On Mon, Dec 16, 2019 at 03:19:22PM +1100, Alexey Kardashevskiy wrote:
> By default a pseries guest supports a H_PUT_TCE hypercall which maps
> a single IOMMU page in a DMA window. Additionally the hypervisor may
> support H_PUT_TCE_INDIRECT/H_STUFF_TCE which update multiple TCEs at once;
> this is advertised via the device tree /rtas/ibm,hypertas-functions
> property which Linux converts to FW_FEATURE_MULTITCE.
>
> FW_FEATURE_MULTITCE is checked when dma_iommu_ops is used; however
> the code managing the huge DMA window (DDW) ignores it and calls
> H_PUT_TCE_INDIRECT even if it is explicitly disabled via
> the "multitce=off" kernel command line parameter.
>
> This adds FW_FEATURE_MULTITCE checking to the DDW code path.
>
> This changes tce_build_pSeriesLP to take liobn and page size as
> the huge window does not have iommu_table descriptor which usually
> the place to store these numbers.
>
> Fixes: 4e8b0cf46b25 ("powerpc/pseries: Add support for dynamic dma windows")
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> ---
>
> I've put "Fixes" which is from 2011-02-10 but probably should remove it,
> or otherwise all these "stable backport branch" scripts will react on
> "Fixes" and try pulling this back and we do not really want this as
> this patch won't help anyone with anything useful.
>
> ---
> Changes:
> v2
> * added "fixes"
> ---
> arch/powerpc/platforms/pseries/iommu.c | 44 ++++++++++++++++++--------
> 1 file changed, 30 insertions(+), 14 deletions(-)
some minor comments below.
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index df7db33ca93b..f6e9b87c82fc 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -132,10 +132,10 @@ static unsigned long tce_get_pseries(struct iommu_table *tbl, long index)
> return be64_to_cpu(*tcep);
> }
>
> -static void tce_free_pSeriesLP(struct iommu_table*, long, long);
> +static void tce_free_pSeriesLP(unsigned long liobn, long, long);
> static void tce_freemulti_pSeriesLP(struct iommu_table*, long, long);
>
> -static int tce_build_pSeriesLP(struct iommu_table *tbl, long tcenum,
> +static int tce_build_pSeriesLP(unsigned long liobn, long tcenum, long tceshift,
> long npages, unsigned long uaddr,
> enum dma_data_direction direction,
> unsigned long attrs)
> @@ -146,25 +146,25 @@ static int tce_build_pSeriesLP(struct iommu_table *tbl, long tcenum,
> int ret = 0;
> long tcenum_start = tcenum, npages_start = npages;
>
> - rpn = __pa(uaddr) >> TCE_SHIFT;
> + rpn = __pa(uaddr) >> tceshift;
> proto_tce = TCE_PCI_READ;
> if (direction != DMA_TO_DEVICE)
> proto_tce |= TCE_PCI_WRITE;
>
> while (npages--) {
> - tce = proto_tce | (rpn & TCE_RPN_MASK) << TCE_RPN_SHIFT;
> - rc = plpar_tce_put((u64)tbl->it_index, (u64)tcenum << 12, tce);
> + tce = proto_tce | (rpn & TCE_RPN_MASK) << tceshift;
> + rc = plpar_tce_put((u64)liobn, (u64)tcenum << tceshift, tce);
>
> if (unlikely(rc == H_NOT_ENOUGH_RESOURCES)) {
> ret = (int)rc;
> - tce_free_pSeriesLP(tbl, tcenum_start,
> + tce_free_pSeriesLP(liobn, tcenum_start,
> (npages_start - (npages + 1)));
> break;
> }
>
> if (rc && printk_ratelimit()) {
> printk("tce_build_pSeriesLP: plpar_tce_put failed. rc=%lld\n", rc);
> - printk("\tindex = 0x%llx\n", (u64)tbl->it_index);
> + printk("\tindex = 0x%llx\n", (u64)liobn);
> printk("\ttcenum = 0x%llx\n", (u64)tcenum);
> printk("\ttce val = 0x%llx\n", tce );
> dump_stack();
> @@ -193,7 +193,8 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
> unsigned long flags;
>
> if ((npages == 1) || !firmware_has_feature(FW_FEATURE_MULTITCE)) {
> - return tce_build_pSeriesLP(tbl, tcenum, npages, uaddr,
> + return tce_build_pSeriesLP(tbl->it_index, tcenum,
> + tbl->it_page_shift, npages, uaddr,
> direction, attrs);
> }
>
> @@ -209,8 +210,9 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
> /* If allocation fails, fall back to the loop implementation */
> if (!tcep) {
> local_irq_restore(flags);
> - return tce_build_pSeriesLP(tbl, tcenum, npages, uaddr,
> - direction, attrs);
> + return tce_build_pSeriesLP(tbl->it_index, tcenum,
> + tbl->it_page_shift,
> + npages, uaddr, direction, attrs);
> }
> __this_cpu_write(tce_page, tcep);
> }
> @@ -261,16 +263,16 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
> return ret;
> }
>
> -static void tce_free_pSeriesLP(struct iommu_table *tbl, long tcenum, long npages)
> +static void tce_free_pSeriesLP(unsigned long liobn, long tcenum, long npages)
> {
> u64 rc;
>
> while (npages--) {
> - rc = plpar_tce_put((u64)tbl->it_index, (u64)tcenum << 12, 0);
> + rc = plpar_tce_put((u64)liobn, (u64)tcenum << 12, 0);
minor nitpick. The magic number '12' can be replaced by TCE_SHIFT
>
> if (rc && printk_ratelimit()) {
> printk("tce_free_pSeriesLP: plpar_tce_put failed. rc=%lld\n", rc);
> - printk("\tindex = 0x%llx\n", (u64)tbl->it_index);
> + printk("\tindex = 0x%llx\n", (u64)liobn);
> printk("\ttcenum = 0x%llx\n", (u64)tcenum);
> dump_stack();
> }
> @@ -285,7 +287,7 @@ static void tce_freemulti_pSeriesLP(struct iommu_table *tbl, long tcenum, long n
> u64 rc;
>
> if (!firmware_has_feature(FW_FEATURE_MULTITCE))
> - return tce_free_pSeriesLP(tbl, tcenum, npages);
> + return tce_free_pSeriesLP(tbl->it_index, tcenum, npages);
>
> rc = plpar_tce_stuff((u64)tbl->it_index, (u64)tcenum << 12, 0, npages);
Same here.
>
> @@ -400,6 +402,20 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
> u64 rc = 0;
> long l, limit;
>
> + if (!firmware_has_feature(FW_FEATURE_MULTITCE)) {
> + unsigned long tceshift = be32_to_cpu(maprange->tce_shift);
> + unsigned long dmastart = (start_pfn << PAGE_SHIFT) +
> + be64_to_cpu(maprange->dma_base);
> + unsigned long tcenum = dmastart >> tceshift;
> + unsigned long npages = num_pfn << PAGE_SHIFT >>
> + be32_to_cpu(maprange->tce_shift);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
this can be 'tceshift'. Saves some cpu-cycles.
> + void *uaddr = __va(start_pfn << PAGE_SHIFT);
> +
> + return tce_build_pSeriesLP(be32_to_cpu(maprange->liobn),
> + tcenum, tceshift, npages, (unsigned long) uaddr,
> + DMA_BIDIRECTIONAL, 0);
> + }
> +
The code under the if statement, go into a static inline function of its own?
> local_irq_disable(); /* to protect tcep and the page behind it */
> tcep = __this_cpu_read(tce_page);
>
Reviewed-by: Ram Pai <linuxram@xxxxxxxxxx>
--
Ram Pai
