[Skiboot] [PATCH v2] core/init: Add ibm, processor-storage-keys property to /cpus DT node.

Thiago Jung Bauermann bauerman at linux.vnet.ibm.com
Sat Sep 9 08:31:02 AEST 2017

LoPAPR says:


    property name indicating the number of virtual storage keys supported
    by the processor described by this node.

    prop-encoded-array: Consists of two cells encoded as with encode-int.
    The first cell represents the number of virtual storage keys supported
    for data accesses while the second cell represents the number of
    virtual storage keys supported for instruction accesses. The cell value
    of zero indicates that no storage keys are supported for the access

pHyp provides the property above but there's a bug in P8 firmware where the
second cell is zero even though POWER8 supports instruction access keys.
This bug will be fixed for P9.

While this is a PAPR property, it's useful to have it in powernv as well
so that Linux has a uniform way of checking for the feature regardless of
the platform it's running on.

On PAPR there is one property for each CPU node, but since it's highly
unlikely that different CPUs will support a different number of keys, we
put the property in the /cpus node instead.

Tested on QEMU POWER8 powernv model and Mambo P9.

Signed-off-by: Thiago Jung Bauermann <bauerman at linux.vnet.ibm.com>
 core/init.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Changes in v2:
- Put property in /cpus instead of in each CPU node.

diff --git a/core/init.c b/core/init.c
index 8951e17b4c90..4a6f9155511d 100644
--- a/core/init.c
+++ b/core/init.c
@@ -563,6 +563,22 @@ void __noreturn load_and_boot_kernel(bool is_reboot)
 	start_kernel(kernel_entry, fdt, mem_top);
+static void storage_keys_fixup(void)
+	/* P7 doesn't support instruction access keys. */
+	const u32 insn_keys = (proc_gen == proc_gen_p7) ? 0 : 32;
+	struct dt_node *cpus = dt_find_by_path(dt_root, "/cpus");
+	assert(cpus);
+	if (proc_gen == proc_gen_unknown)
+		return;
+	else if (dt_has_node_property(cpus, "ibm,processor-storage-keys", NULL))
+		return;
+	dt_add_property_cells(cpus, "ibm,processor-storage-keys", 32, insn_keys);
 static void dt_fixups(void)
 	struct dt_node *n;
@@ -590,6 +606,8 @@ static void dt_fixups(void)
 		if (!dt_has_node_property(n, "scom-controller", NULL))
 			dt_add_property(n, "scom-controller", NULL, 0);
+	storage_keys_fixup();
 static void add_arch_vector(void)

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