Re: [Qemu-devel] [PATCH v5 3/4] spapr_pci: enumerate and add PCI device tree

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 05/19/2015 06:26 PM, Nikunj A Dadhania wrote:
> All the PCI enumeration and device node creation was off-loaded to
> SLOF. With PCI hotplug support, code needed to be added to add device
> node. This creates multiple copy of the code one in SLOF and other in
> hotplug code. To unify this, the patch adds the pci device node
> creation in Qemu. For backward compatibility, a flag
> "qemu,phb-enumerated" is added to the phb, suggesting to SLOF to not
> do device node creation.
>
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> [ Squashed Michael's drc_index changes ]
> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> ---
>   hw/ppc/spapr_pci.c | 188 ++++++++++++++++++++++++++++++++++++++++++-----------
>   1 file changed, 150 insertions(+), 38 deletions(-)
>
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 8b02a3e..12f1b9c 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -23,6 +23,7 @@
>    * THE SOFTWARE.
>    */
>   #include "hw/hw.h"
> +#include "hw/sysbus.h"
>   #include "hw/pci/pci.h"
>   #include "hw/pci/msi.h"
>   #include "hw/pci/msix.h"
> @@ -35,6 +36,7 @@
>   #include "qemu/error-report.h"
>   #include "qapi/qmp/qerror.h"
>
> +#include "hw/pci/pci_bridge.h"
>   #include "hw/pci/pci_bus.h"
>   #include "hw/ppc/spapr_drc.h"
>   #include "sysemu/device_tree.h"
> @@ -742,6 +744,31 @@ static AddressSpace *spapr_pci_dma_iommu(PCIBus *bus, void *opaque, int devfn)
>       return &phb->iommu_as;
>   }
>
> +
> +static sPAPRDRConnector *spapr_phb_get_pci_drc(sPAPRPHBState *phb,
> +                                               PCIDevice *pdev)
> +{
> +    uint32_t busnr = pci_bus_num(PCI_BUS(qdev_get_parent_bus(DEVICE(pdev))));
> +    return spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_PCI,
> +                                    (phb->index << 16) |
> +                                    (busnr << 8) |
> +                                    pdev->devfn);
> +}
> +
> +static uint32_t spapr_phb_get_pci_drc_index(sPAPRPHBState *phb,
> +                                            PCIDevice *pdev)
> +{
> +    sPAPRDRConnector *drc = spapr_phb_get_pci_drc(phb, pdev);
> +    sPAPRDRConnectorClass *drck;
> +
> +    if (!drc) {
> +        return 0;
> +    }
> +
> +    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +    return drck->get_index(drc);
> +}
> +
>   /* Macros to operate with address in OF binding to PCI */
>   #define b_x(x, p, l)    (((x) & ((1<<(l))-1)) << (p))
>   #define b_n(x)          b_x((x), 31, 1) /* 0 if relocatable */
> @@ -879,12 +906,13 @@ static void populate_resource_props(PCIDevice *d, ResourceProps *rp)
>   }
>
>   static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
> -                                       int phb_index, int drc_index,
> +                                       sPAPRPHBState *sphb,
>                                          const char *drc_name)
>   {
>       ResourceProps rp;
>       bool is_bridge = false;
>       int pci_status;
> +    uint32_t drc_index = spapr_phb_get_pci_drc_index(sphb, dev);

Is this drc_index any different from the one which used to be passed to 
this function? If no, then I do not see the point in changing the prototype 
(or make another "this just makes code easier/nicer" patch). If yes, then 
it would be nice to see what the patch changed in this regard in the commit 
log.



>       if (pci_default_read_config(dev, PCI_HEADER_TYPE, 1) ==
>           PCI_HEADER_TYPE_BRIDGE) {
> @@ -945,8 +973,13 @@ static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
>        * processed by OF beforehand
>        */
>       _FDT(fdt_setprop_string(fdt, offset, "name", "pci"));
> -    _FDT(fdt_setprop(fdt, offset, "ibm,loc-code", drc_name, strlen(drc_name)));
> -    _FDT(fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index));
> +    if (drc_name) {
> +        _FDT(fdt_setprop(fdt, offset, "ibm,loc-code", drc_name,
> +                         strlen(drc_name)));
> +    }
> +    if (drc_index) {
> +        _FDT(fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index));
> +    }
>
>       _FDT(fdt_setprop_cell(fdt, offset, "#address-cells",
>                             RESOURCE_CELLS_ADDRESS));
> @@ -963,30 +996,34 @@ static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
>       return 0;
>   }
>
> +typedef struct sPAPRFDT {
> +    void *fdt;
> +    int node_off;
> +    sPAPRPHBState *sphb;
> +} sPAPRFDT;
> +
>   /* create OF node for pci device and required OF DT properties */
> -static void *spapr_create_pci_child_dt(sPAPRPHBState *phb, PCIDevice *dev,
> -                                       int drc_index, const char *drc_name,
> -                                       int *dt_offset)
> +static int spapr_create_pci_child_dt(PCIDevice *pdev, sPAPRFDT *p,
> +                                     const char *drc_name)

Why s/dev/pdev/?


>   {
> -    void *fdt;
> -    int offset, ret, fdt_size;
> -    int slot = PCI_SLOT(dev->devfn);
> -    int func = PCI_FUNC(dev->devfn);
> -    char nodename[512];
> +    int offset, ret;
> +    char nodename[64];

Why s/512/64/?

This change and the one above hide what the patch really does to 
spapr_create_pci_child_dt.


> +    int slot = PCI_SLOT(pdev->devfn);
> +    int func = PCI_FUNC(pdev->devfn);
>
> -    fdt = create_device_tree(&fdt_size);
>       if (func != 0) {
>           sprintf(nodename, "pci@%d,%d", slot, func);
>       } else {
>           sprintf(nodename, "pci@%d", slot);
>       }
> -    offset = fdt_add_subnode(fdt, 0, nodename);
> -    ret = spapr_populate_pci_child_dt(dev, fdt, offset, phb->index, drc_index,
> +    offset = fdt_add_subnode(p->fdt, p->node_off, nodename);
> +    ret = spapr_populate_pci_child_dt(pdev, p->fdt, offset, p->sphb,
>                                         drc_name);
>       g_assert(!ret);
> -
> -    *dt_offset = offset;
> -    return fdt;
> +    if (ret) {
> +        return 0;
> +    }
> +    return offset;
>   }
>
>   static void spapr_phb_add_pci_device(sPAPRDRConnector *drc,
> @@ -996,24 +1033,26 @@ static void spapr_phb_add_pci_device(sPAPRDRConnector *drc,
>   {
>       sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
>       DeviceState *dev = DEVICE(pdev);
> -    int drc_index = drck->get_index(drc);
>       const char *drc_name = drck->get_name(drc);
> -    void *fdt = NULL;
> -    int fdt_start_offset = 0;
> +    int fdt_start_offset = 0, fdt_size;
> +    sPAPRFDT s_fdt = {NULL, 0, NULL};
>
> -    /* boot-time devices get their device tree node created by SLOF, but for
> -     * hotplugged devices we need QEMU to generate it so the guest can fetch
> -     * it via RTAS
> -     */
>       if (dev->hotplugged) {


I understand the patch is not changing this but still while we are here -
spapr_phb_add_pci_device() is only called from spapr_phb_hot_plug_child(), 
how can dev->hotplugged be not true in this function (if it cannot, you 
could get rid of "out:"?



> -        fdt = spapr_create_pci_child_dt(phb, pdev, drc_index, drc_name,
> -                                        &fdt_start_offset);
> +        s_fdt.fdt = create_device_tree(&fdt_size);
> +        s_fdt.sphb = phb;
> +        s_fdt.node_off = 0;
> +        fdt_start_offset = spapr_create_pci_child_dt(pdev, &s_fdt, drc_name);
> +        if (!fdt_start_offset) {
> +            error_setg(errp, "Failed to create pci child device tree node");
> +            goto out;
> +        }
>       }
>
>       drck->attach(drc, DEVICE(pdev),
> -                 fdt, fdt_start_offset, !dev->hotplugged, errp);
> +                 s_fdt.fdt, fdt_start_offset, !dev->hotplugged, errp);
> +out:
>       if (*errp) {
> -        g_free(fdt);
> +        g_free(s_fdt.fdt);
>       }
>   }
>
> @@ -1043,16 +1082,6 @@ static void spapr_phb_remove_pci_device(sPAPRDRConnector *drc,
>       drck->detach(drc, DEVICE(pdev), spapr_phb_remove_pci_device_cb, phb, errp);
>   }
>
> -static sPAPRDRConnector *spapr_phb_get_pci_drc(sPAPRPHBState *phb,
> -                                               PCIDevice *pdev)

Just adding forward declaration would make the patch shorter.


> -{
> -    uint32_t busnr = pci_bus_num(PCI_BUS(qdev_get_parent_bus(DEVICE(pdev))));
> -    return spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_PCI,
> -                                    (phb->index << 16) |
> -                                    (busnr << 8) |
> -                                    pdev->devfn);
> -}
> -
>   static void spapr_phb_hot_plug_child(HotplugHandler *plug_handler,
>                                        DeviceState *plugged_dev, Error **errp)
>   {
> @@ -1482,6 +1511,75 @@ PCIHostState *spapr_create_phb(sPAPREnvironment *spapr, int index)
>       return PCI_HOST_BRIDGE(dev);
>   }
>
> +static void spapr_populate_pci_devices_dt(PCIBus *bus, PCIDevice *pdev,
> +                                          void *opaque)
> +{
> +    PCIBus *sec_bus;
> +    sPAPRFDT *p = opaque;
> +    int offset;
> +    sPAPRFDT s_fdt;
> +
> +    offset = spapr_create_pci_child_dt(pdev, p, NULL);
> +    if (!offset) {
> +        error_report("Failed to create pci child device tree node");
> +        return;
> +    }
> +
> +    if ((pci_default_read_config(pdev, PCI_HEADER_TYPE, 1) !=
> +         PCI_HEADER_TYPE_BRIDGE)) {
> +        return;
> +    }
> +
> +    sec_bus = pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));
> +    if (!sec_bus) {
> +        return;
> +    }
> +
> +    s_fdt.fdt = p->fdt;
> +    s_fdt.node_off = offset;
> +    s_fdt.sphb = p->sphb;
> +    pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
> +                        spapr_populate_pci_devices_dt,
> +                        &s_fdt);
> +}
> +
> +static void spapr_phb_pci_enumerate_bridge(PCIBus *bus, PCIDevice *pdev,
> +                                           void *opaque)
> +{
> +    unsigned int *bus_no = opaque;
> +    unsigned int primary = *bus_no;
> +    unsigned int secondary;
> +    unsigned int subordinate = 0xff;
> +
> +    if ((pci_default_read_config(pdev, PCI_HEADER_TYPE, 1) ==
> +         PCI_HEADER_TYPE_BRIDGE)) {


s/==/!=/ and "return" and no need in extra indent below.


> +        PCIBus *sec_bus = pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));
> +        secondary = *bus_no + 1;


(*bus_no)++;
secondary = *bus_no;

and remove "bus_no = *bus_no + 1" below?
In fact, I do not need much sense in having "secondary" variable in this 
function.

> +        pci_default_write_config(pdev, PCI_PRIMARY_BUS, primary, 1);
> +        pci_default_write_config(pdev, PCI_SECONDARY_BUS, secondary, 1);
> +        pci_default_write_config(pdev, PCI_SUBORDINATE_BUS, secondary, 1);
> +        *bus_no = *bus_no + 1;
> +        if (sec_bus) {

same here? Just like you did in spapr_populate_pci_devices_dt(). I do not 
insist though. But having less scopes just makes it easier/nicer to wrap 
long lines in QEMU coding style (new line starts under "(").


> +            pci_default_write_config(pdev, PCI_SUBORDINATE_BUS, subordinate, 1);
> +            pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
> +                                spapr_phb_pci_enumerate_bridge,
> +                                bus_no);
> +            pci_default_write_config(pdev, PCI_SUBORDINATE_BUS, *bus_no, 1);
> +        }
> +    }
> +}
> +
> +static void spapr_phb_pci_enumerate(sPAPRPHBState *phb)
> +{
> +    PCIBus *bus = PCI_HOST_BRIDGE(phb)->bus;
> +    unsigned int bus_no = 0;
> +
> +    pci_for_each_device(bus, pci_bus_num(bus),
> +                        spapr_phb_pci_enumerate_bridge,
> +                        &bus_no);
> +
> +}
> +
>   int spapr_populate_pci_dt(sPAPRPHBState *phb,
>                             uint32_t xics_phandle,
>                             void *fdt)
> @@ -1521,6 +1619,8 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
>           cpu_to_be32(b_ddddd(-1)|b_fff(0)), 0x0, 0x0, cpu_to_be32(-1)};
>       uint32_t interrupt_map[PCI_SLOT_MAX * PCI_NUM_PINS][7];
>       sPAPRTCETable *tcet;
> +    PCIBus *bus = PCI_HOST_BRIDGE(phb)->bus;
> +    sPAPRFDT s_fdt;
>
>       /* Start populating the FDT */
>       sprintf(nodename, "pci@%" PRIx64, phb->buid);
> @@ -1570,6 +1670,18 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
>                    tcet->liobn, tcet->bus_offset,
>                    tcet->nb_table << tcet->page_shift);
>
> +    /* Walk the bridges and program the bus numbers*/
> +    spapr_phb_pci_enumerate(phb);
> +    _FDT(fdt_setprop_cell(fdt, bus_off, "qemu,phb-enumerated", 0x1));


Can we also add a hack here to scan for the "qemu,phb-enumerated" string in 
the SLOF bin image?


> +
> +    /* Populate tree nodes with PCI devices attached */
> +    s_fdt.fdt = fdt;
> +    s_fdt.node_off = bus_off;
> +    s_fdt.sphb = phb;
> +    pci_for_each_device(bus, pci_bus_num(bus),
> +                        spapr_populate_pci_devices_dt,
> +                        &s_fdt);
> +
>       ret = spapr_drc_populate_dt(fdt, bus_off, OBJECT(phb),
>                                   SPAPR_DR_CONNECTOR_TYPE_PCI);
>       if (ret) {
>


-- 
Alexey