Re: [Qemu-devel] [PATCH v6 5/8] hw/intc/arm_gicv3_its: Implement support for in-kernel ITS emulation

[Peter Maydell]

On 9 September 2016 at 18:30, Eric Auger <address@hidden> wrote:
> From: Pavel Fedin <address@hidden>
>
> The ITS control frame is in-kernel emulated while accesses to the
> GITS_TRANSLATER are mediated through the KVM_SIGNAL_MSI ioctl (MSI
> direct MSI injection advertised by the CAP_SIGNAL_MSI capability)
>
> the kvm_gsi_direct_mapping is explicitly set to false to emphasize the
> difference with GICv2M. Direct mapping cannot work with ITS since
> the content of the MSI data is not the target interrupt ID but an
> eventd id.
>
> GSI routing is advertised (kvm_gsi_routing_allowed) as well as
> msi/irqfd signaling (kvm_msi_via_irqfd_allowed).
>
> A machine init done notifier still is used to compute the MSI frame
> (GITS_TRANSLATER) GPA, which is passed through KVM_SIGNAL_MSI ioctl.
>
> Signed-off-by: Pavel Fedin <address@hidden>
> Signed-off-by: Eric Auger <address@hidden>
>
> ---
> v5 -> v6:
> - now the kernel ITS init sequence has changed let's use the
>   kvm_arm_register_device to set the CTRL frame base address
> - use extract64()
> - add migration blocker
> - remove kvm_gsi_routing_allowed setting which is set in GICv3
>   KVM device realize
> - add migration_blocker
>
> v3 -> v4:
> - include "qemu/osdep.h" and  "qapi/error.h"
> - rename KVM_VGIC_V3_ADDR_TYPE_ITS into KVM_VGIC_ITS_ADDR_TYPE
> - reword commit message
> - change kvm_msi_via_irqfd_allowed definition (attached to irqfd dynamic
>   availability + MSI controller availability)
> - create the ITS KVM device (previously abstracted by the GICv3 KVM device)
> - init sequence changed
> - absolute GITS_TRANSLATER GPA stored
>
> Signed-off-by: Eric Auger <address@hidden>
> ---
>  hw/intc/Makefile.objs       |   1 +
>  hw/intc/arm_gicv3_its_kvm.c | 136 
> ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 137 insertions(+)
>  create mode 100644 hw/intc/arm_gicv3_its_kvm.c
>
> diff --git a/hw/intc/Makefile.objs b/hw/intc/Makefile.objs
> index 23a39f7..9cca280 100644
> --- a/hw/intc/Makefile.objs
> +++ b/hw/intc/Makefile.objs
> @@ -22,6 +22,7 @@ common-obj-$(CONFIG_OPENPIC) += openpic.o
>  obj-$(CONFIG_APIC) += apic.o apic_common.o
>  obj-$(CONFIG_ARM_GIC_KVM) += arm_gic_kvm.o
>  obj-$(call land,$(CONFIG_ARM_GIC_KVM),$(TARGET_AARCH64)) += arm_gicv3_kvm.o
> +obj-$(call land,$(CONFIG_ARM_GIC_KVM),$(TARGET_AARCH64)) += 
> arm_gicv3_its_kvm.o
>  obj-$(CONFIG_STELLARIS) += armv7m_nvic.o
>  obj-$(CONFIG_EXYNOS4) += exynos4210_gic.o exynos4210_combiner.o
>  obj-$(CONFIG_GRLIB) += grlib_irqmp.o
> diff --git a/hw/intc/arm_gicv3_its_kvm.c b/hw/intc/arm_gicv3_its_kvm.c
> new file mode 100644
> index 0000000..b9d10dc
> --- /dev/null
> +++ b/hw/intc/arm_gicv3_its_kvm.c
> @@ -0,0 +1,136 @@
> +/*
> + * KVM-based ITS implementation for a GICv3-based system
> + *
> + * Copyright (c) 2015 Samsung Electronics Co., Ltd.
> + * Written by Pavel Fedin <address@hidden>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see 
> <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "hw/intc/arm_gicv3_its_common.h"
> +#include "sysemu/sysemu.h"
> +#include "sysemu/kvm.h"
> +#include "kvm_arm.h"
> +#include "migration/migration.h"
> +
> +#define TYPE_KVM_ARM_ITS "arm-its-kvm"
> +#define KVM_ARM_ITS(obj) OBJECT_CHECK(GICv3ITSState, (obj), TYPE_KVM_ARM_ITS)
> +
> +static int kvm_its_send_msi(GICv3ITSState *s, uint32_t value, uint16_t devid)
> +{
> +    struct kvm_msi msi;
> +
> +    msi.address_lo = extract64(s->gits_translater_gpa, 0, 32);
> +    msi.address_hi = extract64(s->gits_translater_gpa, 32, 32);
> +    msi.data = le32_to_cpu(value);
> +    msi.flags = KVM_MSI_VALID_DEVID;
> +    msi.devid = devid;
> +    memset(msi.pad, 0, sizeof(msi.pad));
> +
> +    return kvm_vm_ioctl(kvm_state, KVM_SIGNAL_MSI, &msi);
> +}
> +
> +typedef struct ItsInitNotifierParams {
> +    Notifier notifier;
> +    GICv3ITSState *s;
> +} ItsInitNotifierParams;
> +
> +/* this notifier computes and stores the ITS MSI frame GPA */
> +static void its_notify(Notifier *notifier, void *data)
> +{
> +    ItsInitNotifierParams *p = DO_UPCAST(ItsInitNotifierParams,
> +                                         notifier, notifier);
> +    GICv3ITSState *s = p->s;
> +    MemoryRegion *mr = &s->iomem_its_translation;
> +    MemoryRegionSection mrs;
> +    uint64_t addr;
> +
> +    mrs = memory_region_find(mr, 0, 1);
> +    addr = mrs.offset_within_address_space;
> +    s->gits_translater_gpa = addr + 0x40;

This leaks a memory region reference.

Also, I think it would be simpler to just have kvm_its_send_msi() do

   if (unlikely(!s->translater_gpa_known)) {
       s->gits_translater_gpa = ...;
       s->translater_gpa_known = true;
   }

rather than messing around with a machine-init-done notifier.

> +}
> +
> +static void kvm_arm_its_realize(DeviceState *dev, Error **errp)
> +{
> +    GICv3ITSState *s = ARM_GICV3_ITS_COMMON(dev);
> +    ItsInitNotifierParams *p = g_new(ItsInitNotifierParams, 1);
> +
> +    s->dev_fd = kvm_create_device(kvm_state, KVM_DEV_TYPE_ARM_VGIC_ITS, 
> false);
> +    if (s->dev_fd < 0) {
> +        error_setg_errno(errp, -s->dev_fd, "error creating in-kernel ITS");
> +        return;
> +    }
> +
> +    /* explicit init if the ITS */

"of the"

> +    kvm_device_access(s->dev_fd, KVM_DEV_ARM_VGIC_GRP_CTRL,
> +                      KVM_DEV_ARM_VGIC_CTRL_INIT, NULL, true);
> +
> +    /* register the base address */
> +    kvm_arm_register_device(&s->iomem_its_cntrl, -1, 
> KVM_DEV_ARM_VGIC_GRP_ADDR,
> +                            KVM_VGIC_ITS_ADDR_TYPE, s->dev_fd);
> +
> +    gicv3_its_init_mmio(s, NULL);
> +
> +    p->notifier.notify = its_notify;
> +    p->s = s;
> +    qemu_add_machine_init_done_notifier(&p->notifier);
> +
> +    /*
> +     * Block migration of a KVM GICv3 ITS device: the API for saving and
> +     * restoring the state in the kernel is not yet available
> +     */
> +    error_setg(&s->migration_blocker, "vITS migration is not implemented");
> +    migrate_add_blocker(s->migration_blocker);
> +
> +    kvm_msi_use_devid = true;
> +    kvm_gsi_direct_mapping = false;
> +    kvm_msi_via_irqfd_allowed = kvm_irqfds_enabled();
> +}
> +
> +static void kvm_arm_its_init(Object *obj)
> +{
> +    GICv3ITSState *s = KVM_ARM_ITS(obj);
> +
> +    object_property_add_link(obj, "parent-gicv3",
> +                             "kvm-arm-gicv3", (Object **)&s->gicv3,
> +                             object_property_allow_set_link,
> +                             OBJ_PROP_LINK_UNREF_ON_RELEASE,
> +                             &error_abort);
> +}
> +
> +static void kvm_arm_its_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    GICv3ITSCommonClass *icc = ARM_GICV3_ITS_COMMON_CLASS(klass);
> +
> +    dc->realize = kvm_arm_its_realize;
> +    icc->send_msi = kvm_its_send_msi;
> +}
> +
> +static const TypeInfo kvm_arm_its_info = {
> +    .name = TYPE_KVM_ARM_ITS,
> +    .parent = TYPE_ARM_GICV3_ITS_COMMON,
> +    .instance_size = sizeof(GICv3ITSState),
> +    .instance_init = kvm_arm_its_init,
> +    .class_init = kvm_arm_its_class_init,
> +};
> +
> +static void kvm_arm_its_register_types(void)
> +{
> +    type_register_static(&kvm_arm_its_info);
> +}
> +
> +type_init(kvm_arm_its_register_types)
> --
> 2.5.5

thanks
-- PMM