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From: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
In-Reply-To: <20150327032800.GA2900@voom.fritz.box>
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Date: Fri, 27 Mar 2015 10:04:27 +0530
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Subject: Re: [Qemu-devel] [PATCH 2/2] spapr: populate ibm,loc-code
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To: David Gibson <david@gibson.dropbear.id.au>
Cc: aik@ozlabs.ru, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, agraf@suse.de

David Gibson <david@gibson.dropbear.id.au> writes:

> 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(P=
owerPCCPU *cpu_,
>>      return H_SUCCESS;
>>  }
>>=20=20
>> +static target_ulong h_get_loc_code(PowerPCCPU *cpu, sPAPREnvironment *s=
papr,
>> +				   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.

I was thinking of new devices like SRIOV, etc, we land here and then
bifurcate accordingly.

>
>> +
>>  static spapr_hcall_fn papr_hypercall_table[(MAX_HCALL_OPCODE / 4) + 1];
>>  static spapr_hcall_fn kvmppc_hypercall_table[KVMPPC_HCALL_MAX - KVMPPC_=
HCALL_BASE + 1];
>>=20=20
>> @@ -1010,6 +1019,7 @@ static void hypercall_register_types(void)
>>=20=20
>>      /* ibm,client-architecture-support support */
>>      spapr_register_hypercall(KVMPPC_H_CAS, h_client_architecture_suppor=
t);
>> +    spapr_register_hypercall(KVMPPC_H_GET_LOC_CODE, h_get_loc_code);
>>  }
>>=20=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=20
>>  #include "hw/pci/pci_bus.h"
>> +#include "hw/vfio/vfio-common.h"
>>=20=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, hwadd=
r addr, bool msix,
>>      }
>>  }
>>=20=20
>> +bool spapr_h_get_loc_code(sPAPREnvironment *spapr, target_ulong config_=
addr, 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.

Ok

>
>> +{
>> +    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.

Sure, as per your previous comment, will update the return type and
return error/success codes directly.

>
>> +        }
>> +
>> +        /* 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.

Yes.

>
>> +        }
>> +    }
>> +
>> +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 *spap=
r,
>>                                  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(VFIOPCID=
evice *vdev)
>>      vdev->req_enabled =3D false;
>>  }
>>=20=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.

Alexey, has already answered that :-)

PCI enumeration happens in SLOF, keep on thinking of moving that to
qemu.

>
>> +#define KVMPPC_HCALL_MAX        KVMPPC_H_GET_LOC_CODE
>>=20=20
>>  extern sPAPREnvironment *spapr;
>>=20=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=20
>> +bool spapr_h_get_loc_code(sPAPREnvironment *spapr, target_ulong config_=
addr, target_ulong build,
>> +			  target_ulong loc_code, target_ulong size);
>> +
>>  #define TYPE_SPAPR_RTC "spapr-rtc"
>>=20=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=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