize = ics_kvm_realize;
+    dc->reset = ics_kvm_reset;
+    icsc->pre_save = ics_get_kvm_state;
+    icsc->post_load = ics_set_kvm_state;
+}
+
+static const TypeInfo ics_kvm_info = {
+    .name = TYPE_KVM_ICS,
+    .parent = TYPE_ICS,
+    .instance_size = sizeof(ICSState),
+    .class_init = ics_kvm_class_init,
+};
+
+/*
+ * XICS-KVM
+ */
+static void xics_kvm_cpu_setup(XICSState *icp, PowerPCCPU *cpu)
+{
+    CPUState *cs;
+    ICPState *ss;
+    KVMXICSState *icpkvm = KVM_XICS(icp);
+
+    cs = CPU(cpu);
+    ss = &icp->ss[cs->cpu_index];
+
+    assert(cs->cpu_index < icp->nr_servers);
+    if (icpkvm->kernel_xics_fd == -1) {
+        abort();
+    }
+
+    if (icpkvm->kernel_xics_fd != -1) {
+        int ret;
+        struct kvm_enable_cap xics_enable_cap = {
+            .cap = KVM_CAP_IRQ_XICS,
+            .flags = 0,
+            .args = {icpkvm->kernel_xics_fd, cs->cpu_index, 0, 0},
+        };
+
+        ss->cs = cs;
+
+        ret = kvm_vcpu_ioctl(ss->cs, KVM_ENABLE_CAP, &xics_enable_cap);
+        if (ret < 0) {
+            error_report("Unable to connect CPU%d to kernel XICS: %s",
+                    cs->cpu_index, strerror(errno));
+            exit(1);
+        }
+    }
+}
+
+static void xics_kvm_set_nr_irqs(XICSState *icp, uint32_t nr_irqs, Error **errp)
+{
+    icp->nr_irqs = icp->ics->nr_irqs = nr_irqs;
+}
+
+static void xics_kvm_set_nr_servers(XICSState *icp, uint32_t nr_servers,
+                                    Error **errp)
+{
+    int i;
+
+    icp->nr_servers = nr_servers;
+
+    icp->ss = g_malloc0(icp->nr_servers*sizeof(ICPState));
+    for (i = 0; i < icp->nr_servers; i++) {
+        char buffer[32];
+        object_initialize(&icp->ss[i], sizeof(icp->ss[i]), TYPE_KVM_ICP);
+        snprintf(buffer, sizeof(buffer), "icp[%d]", i);
+        object_property_add_child(OBJECT(icp), buffer, OBJECT(&icp->ss[i]),
+                                  errp);
+    }
+}
+
+static void rtas_dummy(PowerPCCPU *cpu, sPAPREnvironment *spapr,
+                       uint32_t token,
+                       uint32_t nargs, target_ulong args,
+                       uint32_t nret, target_ulong rets)
+{
+    error_report("pseries: %s must never be called for in-kernel XICS",
+                 __func__);
+}
+
+static void xics_kvm_realize(DeviceState *dev, Error **errp)
+{
+    KVMXICSState *icpkvm = KVM_XICS(dev);
+    XICSState *icp = XICS_COMMON(dev);
+    int i, rc;
+    Error *error = NULL;
+    struct kvm_create_device xics_create_device = {
+        .type = KVM_DEV_TYPE_XICS,
+        .flags = 0,
+    };
+
+    if (!kvm_enabled() || !kvm_check_extension(kvm_state, KVM_CAP_IRQ_XICS)) {
+        error_setg(errp,
+                   "KVM and IRQ_XICS capability must be present for in-kernel XICS");
+        goto fail;
+    }
+
+    icpkvm->set_xive_token = spapr_rtas_register("ibm,set-xive", rtas_dummy);
+    icpkvm->get_xive_token = spapr_rtas_register("ibm,get-xive", rtas_dummy);
+    icpkvm->int_off_token = spapr_rtas_register("ibm,int-off", rtas_dummy);
+    icpkvm->int_on_token = spapr_rtas_register("ibm,int-on", rtas_dummy);
+
+    rc = kvmppc_define_rtas_kernel_token(icpkvm->set_xive_token,
+                                         "ibm,set-xive");
+    if (rc < 0) {
+        error_setg(errp, "kvmppc_define_rtas_kernel_token: ibm,set-xive");
+        goto fail;
+    }
+
+    rc = kvmppc_define_rtas_kernel_token(icpkvm->get_xive_token,
+                                         "ibm,get-xive");
+    if (rc < 0) {
+        error_setg(errp, "kvmppc_define_rtas_kernel_token: ibm,get-xive");
+        goto fail;
+    }
+
+    rc = kvmppc_define_rtas_kernel_token(icpkvm->int_on_token, "ibm,int-on");
+    if (rc < 0) {
+        error_setg(errp, "kvmppc_define_rtas_kernel_token: ibm,int-on");
+        goto fail;
+    }
+
+    rc = kvmppc_define_rtas_kernel_token(icpkvm->int_off_token, "ibm,int-off");
+    if (rc < 0) {
+        error_setg(errp, "kvmppc_define_rtas_kernel_token: ibm,int-off");
+        goto fail;
+    }
+
+    /* Create the kernel ICP */
+    rc = kvm_vm_ioctl(kvm_state, KVM_CREATE_DEVICE, &xics_create_device);
+    if (rc < 0) {
+        error_setg_errno(errp, -rc, "Error on KVM_CREATE_DEVICE for XICS");
+        goto fail;
+    }
+
+    icpkvm->kernel_xics_fd = xics_create_device.fd;
+
+    object_property_set_bool(OBJECT(icp->ics), true, "realized", &error);
+    if (error) {
+        error_propagate(errp, error);
+        goto fail;
+    }
+
+    assert(icp->nr_servers);
+    for (i = 0; i < icp->nr_servers; i++) {
+        object_property_set_bool(OBJECT(&icp->ss[i]), true, "realized", &error);
+        if (error) {
+            error_propagate(errp, error);
+            goto fail;
+        }
+    }
+    return;
+
+fail:
+    kvmppc_define_rtas_kernel_token(0, "ibm,set-xive");
+    kvmppc_define_rtas_kernel_token(0, "ibm,get-xive");
+    kvmppc_define_rtas_kernel_token(0, "ibm,int-on");
+    kvmppc_define_rtas_kernel_token(0, "ibm,int-off");
+}
+
+static void xics_kvm_initfn(Object *obj)
+{
+    XICSState *xics = XICS_COMMON(obj);
+
+    xics->ics = ICS(object_new(TYPE_KVM_ICS));
+    object_property_add_child(obj, "ics", OBJECT(xics->ics), NULL);
+    xics->ics->icp = xics;
+}
+
+static void xics_kvm_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+    XICSStateClass *xsc = XICS_COMMON_CLASS(oc);
+
+    dc->realize = xics_kvm_realize;
+    xsc->cpu_setup = xics_kvm_cpu_setup;
+    xsc->set_nr_irqs = xics_kvm_set_nr_irqs;
+    xsc->set_nr_servers = xics_kvm_set_nr_servers;
+}
+
+static const TypeInfo xics_kvm_info = {
+    .name          = TYPE_KVM_XICS,
+    .parent        = TYPE_XICS_COMMON,
+    .instance_size = sizeof(KVMXICSState),
+    .class_init    = xics_kvm_class_init,
+    .instance_init = xics_kvm_initfn,
+};
+
+static void xics_kvm_register_types(void)
+{
+    type_register_static(&xics_kvm_info);
+    type_register_static(&ics_kvm_info);
+    type_register_static(&icp_kvm_info);
+}
+
+type_init(xics_kvm_register_types)

hw/ppc/spapr.c

@@ -168,7 +168,26 @@ static XICSState *xics_system_init(int nr_servers, int nr_irqs)
 {
     XICSState *icp = NULL;
 
+    if (kvm_enabled()) {
+        QemuOpts *machine_opts = qemu_get_machine_opts();
+        bool irqchip_allowed = qemu_opt_get_bool(machine_opts,
+                                                "kernel_irqchip", true);
+        bool irqchip_required = qemu_opt_get_bool(machine_opts,
+                                                  "kernel_irqchip", false);
+        if (irqchip_allowed) {
+            icp = try_create_xics(TYPE_KVM_XICS, nr_servers, nr_irqs);
+        }
+
+        if (irqchip_required && !icp) {
+            perror("Failed to create in-kernel XICS\n");
+            abort();
+        }
+    }
+
+    if (!icp) {
         icp = try_create_xics(TYPE_XICS, nr_servers, nr_irqs);
+    }
+
     if (!icp) {
         perror("Failed to create XICS\n");
         abort();

include/hw/ppc/xics.h

@@ -35,6 +35,9 @@
 #define TYPE_XICS "xics"
 #define XICS(obj) OBJECT_CHECK(XICSState, (obj), TYPE_XICS)
 
+#define TYPE_KVM_XICS "xics-kvm"
+#define KVM_XICS(obj) OBJECT_CHECK(KVMXICSState, (obj), TYPE_KVM_XICS)
+
 #define XICS_COMMON_CLASS(klass) \
      OBJECT_CLASS_CHECK(XICSStateClass, (klass), TYPE_XICS_COMMON)
 #define XICS_CLASS(klass) \
@@ -82,6 +85,9 @@ struct XICSState {
 #define TYPE_ICP "icp"
 #define ICP(obj) OBJECT_CHECK(ICPState, (obj), TYPE_ICP)
 
+#define TYPE_KVM_ICP "icp-kvm"
+#define KVM_ICP(obj) OBJECT_CHECK(ICPState, (obj), TYPE_KVM_ICP)
+
 #define ICP_CLASS(klass) \
      OBJECT_CLASS_CHECK(ICPStateClass, (klass), TYPE_ICP)
 #define ICP_GET_CLASS(obj) \
@@ -98,6 +104,7 @@ struct ICPState {
     /*< private >*/
     DeviceState parent_obj;
     /*< public >*/
+    CPUState *cs;
     uint32_t xirr;
     uint8_t pending_priority;
     uint8_t mfrr;
@@ -107,6 +114,9 @@ struct ICPState {
 #define TYPE_ICS "ics"
 #define ICS(obj) OBJECT_CHECK(ICSState, (obj), TYPE_ICS)
 
+#define TYPE_KVM_ICS "icskvm"
+#define KVM_ICS(obj) OBJECT_CHECK(ICSState, (obj), TYPE_KVM_ICS)
+
 #define ICS_CLASS(klass) \
      OBJECT_CLASS_CHECK(ICSStateClass, (klass), TYPE_ICS)
 #define ICS_GET_CLASS(obj) \