Re: [PATCH kernel v9 20/32] powerpc/powernv/ioda2: Introduce pnv_pci_create_table/pnv_pci_free_table

Alexey Kardashevskiy
2015-05-01T10:13:15Z

On 04/29/2015 02:39 PM, David Gibson wrote:
> On Sat, Apr 25, 2015 at 10:14:44PM +1000, Alexey Kardashevskiy wrote:
>> This is a part of moving TCE table allocation into an iommu_ops
>> callback to support multiple IOMMU groups per one VFIO container.
>>
>> This moves a table creation window to the file with common powernv-pci
>> helpers as it does not do anything IODA2-specific.
>>
>> This adds pnv_pci_free_table() helper to release the actual TCE table.
>>
>> This enforces window size to be a power of two.
>>
>> This should cause no behavioural change.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
>> ---
>> Changes:
>> v9:
>> * moved helpers to the common powernv pci.c file from pci-ioda.c
>> * moved bits from pnv_pci_create_table() to pnv_alloc_tce_table_pages()
>> ---
>> arch/powerpc/platforms/powernv/pci-ioda.c | 36 ++++++------------
>> arch/powerpc/platforms/powernv/pci.c | 61 +++++++++++++++++++++++++++++++
>> arch/powerpc/platforms/powernv/pci.h | 4 ++
>> 3 files changed, 76 insertions(+), 25 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>> index a80be34..b9b3773 100644
>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>> @@ -1307,8 +1307,7 @@ static void pnv_pci_ioda2_release_dma_pe(struct pci_dev *dev, struct pnv_ioda_pe
>> if (rc)
>> pe_warn(pe, "OPAL error %ld release DMA window\n", rc);
>>
>> - iommu_reset_table(tbl, of_node_full_name(dev->dev.of_node));
>> - free_pages(addr, get_order(TCE32_TABLE_SIZE));
>> + pnv_pci_free_table(tbl);
>> }
>>
>> static void pnv_ioda_release_vf_PE(struct pci_dev *pdev, u16 num_vfs)
>> @@ -2039,10 +2038,7 @@ static struct iommu_table_group_ops pnv_pci_ioda2_ops = {
>> static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>> struct pnv_ioda_pe *pe)
>> {
>> - struct page *tce_mem = NULL;
>> - void *addr;
>> struct iommu_table *tbl = &pe->table_group.tables[0];
>> - unsigned int tce_table_size, end;
>> int64_t rc;
>>
>> /* We shouldn't already have a 32-bit DMA associated */
>> @@ -2053,29 +2049,20 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>>
>> /* The PE will reserve all possible 32-bits space */
>> pe->tce32_seg = 0;
>> - end = (1 << ilog2(phb->ioda.m32_pci_base));
>> - tce_table_size = (end / 0x1000) * 8;
>> pe_info(pe, "Setting up 32-bit TCE table at 0..%08x\n",
>> - end);
>> + phb->ioda.m32_pci_base);
>>
>> - /* Allocate TCE table */
>> - tce_mem = alloc_pages_node(phb->hose->node, GFP_KERNEL,
>> - get_order(tce_table_size));
>> - if (!tce_mem) {
>> - pe_err(pe, "Failed to allocate a 32-bit TCE memory\n");
>> - goto fail;
>> + rc = pnv_pci_create_table(&pe->table_group, pe->phb->hose->node,
>> + 0, IOMMU_PAGE_SHIFT_4K, phb->ioda.m32_pci_base, tbl);
>> + if (rc) {
>> + pe_err(pe, "Failed to create 32-bit TCE table, err %ld", rc);
>> + return;
>> }
>> - addr = page_address(tce_mem);
>> - memset(addr, 0, tce_table_size);
>> -
>> - /* Setup iommu */
>> - tbl->it_table_group = &pe->table_group;
>> -
>> - /* Setup linux iommu table */
>> - pnv_pci_setup_iommu_table(tbl, addr, tce_table_size, 0,
>> - IOMMU_PAGE_SHIFT_4K);
>>
>> tbl->it_ops = &pnv_ioda2_iommu_ops;
>> +
>> + /* Setup iommu */
>> + tbl->it_table_group = &pe->table_group;
>> iommu_init_table(tbl, phb->hose->node);
>> #ifdef CONFIG_IOMMU_API
>> pe->table_group.ops = &pnv_pci_ioda2_ops;
>> @@ -2121,8 +2108,7 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>> fail:
>> if (pe->tce32_seg >= 0)
>> pe->tce32_seg = -1;
>> - if (tce_mem)
>> - __free_pages(tce_mem, get_order(tce_table_size));
>> + pnv_pci_free_table(tbl);
>> }
>>
>> static void pnv_ioda_setup_dma(struct pnv_phb *phb)
>> diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
>> index e8802ac..6bcfad5 100644
>> --- a/arch/powerpc/platforms/powernv/pci.c
>> +++ b/arch/powerpc/platforms/powernv/pci.c
>> @@ -20,7 +20,9 @@
>> #include <linux/io.h>
>> #include <linux/msi.h>
>> #include <linux/iommu.h>
>> +#include <linux/memblock.h>
>>
>> +#include <asm/mmzone.h>
>> #include <asm/sections.h>
>> #include <asm/io.h>
>> #include <asm/prom.h>
>> @@ -645,6 +647,65 @@ void pnv_pci_setup_iommu_table(struct iommu_table *tbl,
>> tbl->it_type = TCE_PCI;
>> }
>>
>> +static __be64 *pnv_alloc_tce_table_pages(int nid, unsigned shift,
>> + unsigned long *tce_table_allocated)
>
> I'm a bit confused by the tce_table_allocated parameter. What's the
> circumstance where more memory is requested than required, and why
> does it matter to the caller?
>
>> +{
>> + struct page *tce_mem = NULL;
>> + __be64 *addr;
>> + unsigned order = max_t(unsigned, shift, PAGE_SHIFT) - PAGE_SHIFT;
>> + unsigned long local_allocated = 1UL << (order + PAGE_SHIFT);
>> +
>> + tce_mem = alloc_pages_node(nid, GFP_KERNEL, order);
>> + if (!tce_mem) {
>> + pr_err("Failed to allocate a TCE memory, order=%d\n", order);
>> + return NULL;
>> + }
>> + addr = page_address(tce_mem);
>> + memset(addr, 0, local_allocated);
>> + *tce_table_allocated = local_allocated;
>> +
>> + return addr;
>> +}
>> +
>> +long pnv_pci_create_table(struct iommu_table_group *table_group, int nid,
>> + __u64 bus_offset, __u32 page_shift, __u64 window_size,
>> + struct iommu_table *tbl)
>
> The table_group parameter is redundant, isn't it? It must be equal to
> tbl->table_group, yes?
>
> Or would it make more sense for this function to set
> tbl->table_group?

I removed table_group from here.

> And for that matter wouldn't it make more sense for
> this to set it_size as well?

Missed this comment. It does set it_size by calling
pnv_pci_setup_iommu_table().

>> +{
>> + void *addr;
>> + unsigned long tce_table_allocated = 0;
>> + const unsigned window_shift = ilog2(window_size);
>> + unsigned entries_shift = window_shift - page_shift;
>> + unsigned table_shift = entries_shift + 3;
>> + const unsigned long tce_table_size = max(0x1000UL, 1UL << table_shift);
>
> So, here you round up to 4k, the in the alloc function you round up to
> PAGE_SIZE (which may or may not be the same). It's not clear to me why
> there are two rounds of rounding up.

@tce_table_size will be programmed later into IODA2 via OPAL and OPAL will
reject a window if it is less than 4K. I'll rework the whole thing just to
align it to PAGE_SIZE as this is what it really is anyway.

--
Alexey