Re: [Qemu-devel] [PATCH v5 33/36] spapr: introduce routines to delete the KVM IRQ device

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Nov 16, 2018 at 11:57:26AM +0100, Cédric Le Goater wrote:
> If a new interrupt mode is chosen by CAS, the machine generates a
> reset to reconfigure. At this point, the connection with the previous
> KVM device needs to be closed and a new connection needs to opened
> with the KVM device operating the chosen interrupt mode.
> 
> New routines are introduced to destroy the XICS and XIVE KVM
> devices. They make use of a new KVM device ioctl which destroys the
> device and also disconnects the IRQ presenters from the VCPUs.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  include/hw/ppc/spapr_xive.h |  1 +
>  include/hw/ppc/xics.h       |  1 +
>  linux-headers/linux/kvm.h   |  2 ++
>  hw/intc/spapr_xive_kvm.c    | 54 +++++++++++++++++++++++++++++++++++
>  hw/intc/xics_kvm.c          | 57 +++++++++++++++++++++++++++++++++++++
>  5 files changed, 115 insertions(+)
> 
> diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
> index 1d134a681326..c913c0aed08a 100644
> --- a/include/hw/ppc/spapr_xive.h
> +++ b/include/hw/ppc/spapr_xive.h
> @@ -108,5 +108,6 @@ void spapr_xive_mmio_map(sPAPRXive *xive);
>  #define XIVE_TCTX_KVM(obj)   OBJECT_CHECK(XiveTCTX, (obj), TYPE_XIVE_TCTX_KVM)
>  
>  void spapr_xive_kvm_init(sPAPRXive *xive, Error **errp);
> +void spapr_xive_kvm_fini(sPAPRXive *xive, Error **errp);
>  
>  #endif /* PPC_SPAPR_XIVE_H */
> diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
> index 9958443d1984..a5468c6eb6e3 100644
> --- a/include/hw/ppc/xics.h
> +++ b/include/hw/ppc/xics.h
> @@ -205,6 +205,7 @@ void icp_resend(ICPState *ss);
>  typedef struct sPAPRMachineState sPAPRMachineState;
>  
>  int xics_kvm_init(sPAPRMachineState *spapr, Error **errp);
> +int xics_kvm_fini(sPAPRMachineState *spapr, Error **errp);
>  void xics_spapr_init(sPAPRMachineState *spapr);
>  
>  Object *icp_create(Object *cpu, const char *type, XICSFabric *xi,
> diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
> index 59fa8d8d7f39..b7a74c58d0db 100644
> --- a/linux-headers/linux/kvm.h
> +++ b/linux-headers/linux/kvm.h

linux-headers updates separate.

> @@ -1309,6 +1309,8 @@ struct kvm_s390_ucas_mapping {
>  #define KVM_GET_DEVICE_ATTR	  _IOW(KVMIO,  0xe2, struct kvm_device_attr)
>  #define KVM_HAS_DEVICE_ATTR	  _IOW(KVMIO,  0xe3, struct kvm_device_attr)
>  
> +#define KVM_DESTROY_DEVICE	  _IOWR(KVMIO,  0xf0, struct kvm_create_device)
> +
>  /*
>   * ioctls for vcpu fds
>   */
> diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
> index cb2aa6e81274..0672d8bcbc6b 100644
> --- a/hw/intc/spapr_xive_kvm.c
> +++ b/hw/intc/spapr_xive_kvm.c
> @@ -55,6 +55,16 @@ static void kvm_cpu_enable(CPUState *cs)
>      QLIST_INSERT_HEAD(&kvm_enabled_cpus, enabled_cpu, node);
>  }
>  
> +static void kvm_cpu_disable_all(void)
> +{
> +    KVMEnabledCPU *enabled_cpu, *next;
> +
> +    QLIST_FOREACH_SAFE(enabled_cpu, &kvm_enabled_cpus, node, next) {
> +        QLIST_REMOVE(enabled_cpu, node);
> +        g_free(enabled_cpu);
> +    }
> +}
> +
>  /*
>   * XIVE Thread Interrupt Management context (KVM)
>   */
> @@ -864,6 +874,50 @@ void spapr_xive_kvm_init(sPAPRXive *xive, Error **errp)
>      kvm_gsi_direct_mapping = true;
>  }
>  
> +void spapr_xive_kvm_fini(sPAPRXive *xive, Error **errp)
> +{
> +    XiveSource *xsrc = &xive->source;
> +    struct kvm_create_device xive_destroy_device = {
> +        .fd = xive->fd,
> +        .type = KVM_DEV_TYPE_XIVE,
> +        .flags = 0,
> +    };
> +    size_t esb_len = (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
> +    int rc;
> +
> +    /* The KVM XIVE device is not in use */
> +    if (xive->fd == -1) {
> +        return;
> +    }
> +
> +    if (!kvm_enabled() || !kvmppc_has_cap_xive()) {
> +        error_setg(errp,
> +                   "IRQ_XIVE capability must be present for KVM XIVE device");
> +        return;

If we're here, xive->fd, checked above, definitely shouldn't have been
valid, so you can just assert().

> +    }
> +
> +    /* Clear the KVM mapping */
> +    sysbus_mmio_unmap(SYS_BUS_DEVICE(xsrc), 0);
> +    munmap(xsrc->esb_mmap, esb_len);
> +    sysbus_mmio_unmap(SYS_BUS_DEVICE(xive), 0);
> +    munmap(xive->tm_mmap, 4ull << TM_SHIFT);
> +
> +    /* Destroy the KVM device. This also clears the VCPU presenters */
> +    rc = kvm_vm_ioctl(kvm_state, KVM_DESTROY_DEVICE, &xive_destroy_device);
> +    if (rc < 0) {
> +        error_setg_errno(errp, -rc, "Error on KVM_DESTROY_DEVICE for XIVE");
> +    }
> +    close(xive->fd);
> +    xive->fd = -1;
> +
> +    kvm_kernel_irqchip = false;
> +    kvm_msi_via_irqfd_allowed = false;
> +    kvm_gsi_direct_mapping = false;
> +
> +    /* Clear the local list of presenter (hotplug) */
> +    kvm_cpu_disable_all();
> +}
> +
>  static void spapr_xive_kvm_realize(DeviceState *dev, Error **errp)
>  {
>      sPAPRXive *xive = SPAPR_XIVE_KVM(dev);
> diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> index eabc901a4556..a7e3ec32a761 100644
> --- a/hw/intc/xics_kvm.c
> +++ b/hw/intc/xics_kvm.c
> @@ -50,6 +50,16 @@ typedef struct KVMEnabledICP {
>  static QLIST_HEAD(, KVMEnabledICP)
>      kvm_enabled_icps = QLIST_HEAD_INITIALIZER(&kvm_enabled_icps);
>  
> +static void kvm_disable_icps(void)
> +{
> +    KVMEnabledICP *enabled_icp, *next;
> +
> +    QLIST_FOREACH_SAFE(enabled_icp, &kvm_enabled_icps, node, next) {
> +        QLIST_REMOVE(enabled_icp, node);
> +        g_free(enabled_icp);
> +    }
> +}
> +
>  /*
>   * ICP-KVM
>   */
> @@ -475,6 +485,53 @@ fail:
>      return -1;
>  }
>  
> +int xics_kvm_fini(sPAPRMachineState *spapr, Error **errp)
> +{
> +    int rc;
> +    struct kvm_create_device xics_create_device = {
> +        .fd = kernel_xics_fd,
> +        .type = KVM_DEV_TYPE_XICS,
> +        .flags = 0,
> +    };
> +
> +    /* The KVM XICS device is not in use */
> +    if (kernel_xics_fd == -1) {
> +        return 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 KVM XICS device");
> +        return -1;

Same comment as above.

> +    }
> +
> +    rc = kvm_vm_ioctl(kvm_state, KVM_DESTROY_DEVICE, &xics_create_device);
> +    if (rc < 0) {
> +        error_setg_errno(errp, -rc, "Error on KVM_DESTROY_DEVICE for XICS");
> +    }
> +    close(kernel_xics_fd);
> +    kernel_xics_fd = -1;
> +
> +    spapr_rtas_register(RTAS_IBM_SET_XIVE, NULL, 0);
> +    spapr_rtas_register(RTAS_IBM_GET_XIVE, NULL, 0);
> +    spapr_rtas_register(RTAS_IBM_INT_OFF, NULL, 0);
> +    spapr_rtas_register(RTAS_IBM_INT_ON, NULL, 0);
> +
> +    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");
> +
> +    kvm_kernel_irqchip = false;
> +    kvm_msi_via_irqfd_allowed = false;
> +    kvm_gsi_direct_mapping = false;
> +
> +    /* Clear the presenter from the VCPUs */
> +    kvm_disable_icps();
> +
> +    return rc;
> +}
> +
>  static void xics_kvm_register_types(void)
>  {
>      type_register_static(&ics_kvm_info);

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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