[PATCH kernel] powerpc/ioda: Use ibm, supported-tce-sizes for IOMMU page size mask

At the moment we assume that IODA2 and newer PHBs can always do 4K/64K/16M
IOMMU pages, however this is not the case for POWER9 and now skiboot
advertises the supported sizes via the device so we use that instead
of hard coding the mask.

This falls back to the default mask if no "ibm,supported-tce-sizes"
is provided. This removes 16MB from the defaults as it is not supported
everywhere; the downside of this is that hugepages backed POWER8 guests
will fall back to 64K IOMMU pages until skiboot is updated.

Signed-off-by: Alexey Kardashevskiy <redacted>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 3f9c69d..e02a8a9 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c

@@ -2910,6 +2910,24 @@ static void pnv_pci_ioda2_table_free_pages(struct iommu_table *tbl)
 			tbl->it_indirect_levels);
 }
 
+static unsigned long pnv_ioda_parse_tce_sizes(struct pnv_phb *phb)
+{
+	struct pci_controller *hose = phb->hose;
+	struct device_node *dn = hose->dn;
+	int i, len = 0;
+	const __be32 *r;
+	unsigned long mask = 0;
+
+	r = of_get_property(dn, "ibm,supported-tce-sizes", &len);
+	if (!r || !len)
+		return SZ_4K | SZ_64K;
+
+	for (i = 0; i < len / sizeof(*r); ++i)
+		mask |= 1ULL << be32_to_cpu(r[i]);
+
+	return mask;
+}
+
 static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
 				       struct pnv_ioda_pe *pe)
 {

@@ -2934,7 +2952,7 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
 	pe->table_group.max_dynamic_windows_supported =
 			IOMMU_TABLE_GROUP_MAX_TABLES;
 	pe->table_group.max_levels = POWERNV_IOMMU_MAX_LEVELS;
-	pe->table_group.pgsizes = SZ_4K | SZ_64K | SZ_16M;
+	pe->table_group.pgsizes = pnv_ioda_parse_tce_sizes(phb);
 #ifdef CONFIG_IOMMU_API
 	pe->table_group.ops = &pnv_pci_ioda2_ops;
 #endif

-- 
2.11.0

Alexey Kardashevskiy [off-list ref] writes:

At the moment we assume that IODA2 and newer PHBs can always do 4K/64K/16M
IOMMU pages, however this is not the case for POWER9 and now skiboot
advertises the supported sizes via the device so we use that instead
of hard coding the mask.

This falls back to the default mask if no "ibm,supported-tce-sizes"
is provided. This removes 16MB from the defaults as it is not supported
everywhere; the downside of this is that hugepages backed POWER8 guests
will fall back to 64K IOMMU pages until skiboot is updated.

That's probably not really an acceptable solution is it?

I think we need to add a quirk if we're on power8 to put 16M back.

cheers

On Wed, 2018-05-02 at 16:12 +1000, Alexey Kardashevskiy wrote:

At the moment we assume that IODA2 and newer PHBs can always do
4K/64K/16M
IOMMU pages, however this is not the case for POWER9 and now skiboot
advertises the supported sizes via the device so we use that instead
of hard coding the mask.

This falls back to the default mask if no "ibm,supported-tce-sizes"
is provided. This removes 16MB from the defaults as it is not
supported
everywhere; the downside of this is that hugepages backed POWER8
guests
will fall back to 64K IOMMU pages until skiboot is updated.

Signed-off-by: Alexey Kardashevskiy <redacted>

Reviewed-by: Russell Currey <redacted>