Re: [Qemu-devel] [PULL 32/33] xics_kvm: use KVM helpers

[Greg Kurz]

On Tue, 12 Jun 2018 16:45:02 +1000
David Gibson <address@hidden> wrote:

> From: Cédric Le Goater <address@hidden>
> 
> The KVM helpers hide the low level interface used to communicate to
> the XICS KVM device and provide a good cleanup to the XICS KVM models.
> 
> Signed-off-by: Cédric Le Goater <address@hidden>
> Signed-off-by: David Gibson <address@hidden>
> ---
>  hw/intc/xics_kvm.c | 52 +++++++++++++---------------------------------
>  1 file changed, 14 insertions(+), 38 deletions(-)
> 
> diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> index 89fb20e2c5..8bdf6afe82 100644
> --- a/hw/intc/xics_kvm.c
> +++ b/hw/intc/xics_kvm.c
> @@ -56,10 +56,6 @@ static QLIST_HEAD(, KVMEnabledICP)
>  static void icp_get_kvm_state(ICPState *icp)
>  {
>      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 */
> @@ -67,7 +63,7 @@ static void icp_get_kvm_state(ICPState *icp)
>          return;
>      }
>  
> -    ret = kvm_vcpu_ioctl(icp->cs, KVM_GET_ONE_REG, &reg);
> +    ret = kvm_get_one_reg(icp->cs, KVM_REG_PPC_ICP_STATE, &state);
>      if (ret != 0) {
>          error_report("Unable to retrieve KVM interrupt controller state"
>                  " for CPU %ld: %s", kvm_arch_vcpu_id(icp->cs), 
> strerror(errno));
> @@ -96,10 +92,6 @@ static void icp_synchronize_state(ICPState *icp)
>  static int icp_set_kvm_state(ICPState *icp, 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 */
> @@ -111,7 +103,7 @@ static int icp_set_kvm_state(ICPState *icp, int 
> version_id)
>          | ((uint64_t)icp->mfrr << KVM_REG_PPC_ICP_MFRR_SHIFT)
>          | ((uint64_t)icp->pending_priority << KVM_REG_PPC_ICP_PPRI_SHIFT);
>  
> -    ret = kvm_vcpu_ioctl(icp->cs, KVM_SET_ONE_REG, &reg);
> +    ret = kvm_set_one_reg(icp->cs, KVM_REG_PPC_ICP_STATE, &state);
>      if (ret != 0) {
>          error_report("Unable to restore KVM interrupt controller state (0x%"
>                  PRIx64 ") for CPU %ld: %s", state, kvm_arch_vcpu_id(icp->cs),
> @@ -185,21 +177,15 @@ static const TypeInfo icp_kvm_info = {
>  static void ics_get_kvm_state(ICSState *ics)
>  {
>      uint64_t state;
> -    struct kvm_device_attr attr = {
> -        .flags = 0,
> -        .group = KVM_DEV_XICS_GRP_SOURCES,
> -        .addr = (uint64_t)(uintptr_t)&state,
> -    };
>      int i;
> +    Error *local_err = NULL;
>  
>      for (i = 0; i < ics->nr_irqs; i++) {
>          ICSIRQState *irq = &ics->irqs[i];
> -        int ret;
> -
> -        attr.attr = i + ics->offset;
>  
> -        ret = ioctl(kernel_xics_fd, KVM_GET_DEVICE_ATTR, &attr);
> -        if (ret != 0) {
> +        kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
> +                          i + ics->offset, &state, false, &local_err);
> +        if (local_err) {
>              error_report("Unable to retrieve KVM interrupt controller state"
>                      " for IRQ %d: %s", i + ics->offset, strerror(errno));
>              exit(1);
> @@ -255,19 +241,13 @@ static void ics_synchronize_state(ICSState *ics)
>  static int ics_set_kvm_state(ICSState *ics, int version_id)
>  {
>      uint64_t state;
> -    struct kvm_device_attr attr = {
> -        .flags = 0,
> -        .group = KVM_DEV_XICS_GRP_SOURCES,
> -        .addr = (uint64_t)(uintptr_t)&state,
> -    };
>      int i;
> +    Error *local_err = NULL;
>  
>      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;
> @@ -293,8 +273,9 @@ static int ics_set_kvm_state(ICSState *ics, int 
> version_id)
>                  state |= KVM_XICS_QUEUED;
>          }
>  
> -        ret = ioctl(kernel_xics_fd, KVM_SET_DEVICE_ATTR, &attr);
> -        if (ret != 0) {
> +        kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
> +                          i + ics->offset, &state, true, &local_err);
> +        if (local_err) {
>              error_report("Unable to restore KVM interrupt controller state"
>                      " for IRQs %d: %s", i + ics->offset, strerror(errno));
>              return ret;

This breaks build on CentOS 7.5 with gcc-4.8.5-28.el7_5.1.ppc64le:

hw/intc/xics_kvm.c: In function ‘ics_set_kvm_state’:
hw/intc/xics_kvm.c:281:13: error: ‘ret’ may be used uninitialized in this
 function [-Werror=maybe-uninitialized]
             return ret;

Also, if kvm_device_access() has set local_err, then it should be used or
freed. I think that what you need to do here is something like:


        ret = kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
                                i + ics->offset, &state, true, &local_err);
        if (local_err) {
            error_reportf_err(local_err, "Unable to restore KVM interrupt"
                              " controller state for IRQs %d: ",
                              i + ics->offset);
            return ret;
        }

This also happens to fix the return value of ics_set_kvm_state()
which is propagated as is to VMState, and thus should be a negative
errno.

> @@ -391,10 +372,6 @@ static void rtas_dummy(PowerPCCPU *cpu, 
> sPAPRMachineState *spapr,
>  int xics_kvm_init(sPAPRMachineState *spapr, Error **errp)
>  {
>      int rc;
> -    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,
> @@ -431,20 +408,19 @@ int xics_kvm_init(sPAPRMachineState *spapr, Error 
> **errp)
>          goto fail;
>      }
>  
> -    /* Create the kernel ICP */
> -    rc = kvm_vm_ioctl(kvm_state, KVM_CREATE_DEVICE, &xics_create_device);
> +    /* Create the KVM XICS device */
> +    rc = kvm_create_device(kvm_state, KVM_DEV_TYPE_XICS, false);
>      if (rc < 0) {
>          error_setg_errno(errp, -rc, "Error on KVM_CREATE_DEVICE for XICS");
>          goto fail;
>      }
>  
> -    kernel_xics_fd = xics_create_device.fd;
> -
> +    kernel_xics_fd = rc;
>      kvm_kernel_irqchip = true;
>      kvm_msi_via_irqfd_allowed = true;
>      kvm_gsi_direct_mapping = true;
>  
> -    return rc;
> +    return 0;
>  
>  fail:
>      kvmppc_define_rtas_kernel_token(0, "ibm,set-xive");