From: Nayna Jain <nayna@linux.ibm.com>

The Platform Keystore provides a signed update interface which can be used
to create, replace or append to certain variables in the PKS in a secure
fashion, with the hypervisor requiring that the update be signed using the
Platform Key.

Implement an interface to the H_PKS_SIGNED_UPDATE hcall in the plpks
driver to allow signed updates to PKS objects.

(The plpks driver doesn't need to do any cryptography or otherwise handle
the actual signed variable contents - that will be handled by userspace
tooling.)

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
[ajd: split patch, rewrite commit message, add timeout handling]
Co-developed-by: Andrew Donnellan <redacted>
Signed-off-by: Andrew Donnellan <redacted>
---
 arch/powerpc/include/asm/hvcall.h      |  3 +-
 arch/powerpc/platforms/pseries/plpks.c | 81 +++++++++++++++++++++++---
 arch/powerpc/platforms/pseries/plpks.h |  5 ++
 3 files changed, 79 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index 95fd7f9485d5..33b26c0cb69b 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h

@@ -336,7 +336,8 @@
 #define H_SCM_FLUSH		0x44C
 #define H_GET_ENERGY_SCALE_INFO	0x450
 #define H_WATCHDOG		0x45C
-#define MAX_HCALL_OPCODE	H_WATCHDOG
+#define H_PKS_SIGNED_UPDATE	0x454
+#define MAX_HCALL_OPCODE	H_PKS_SIGNED_UPDATE
 
 /* Scope args for H_SCM_UNBIND_ALL */
 #define H_UNBIND_SCOPE_ALL (0x1)

diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
index c5ae00a8a968..9e4401aabf4f 100644
--- a/arch/powerpc/platforms/pseries/plpks.c
+++ b/arch/powerpc/platforms/pseries/plpks.c

@@ -30,9 +30,9 @@
 #define MAX_NAME_SIZE	    239
 #define MAX_DATA_SIZE	    4000
 
-#define PKS_FLUSH_MAX_TIMEOUT 5000 //msec
-#define PKS_FLUSH_SLEEP	      10 //msec
-#define PKS_FLUSH_SLEEP_RANGE 400
+#define PKS_MAX_TIMEOUT		5000 // msec
+#define PKS_FLUSH_SLEEP		10 // msec
+#define PKS_FLUSH_SLEEP_RANGE	400
 
 static u8 *ospassword;
 static u16 ospasswordlength;

@@ -95,6 +95,12 @@ static int pseries_status_to_err(int rc)
 		err = -ENOENT;
 		break;
 	case H_BUSY:
+	case H_LONG_BUSY_ORDER_1_MSEC:
+	case H_LONG_BUSY_ORDER_10_MSEC:
+	case H_LONG_BUSY_ORDER_100_MSEC:
+	case H_LONG_BUSY_ORDER_1_SEC:
+	case H_LONG_BUSY_ORDER_10_SEC:
+	case H_LONG_BUSY_ORDER_100_SEC:
 		err = -EBUSY;
 		break;
 	case H_AUTHORITY:

@@ -198,14 +204,17 @@ static struct label *construct_label(char *component, u8 varos, u8 *name,
 				     u16 namelen)
 {
 	struct label *label;
-	size_t slen;
+	size_t slen = 0;
 
 	if (!name || namelen > MAX_NAME_SIZE)
 		return ERR_PTR(-EINVAL);
 
-	slen = strlen(component);
-	if (component && slen > sizeof(label->attr.prefix))
-		return ERR_PTR(-EINVAL);
+	// Support NULL component for signed updates
+	if (component) {
+		slen = strlen(component);
+		if (slen > sizeof(label->attr.prefix))
+			return ERR_PTR(-EINVAL);
+	}
 
 	// The label structure must not cross a page boundary, so we align to the next power of 2
 	label = kzalloc(roundup_pow_of_two(sizeof(*label)), GFP_KERNEL);

@@ -372,7 +381,7 @@ static int plpks_confirm_object_flushed(struct label *label,
 		usleep_range(PKS_FLUSH_SLEEP,
 			     PKS_FLUSH_SLEEP + PKS_FLUSH_SLEEP_RANGE);
 		timeout = timeout + PKS_FLUSH_SLEEP;
-	} while (timeout < PKS_FLUSH_MAX_TIMEOUT);
+	} while (timeout < PKS_MAX_TIMEOUT);
 
 	if (timed_out)
 		rc = -ETIMEDOUT;

@@ -382,6 +391,60 @@ static int plpks_confirm_object_flushed(struct label *label,
 	return rc;
 }
 
+int plpks_signed_update_var(struct plpks_var var, u64 flags)
+{