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Date: Fri, 27 Mar 2015 14:28:00 +1100
From: David Gibson <david@gibson.dropbear.id.au>
Message-ID: <20150327032800.GA2900@voom.fritz.box>
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Subject: Re: [Qemu-devel] [PATCH 2/2] spapr: populate ibm,loc-code
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To: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Cc: aik@ozlabs.ru, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, agraf@suse.de


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On Thu, Mar 26, 2015 at 12:12:12PM +0530, Nikunj A Dadhania wrote:
> Each hardware instance has a platform unique location code.  The OF
> device tree that describes a part of a hardware entity must include
> the =E2=80=9Cibm,loc-code=E2=80=9D property with a value that represents =
the location
> code for that hardware entity.
>=20
> Introduce an hcall to populate ibm,loc-cde.
> 1) PCI passthru devices need to identify with its own ibm,loc-code
>    available on the host.
> 2) Emulated devices encode as following: qemu_<name>:<slot>.<fn>
>=20
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr_hcall.c          | 10 +++++++++
>  hw/ppc/spapr_pci.c            | 49 +++++++++++++++++++++++++++++++++++++=
++++++
>  hw/vfio/pci.c                 | 18 ++++++++++++++++
>  include/hw/ppc/spapr.h        |  8 ++++++-
>  include/hw/vfio/vfio-common.h |  1 +
>  5 files changed, 85 insertions(+), 1 deletion(-)
>=20
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 4f76f1c..a577395 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -928,6 +928,15 @@ static target_ulong h_client_architecture_support(Po=
werPCCPU *cpu_,
>      return H_SUCCESS;
>  }
> =20
> +static target_ulong h_get_loc_code(PowerPCCPU *cpu, sPAPREnvironment *sp=
apr,
> +				   target_ulong opcode, target_ulong *args)
> +{
> +    if (!spapr_h_get_loc_code(spapr, args[0], args[1], args[2], args[3])=
) {
> +        return H_PARAMETER;
> +    }
> +    return H_SUCCESS;
> +}

There's no point to this wrapper.  The hypercalls are defined by PAPR,
so making an "spapr" version of the hypercall function is redundant.

> +
>  static spapr_hcall_fn papr_hypercall_table[(MAX_HCALL_OPCODE / 4) + 1];
>  static spapr_hcall_fn kvmppc_hypercall_table[KVMPPC_HCALL_MAX - KVMPPC_H=
CALL_BASE + 1];
> =20
> @@ -1010,6 +1019,7 @@ static void hypercall_register_types(void)
> =20
>      /* ibm,client-architecture-support support */
>      spapr_register_hypercall(KVMPPC_H_CAS, h_client_architecture_support=
);
> +    spapr_register_hypercall(KVMPPC_H_GET_LOC_CODE, h_get_loc_code);
>  }
> =20
>  type_init(hypercall_register_types)
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 05f4fac..65cdb91 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -35,6 +35,7 @@
>  #include "qemu/error-report.h"
> =20
>  #include "hw/pci/pci_bus.h"
> +#include "hw/vfio/vfio-common.h"
> =20
>  /* Copied from the kernel arch/powerpc/platforms/pseries/msi.c */
>  #define RTAS_QUERY_FN           0
> @@ -248,6 +249,54 @@ static void spapr_msi_setmsg(PCIDevice *pdev, hwaddr=
 addr, bool msix,
>      }
>  }
> =20
> +bool spapr_h_get_loc_code(sPAPREnvironment *spapr, target_ulong config_a=
ddr, target_ulong buid,
> +                          target_ulong loc_code, target_ulong size)

bool as a success/failure indication isn't a normal interface.  Just
get rid of the wrapper and return H_ERROR codes directly.

> +{
> +    sPAPRPHBState *sphb =3D NULL;
> +    PCIDevice *pdev =3D NULL;
> +    char *buf, path[PATH_MAX];
> +    struct stat st;
> +
> +    sphb =3D find_phb(spapr, buid);
> +    if (sphb) {
> +        pdev =3D find_dev(spapr, buid, config_addr);
> +    }
> +
> +    if (!sphb || !pdev) {
> +        error_report("spapr_h_get_loc_code: Device not found");
> +        return false;
> +    }
> +
> +    /* For a VFIO device, get the location in the device tree */
> +    if (pdev->is_vfio && vfio_get_devspec(pdev, &buf)) {
> +        snprintf(path, sizeof(path), "/proc/device-tree%s/ibm,loc-code",=
 buf);
> +        g_free(buf);
> +        if (stat(path, &st) < 0) {
> +            goto fail;

This isn't really an acceptable use of goto.  And the label is badly
named, because it doesn't fail, just fall back to an alternate method.

> +        }
> +
> +        /* A valid file, now read the loc-code */
> +        if (g_file_get_contents(path, &buf, NULL, NULL)) {
> +            cpu_physical_memory_write(loc_code, buf, strlen(buf));
> +            g_free(buf);
> +            goto out;

This could just be a return.

> +        }
> +    }
> +
> +fail:
> +    /*
> +     * For non-vfio devices and failure cases, make up the location
> +     * code out of the name, slot and function.
> +     *
> +     *       qemu_<name>:<slot>.<fn>
> +     */
> +    snprintf(path, sizeof(path), "qemu_%s:%02d.%1d", pdev->name,
> +             PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
> +    cpu_physical_memory_write(loc_code, path, size);
> + out:
> +    return true;
> +}
> +
>  static void rtas_ibm_change_msi(PowerPCCPU *cpu, sPAPREnvironment *spapr,
>                                  uint32_t token, uint32_t nargs,
>                                  target_ulong args, uint32_t nret,
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 95d666e..dd97258 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3319,6 +3319,24 @@ static void vfio_unregister_req_notifier(VFIOPCIDe=
vice *vdev)
>      vdev->req_enabled =3D false;
>  }
> =20
> +bool vfio_get_devspec(PCIDevice *pdev, char **value)
> +{
> +    VFIOPCIDevice *vdev =3D DO_UPCAST(VFIOPCIDevice, pdev, pdev);
> +    char path[PATH_MAX];
> +    struct stat st;
> +
> +    snprintf(path, sizeof(path),
> +             "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/devspec",
> +             vdev->host.domain, vdev->host.bus, vdev->host.slot,
> +             vdev->host.function);
> +
> +    if (stat(path, &st) < 0) {
> +        return false;
> +    }
> +
> +    return g_file_get_contents(path, value, NULL, NULL);
> +}
> +
>  static int vfio_initfn(PCIDevice *pdev)
>  {
>      VFIOPCIDevice *vdev =3D DO_UPCAST(VFIOPCIDevice, pdev, pdev);
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index af71e8b..d3fad67 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -310,7 +310,10 @@ typedef struct sPAPREnvironment {
>  #define KVMPPC_H_LOGICAL_MEMOP  (KVMPPC_HCALL_BASE + 0x1)
>  /* Client Architecture support */
>  #define KVMPPC_H_CAS            (KVMPPC_HCALL_BASE + 0x2)
> -#define KVMPPC_HCALL_MAX        KVMPPC_H_CAS
> +#define KVMPPC_H_RTAS_UPDATE    (KVMPPC_HCALL_BASE + 0x3)
> +#define KVMPPC_H_REPORT_MC_ERR  (KVMPPC_HCALL_BASE + 0x4)
> +#define KVMPPC_H_GET_LOC_CODE   (KVMPPC_HCALL_BASE + 0x5)

Come to that, I don't even understand why you're defining a new hcall.
Why not just put the loc-code in the initial device tree with the
other information.

> +#define KVMPPC_HCALL_MAX        KVMPPC_H_GET_LOC_CODE
> =20
>  extern sPAPREnvironment *spapr;
> =20
> @@ -522,6 +525,9 @@ int spapr_tcet_dma_dt(void *fdt, int node_off, const =
char *propname,
>                        sPAPRTCETable *tcet);
>  void spapr_pci_switch_vga(bool big_endian);
> =20
> +bool spapr_h_get_loc_code(sPAPREnvironment *spapr, target_ulong config_a=
ddr, target_ulong build,
> +			  target_ulong loc_code, target_ulong size);
> +
>  #define TYPE_SPAPR_RTC "spapr-rtc"
> =20
>  void spapr_rtc_read(DeviceState *dev, struct tm *tm, uint32_t *ns);
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 0d1fb80..6dffa8c 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -140,6 +140,7 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace *=
as);
>  void vfio_put_group(VFIOGroup *group);
>  int vfio_get_device(VFIOGroup *group, const char *name,
>                      VFIODevice *vbasedev);
> +bool vfio_get_devspec(PCIDevice *pdev, char **value);
> =20
>  extern const MemoryRegionOps vfio_region_ops;
>  extern QLIST_HEAD(vfio_group_head, VFIOGroup) vfio_group_list;

--=20
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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