13986 usmn(7D) could support writing

Reviewed by: Gergő Mihály Doma <domag02@gmail.com> Reviewed by: C Fraire <cfraire@me.com> Reviewed by: Andy Fiddaman <andy@omnios.org> Approved by: Richard Lowe <richlowe@richlowe.net>
illumos · Aug 2, 2021 · f198607 · f198607
1 parent 8efb738
commit f198607
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Showing 5 changed files with 112 additions and 30 deletions.
diff --git a/usr/src/cmd/amdzen/usmn.c b/usr/src/cmd/amdzen/usmn.c
@@ -10,7 +10,7 @@
  */
 
 /*
- * Copyright 2020 Oxide Computer Company
+ * Copyright 2021 Oxide Computer Company
  */
 
 /*
@@ -28,28 +28,46 @@
 #include <usmn.h>
 
 static boolean_t
-usmn_read(int fd, const char *addr)
+usmn_parse_uint32(const char *str, uint32_t *valp)
 {
-	unsigned long long l;
+	long long l;
 	char *eptr;
-	usmn_reg_t usr;
 
 	errno = 0;
-	l = strtoull(addr, &eptr, 16);
-	if (errno != 0 || *eptr != '\0' || l > UINT32_MAX) {
-		warnx("failed to parse %s: invalid string or address", addr);
+	l = strtoll(str, &eptr, 16);
+	if (errno != 0 || *eptr != '\0') {
+		warnx("failed to parse string '%s'", str);
 		return (B_FALSE);
 	}
 
-	usr.usr_addr = (uint32_t)l;
-	usr.usr_data = 0;
+	if (l < 0 || l > UINT32_MAX) {
+		warnx("value %s is outside the valid range [0, UINT32_MAX]",
+		    str);
+		return (B_FALSE);
+	}
+
+	*valp = (uint32_t)l;
+	return (B_TRUE);
+}
+
+static boolean_t
+usmn_op(boolean_t do_write, int fd, const char *addr, uint32_t value)
+{
+	usmn_reg_t usr;
+
+	usr.usr_data = value;
+	if (!usmn_parse_uint32(addr, &usr.usr_addr)) {
+		return (B_FALSE);
+	}
 
-	if (ioctl(fd, USMN_READ, &usr) != 0) {
-		warn("failed to read SMN at 0x%x", usr.usr_addr);
+	if (ioctl(fd, do_write ? USMN_WRITE : USMN_READ, &usr) != 0) {
+		warn("SMN ioctl failed at 0x%x", usr.usr_addr);
 		return (B_FALSE);
 	}
 
-	(void) printf("0x%x: 0x%x\n", usr.usr_addr, usr.usr_data);
+	if (!do_write) {
+		(void) printf("0x%x: 0x%x\n", usr.usr_addr, usr.usr_data);
+	}
 	return (B_TRUE);
 }
 
@@ -58,15 +76,23 @@ main(int argc, char *argv[])
 {
 	int i, c, fd, ret;
 	const char *device = NULL;
+	boolean_t do_write = B_FALSE;
+	uint32_t wval = 0;
 
-	while ((c = getopt(argc, argv, "d:")) != -1) {
+	while ((c = getopt(argc, argv, "d:w:")) != -1) {
 		switch (c) {
 		case 'd':
 			device = optarg;
 			break;
+		case 'w':
+			do_write = B_TRUE;
+			if (!usmn_parse_uint32(optarg, &wval)) {
+				return (EXIT_FAILURE);
+			}
+			break;
 		default:
-			(void) fprintf(stderr, "Usage: usmn -d device addr "
-			    "[addr]...\n"
+			(void) fprintf(stderr, "Usage: usmn -d device "
+			    "[-w value] addr [addr]...\n"
 			    "Note: All addresses are interpreted as hex\n");
 			return (2);
 		}
@@ -80,21 +106,24 @@ main(int argc, char *argv[])
 	argv += optind;
 
 	if (argc == 0) {
-		errx(EXIT_FAILURE, "missing registers to read");
+		errx(EXIT_FAILURE, "at least one register must be specified");
+	}
+
+	if (do_write && argc != 1) {
+		errx(EXIT_FAILURE, "can only write to a single register");
 	}
 
-	if ((fd = open(device, O_RDONLY)) < 0) {
+	if ((fd = open(device, do_write ? O_RDWR : O_RDONLY)) < 0) {
 		err(EXIT_FAILURE, "failed to open %s", device);
 	}
 
 	ret = EXIT_SUCCESS;
 	for (i = 0; i < argc; i++) {
-		if (!usmn_read(fd, argv[i])) {
+		if (!usmn_op(do_write, fd, argv[i], wval)) {
 			ret = EXIT_FAILURE;
 		}
 	}
 
 	(void) close(fd);
-
 	return (ret);
 }
diff --git a/usr/src/man/man7d/usmn.7d b/usr/src/man/man7d/usmn.7d
@@ -9,9 +9,9 @@
 .\" http://www.illumos.org/license/CDDL.
 .\"
 .\"
-.\" Copyright 2020 Oxide Computer Company
+.\" Copyright 2021 Oxide Computer Company
 .\"
-.Dd September 1, 2020
+.Dd July 30, 2021
 .Dt USMN 7D
 .Os
 .Sh NAME
@@ -22,16 +22,21 @@
 .Sh DESCRIPTION
 The
 .Nm
-driver provides the ability to read data from the AMD system management
-network
+driver provides the ability to read and write data from the AMD System
+Management Network
 .Pq SMN
 on AMD Family 17h
 .Pq Zen, Zen+, and Zen 2
+and AMD Family 19h
+.Pq Zen 3
 processors.
 .Pp
 This driver is intended strictly for facilitating platform development
-and is not recommended for systems that aren't doing kernel development
-on AMD Zen platforms.
+and is not recommended for systems that aren't doing kernel and platform
+development on AMD Zen platforms.
+Arbitrary writes to the SMN can severely damage and destabilize the system.
+If you do not need access to the SMN, then this driver should not be
+present on the system.
 .Sh SEE ALSO
 .Xr amdzen 7D ,
 .Xr zen_udf 7D
diff --git a/usr/src/uts/intel/io/amdzen/amdzen.c b/usr/src/uts/intel/io/amdzen/amdzen.c
@@ -11,7 +11,7 @@
 
 /*
  * Copyright 2019, Joyent, Inc.
- * Copyright 2020 Oxide Computer Company
+ * Copyright 2021 Oxide Computer Company
  */
 
 /*
@@ -213,7 +213,6 @@ amdzen_df_read64(amdzen_t *azn, amdzen_df_t *df, uint8_t inst, uint8_t func,
 	return (amdzen_stub_get64(df->adf_funcs[4], AMDZEN_DF_F4_FICAD_LO));
 }
 
-
 static uint32_t
 amdzen_smn_read32(amdzen_t *azn, amdzen_df_t *df, uint32_t reg)
 {
@@ -222,6 +221,14 @@ amdzen_smn_read32(amdzen_t *azn, amdzen_df_t *df, uint32_t reg)
 	return (amdzen_stub_get32(df->adf_nb, AMDZEN_NB_SMN_DATA));
 }
 
+static void
+amdzen_smn_write32(amdzen_t *azn, amdzen_df_t *df, uint32_t reg, uint32_t val)
+{
+	VERIFY(MUTEX_HELD(&azn->azn_mutex));
+	amdzen_stub_put32(df->adf_nb, AMDZEN_NB_SMN_ADDR, reg);
+	amdzen_stub_put32(df->adf_nb, AMDZEN_NB_SMN_DATA, val);
+}
+
 static amdzen_df_t *
 amdzen_df_find(amdzen_t *azn, uint_t dfno)
 {
@@ -273,6 +280,30 @@ amdzen_c_smn_read32(uint_t dfno, uint32_t reg, uint32_t *valp)
 	return (0);
 }
 
+int
+amdzen_c_smn_write32(uint_t dfno, uint32_t reg, uint32_t val)
+{
+	amdzen_df_t *df;
+	amdzen_t *azn = amdzen_data;
+
+	mutex_enter(&azn->azn_mutex);
+	df = amdzen_df_find(azn, dfno);
+	if (df == NULL) {
+		mutex_exit(&azn->azn_mutex);
+		return (ENOENT);
+	}
+
+	if ((df->adf_flags & AMDZEN_DF_F_FOUND_NB) == 0) {
+		mutex_exit(&azn->azn_mutex);
+		return (ENXIO);
+	}
+
+	amdzen_smn_write32(azn, df, reg, val);
+	mutex_exit(&azn->azn_mutex);
+	return (0);
+}
+
+
 uint_t
 amdzen_c_df_count(void)
 {

diff --git a/usr/src/uts/intel/io/amdzen/amdzen_client.h b/usr/src/uts/intel/io/amdzen/amdzen_client.h
@@ -10,7 +10,7 @@
  */
 
 /*
- * Copyright 2020 Oxide Computer Company
+ * Copyright 2021 Oxide Computer Company
  */
 
 #ifndef _AMDZEN_CLIENT_H
@@ -27,6 +27,7 @@ extern "C" {
 #endif
 
 extern int amdzen_c_smn_read32(uint_t, uint32_t, uint32_t *);
+extern int amdzen_c_smn_write32(uint_t, uint32_t, uint32_t);
 extern uint_t amdzen_c_df_count(void);
 extern int amdzen_c_df_read32(uint_t, uint8_t, uint8_t, uint16_t, uint32_t *);
 extern int amdzen_c_df_read64(uint_t, uint8_t, uint8_t, uint16_t, uint64_t *);

diff --git a/usr/src/uts/intel/io/amdzen/usmn.c b/usr/src/uts/intel/io/amdzen/usmn.c
@@ -10,7 +10,7 @@
  */
 
 /*
- * Copyright 2020 Oxide Computer Company
+ * Copyright 2021 Oxide Computer Company
  */
 
 /*
@@ -97,15 +97,31 @@ usmn_ioctl(dev_t dev, int cmd, intptr_t arg, int mode, cred_t *credp,
 	if (cmd == USMN_READ) {
 		int ret;
 
+		if ((mode & FREAD) == 0) {
+			return (EINVAL);
+		}
+
 		ret = amdzen_c_smn_read32(dfno, usr.usr_addr, &usr.usr_data);
 		if (ret != 0) {
 			return (ret);
 		}
+	} else if (cmd == USMN_WRITE) {
+		int ret;
+
+		if ((mode & FWRITE) == 0) {
+			return (EINVAL);
+		}
+
+		ret = amdzen_c_smn_write32(dfno, usr.usr_addr, usr.usr_data);
+		if (ret != 0) {
+			return (ret);
+		}
 	} else {
 		return (ENOTSUP);
 	}
 
-	if (ddi_copyout(&usr, (void *)arg, sizeof (usr), mode & FKIOCTL) != 0) {
+	if (cmd == USMN_READ &&
+	    ddi_copyout(&usr, (void *)arg, sizeof (usr), mode & FKIOCTL) != 0) {
 		return (EFAULT);
 	}