Re: [PATCH v6 11/42] powerpc/powernv: Trace DMA32 segments consumed by PE

Alexey Kardashevskiy
2015-08-10T09:43:48Z

On 08/06/2015 02:11 PM, Gavin Shan wrote:
> On P7IOC, the whole DMA32 space is divided evenly to 256MB segments.
> Each PE can consume one or multiple DMA32 segments. Current code
> doesn't trace the available DMA32 segments and those consumed by
> one particular PE. It's conflicting with PCI hotplug.
>
> The patch introduces one bitmap to PHB to trace the available
> DMA32 segments for allocation, more fields to "struct pnv_ioda_pe"
> to trace the consumed DMA32 segments by the PE, which is going to
> be released when the PE is destroyed at PCI unplugging time.
>
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/powernv/pci-ioda.c | 40 +++++++++++++++++++++++--------
> arch/powerpc/platforms/powernv/pci.h | 4 +++-
> 2 files changed, 33 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index cd22002..57ba8fd 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -1946,6 +1946,7 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
>
> /* Grab a 32-bit TCE table */
> pe->dma32_seg = base;
> + pe->dma32_segcount = segs;
> pe_info(pe, " Setting up 32-bit TCE table at %08x..%08x\n",
> (base << 28), ((base + segs) << 28) - 1);
>
> @@ -2006,8 +2007,13 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
> return;
> fail:
> /* XXX Failure: Try to fallback to 64-bit only ? */
> - if (pe->dma32_seg >= 0)
> + if (pe->dma32_seg >= 0) {
> + bitmap_clear(phb->ioda.dma32_segmap,
> + pe->dma32_seg, pe->dma32_segcount);
> pe->dma32_seg = -1;
> + pe->dma32_segcount = 0;
> + }
> +
> if (tce_mem)
> __free_pages(tce_mem, get_order(TCE32_TABLE_SIZE * segs));
> if (tbl) {
> @@ -2443,12 +2449,11 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
> pnv_ioda_setup_bus_dma(pe, pe->pbus);
> }
>
> -static unsigned int pnv_ioda1_setup_dma(struct pnv_phb *phb,
> - struct pnv_ioda_pe *pe,
> - unsigned int base)
> +static void pnv_ioda1_setup_dma(struct pnv_phb *phb,
> + struct pnv_ioda_pe *pe)
> {
> struct pci_controller *hose = phb->hose;
> - unsigned int dma_weight, segs;
> + unsigned int dma_weight, base, segs;
>
> /* Calculate the PHB's DMA weight */
> dma_weight = pnv_ioda_phb_dma_weight(phb);
> @@ -2461,11 +2466,28 @@ static unsigned int pnv_ioda1_setup_dma(struct pnv_phb *phb,
> else
> segs = (pe->dma32_weight *
> phb->ioda.dma32_segcount) / dma_weight;
> +
> + /*
> + * Allocate DMA32 segments. We might not have enough
> + * resources available. However we expect at least one
> + * to be available.
> + */
> + do {
> + base = bitmap_find_next_zero_area(phb->ioda.dma32_segmap,
> + phb->ioda.dma32_segcount,
> + 0, segs, 0);
> + if (base < phb->ioda.dma32_segcount) {
> + bitmap_set(phb->ioda.dma32_segmap, base, segs);
> + break;
> + }
> + } while (--segs);

If segs==0 before entering the loop, the loop will execute 0xfffffffe
times. Make it for(;segs;--segs){ }.

> +
> + if (WARN_ON(!segs))
> + return;
> +
> pe_info(pe, "DMA weight %d, assigned %d segments\n",
> pe->dma32_weight, segs);
> pnv_pci_ioda_setup_dma_pe(phb, pe, base, segs);
> -
> - return segs;
> }
>
> #ifdef CONFIG_PCI_MSI
> @@ -2933,20 +2955,18 @@ static void pnv_pci_ioda_setup_DMA(void)
> struct pci_controller *hose, *tmp;
> struct pnv_phb *phb;
> struct pnv_ioda_pe *pe;
> - unsigned int base;
>
> list_for_each_entry_safe(hose, tmp, &hose_list, list_node) {
> phb = hose->private_data;
> pnv_pci_ioda_setup_opal_tce_kill(phb);
>
> - base = 0;
> list_for_each_entry(pe, &phb->ioda.pe_dma_list, dma_link) {
> if (!pe->dma32_weight)
> continue;
>
> switch (phb->type) {
> case PNV_PHB_IODA1:
> - base += pnv_ioda1_setup_dma(phb, pe, base);
> + pnv_ioda1_setup_dma(phb, pe);
> break;
> case PNV_PHB_IODA2:
> pnv_pci_ioda2_setup_dma_pe(phb, pe);
> diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
> index 574fe43..1dc9578 100644
> --- a/arch/powerpc/platforms/powernv/pci.h
> +++ b/arch/powerpc/platforms/powernv/pci.h
> @@ -65,6 +65,7 @@ struct pnv_ioda_pe {
>
> /* "Base" iommu table, ie, 4K TCEs, 32-bit DMA */
> int dma32_seg;
> + int dma32_segcount;
> struct iommu_table_group table_group;
>
> /* 64-bit TCE bypass region */
> @@ -153,10 +154,11 @@ struct pnv_phb {
> unsigned int io_segsize;
> unsigned int io_pci_base;
>
> - /* IO, M32, M64 segment maps */
> + /* IO, M32, M64, DMA32 segment maps */
> unsigned long io_segmap[8];
> unsigned long m32_segmap[8];
> unsigned long m64_segmap[8];
> + unsigned long dma32_segmap[8];
>
> /* PE allocation */
> struct mutex pe_alloc_mutex;
>

--
Alexey