Re: [PATCH kernel v10 20/34] powerpc/powernv/ioda2: Move TCE kill register address to PE

From: Alexey Kardashevskiy
Date: Wed May 13 2015 - 23:39:57 EST

On 05/14/2015 12:10 PM, Gavin Shan wrote:
On Tue, May 12, 2015 at 01:39:09AM +1000, Alexey Kardashevskiy wrote:
At the moment the DMA setup code looks for the "ibm,opal-tce-kill" property
which contains the TCE kill register address. Writes to this register
invalidates TCE cache on IODA/IODA2 hub.

This moves the register address from iommu_table to pnv_ioda_pe as:
1) When we get 2 tables per PE, this register will be used for both tables;
2) When we get TCE tables sharing, we will need to invalidate every
IOMMU group (i.e. PE) which is using this table and each PE has
its own invalidate register.

Actually, it's the virtual address of IO remapped PHB hardware register.
So it would be a property of PHB (struct pnv_phb). As the PE is connecting
with IOMMU table group. The virtual address can be retrieved by the path:
iommu_table -> iommu_table_group -> pnv_ioda_pe -> pnv_phb. However, I
don't insist and you have the best judge on it :-)

Are you suggesting moving pe->tce_inval_reg from pnv_ioda_pe to pnv_phb?

This moves the property reading/remapping code to a helper to reduce
code duplication. Although this change is not required for IODA1, this
changes it as well to reduce code duplication.

This adds a new pnv_pci_ioda2_tvt_invalidate() helper which invalidates
the entire table. It should be called after every call to
opal_pci_map_pe_dma_window(). It was not required before because
there is just a single TCE table and 64bit DMA is handled via bypass
window (which has no table so no chache is used) but this is going
to change with Dynamic DMA windows (DDW).

Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>

Reviewed-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx>


* fixed error from
* removed comment at "ibm,opal-tce-kill" parsing as irrelevant
* s/addr/val/ in pnv_pci_ioda2_tvt_invalidate() as it was not a kernel address

* new in the series
arch/powerpc/platforms/powernv/pci-ioda.c | 64 ++++++++++++++++++-------------
arch/powerpc/platforms/powernv/pci.h | 1 +
2 files changed, 39 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 35ab19c8..f972e40 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1680,7 +1680,7 @@ static void pnv_pci_ioda1_tce_invalidate(struct iommu_table *tbl,
struct pnv_ioda_pe, table_group);
__be64 __iomem *invalidate = rm ?
(__be64 __iomem *)pe->tce_inval_reg_phys :
- (__be64 __iomem *)tbl->it_index;
+ pe->tce_inval_reg;
unsigned long start, end, inc;
const unsigned shift = tbl->it_page_shift;

@@ -1751,6 +1751,18 @@ static struct iommu_table_ops pnv_ioda1_iommu_ops = {
.get = pnv_tce_get,

+static inline void pnv_pci_ioda2_tvt_invalidate(struct pnv_ioda_pe *pe)
+ /* 01xb - invalidate TCEs that match the specified PE# */
+ unsigned long val = (0x4ull << 60) | (pe->pe_number & 0xFF);
+ if (!pe->tce_inval_reg)
+ return;
+ mb(); /* Ensure above stores are visible */
+ __raw_writeq(cpu_to_be64(val), pe->tce_inval_reg);

The function name sounds it's to invalidate TVE cache. Actually, it's invalidting
TCE cache. So I guess the function name pnv_pci_ioda2_tce_invalidate() would be
more accurate.

TVT vs. TVE distinction is not clear for me, sorry :)

There is a function with exactly the same name as you proposed, below in this mail, it invalidates cache.
May be s/pnv_pci_ioda2_tvt_invalidate/pnv_pci_ioda2_invalidate_entire_cache/ ?

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