[PATCH v2 5/5] Show in sysfs if a memory node is able to do memory encryption

[Martin Fernandez <martin.fernandez@eclypsium.com>]

Show in each node in sysfs if its memory is able to do hardware memory
encryption, ie. if all its memory is marked with EFI_MEMORY_CPU_CRYPTO
in the EFI memory map.

This value will only be shown if the memory is local to at least one
CPU, since otherwise it won't be able to be encrypted by CPU's
cryptographic capabilities. This check is done against the ACPI's SRAT
table.

Signed-off-by: Martin Fernandez <martin.fernandez@eclypsium.com>
---
 Documentation/ABI/testing/sysfs-devices-node | 12 ++++
 arch/x86/include/asm/numa.h                  |  7 ++
 arch/x86/mm/numa.c                           |  5 ++
 arch/x86/mm/numa_emulation.c                 |  2 +-
 drivers/base/node.c                          | 72 +++++++++++++++++++-
 include/linux/node.h                         |  1 +
 6 files changed, 97 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-node

diff --git a/Documentation/ABI/testing/sysfs-devices-node b/Documentation/ABI/testing/sysfs-devices-node
new file mode 100644
index 000000000000..313fc4193977
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-node
@@ -0,0 +1,12 @@
+What:		/sys/devices/system/node/nodeX/crypto_capable
+Date:		October 2021
+Contact:	Martin Fernandez <martin.fernandez@eclypsium.com>
+Users:		fwupd
+Description:
+		This value is 1 if all system memory in this node is
+		marked with EFI_MEMORY_CPU_CRYPTO, indicating that the
+		system memory is capable of being protected with the
+		CPU’s memory cryptographic capabilities. It is 0
+		otherwise. This attribute will only be available if
+		node X is in ACPI's SRAT table or if it is an emulated
+		node.
diff --git a/arch/x86/include/asm/numa.h b/arch/x86/include/asm/numa.h
index e3bae2b60a0d..c3ed5c5be885 100644
--- a/arch/x86/include/asm/numa.h
+++ b/arch/x86/include/asm/numa.h
@@ -20,6 +20,13 @@
 #define NODE_MIN_SIZE (4*1024*1024)
 
 extern int numa_off;
+extern int emu_nid_to_phys[];
+
+/*
+ * used_dummy_numa_init indicates whether we used dummy_numa_init for
+ * initialization or not
+ */
+extern bool used_dummy_numa_init;
 
 /*
  * __apicid_to_node[] stores the raw mapping between physical apicid and
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 1e9b93b088db..f8d3a0d6bee1 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -20,6 +20,7 @@
 #include "numa_internal.h"
 
 int numa_off;
+bool used_dummy_numa_init;
 nodemask_t numa_nodes_parsed __initdata;
 
 struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
@@ -712,6 +713,8 @@ static int __init dummy_numa_init(void)
 	node_set(0, numa_nodes_parsed);
 	numa_add_memblk(0, 0, PFN_PHYS(max_pfn));
 
+	used_dummy_numa_init = true;
+
 	return 0;
 }
 
@@ -724,6 +727,8 @@ static int __init dummy_numa_init(void)
  */
 void __init x86_numa_init(void)
 {
+	used_dummy_numa_init = false;
+
 	if (!numa_off) {
 #ifdef CONFIG_ACPI_NUMA
 		if (!numa_init(x86_acpi_numa_init))
diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index e801e30089c4..f45bc30698e7 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -10,7 +10,7 @@
 
 #include "numa_internal.h"
 
-static int emu_nid_to_phys[MAX_NUMNODES];
+int emu_nid_to_phys[MAX_NUMNODES];
 static char *emu_cmdline __initdata;
 
 int __init numa_emu_cmdline(char *str)
diff --git a/drivers/base/node.c b/drivers/base/node.c
index c56d34f8158f..b2e1a8832fcf 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -5,6 +5,7 @@
 
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/acpi.h>
 #include <linux/mm.h>
 #include <linux/memory.h>
 #include <linux/vmstat.h>
@@ -560,11 +561,39 @@ static ssize_t node_read_distance(struct device *dev,
 }
 static DEVICE_ATTR(distance, 0444, node_read_distance, NULL);
 
+static ssize_t crypto_capable_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct pglist_data *pgdat = NODE_DATA(dev->id);
+
+	return sysfs_emit(buf, "%d\n", pgdat->crypto_capable);
+}
+static DEVICE_ATTR_RO(crypto_capable);
+
+static umode_t node_attr_is_visible(struct kobject *kobj,
+				    struct attribute *attr, int n)
+{
+	umode_t result = 0;
+
+	if (attr == &dev_attr_crypto_capable.attr) {
+		const struct device *const dev =
+			container_of(kobj, struct device, kobj);
+		const int nid = dev->id;
+
+		if (node_devices[nid]->cpu_local)
+			result = attr->mode;
+		/* else: hide the attribute */
+	}
+
+	return result;
+}
+
 static struct attribute *node_dev_attrs[] = {
 	&dev_attr_meminfo.attr,
 	&dev_attr_numastat.attr,
 	&dev_attr_distance.attr,
 	&dev_attr_vmstat.attr,
+	&dev_attr_crypto_capable.attr,
 	NULL
 };
 
@@ -576,7 +605,8 @@ static struct bin_attribute *node_dev_bin_attrs[] = {
 
 static const struct attribute_group node_dev_group = {
 	.attrs = node_dev_attrs,
-	.bin_attrs = node_dev_bin_attrs
+	.bin_attrs = node_dev_bin_attrs,
+	.is_visible = node_attr_is_visible,
 };
 
 static const struct attribute_group *node_dev_groups[] = {
@@ -972,6 +1002,44 @@ static void init_node_hugetlb_work(int nid) { }
 
 #endif
 
+#ifdef CONFIG_NUMA
+#ifdef CONFIG_NUMA_EMU
+static int get_real_nid(int nid)
+{
+	return emu_nid_to_phys[nid];
+}
+#else
+static int get_real_nid(int nid)
+{
+	return nid;
+}
+#endif /* CONFIG_NUMA_EMU */
+
+static void set_cpu_local(int nid)
+{
+	const int real_nid = get_real_nid(nid);
+	bool cpu_local;
+
+	/*
+	 * If we have the SRAT table available we need to check it
+	 * otherwise it's enough to check if real_nid is 0
+	 */
+#ifdef CONFIG_ACPI_NUMA
+	cpu_local =
+		used_dummy_numa_init ? real_nid == 0 : node_to_pxm(real_nid) != PXM_INVAL;
+#else
+	cpu_local = real_nid == 0;
+#endif
+
+	node_devices[nid]->cpu_local = cpu_local;
+}
+#else
+static void set_cpu_local(nid)
+{
+	node_devices[nid]->cpu_local = true;
+}
+#endif /* CONFIG_NUMA */
+
 int __register_one_node(int nid)
 {
 	int error;
@@ -981,6 +1049,8 @@ int __register_one_node(int nid)
 	if (!node_devices[nid])
 		return -ENOMEM;
 
+	set_cpu_local(nid);
+
 	error = register_node(node_devices[nid], nid);
 
 	/* link cpu under this node */
diff --git a/include/linux/node.h b/include/linux/node.h
index 8e5a29897936..d32653fac39e 100644
--- a/include/linux/node.h
+++ b/include/linux/node.h
@@ -92,6 +92,7 @@ struct node {
 	struct list_head cache_attrs;
 	struct device *cache_dev;
 #endif
+	bool cpu_local;
 };
 
 struct memory_block;
-- 
2.30.2