The main part of this branch is the ongoing fight against windmills in

an attempt to have userspace tools not poke at naked MSRs. This round
 deals with MSR_IA32_ENERGY_PERF_BIAS and removes direct poking into it
 by our in-tree tools in favor of the proper "energy_perf_bias" sysfs
 interface which we already have.
 
 In addition, the msr.ko write filtering's error message points to a new
 summary page which contains the info we collected from helpful reporters
 about which userspace tools write MSRs:
 
   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/about
 
 along with the current status of their conversion.
 
 Rest is the usual small fixes and improvements.
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Merge tag 'x86_misc_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull misc x86 updates from Borislav Petkov:
 "The main part of this branch is the ongoing fight against windmills in
  an attempt to have userspace tools not poke at naked MSRs.

  This round deals with MSR_IA32_ENERGY_PERF_BIAS and removes direct
  poking into it by our in-tree tools in favor of the proper
  "energy_perf_bias" sysfs interface which we already have.

  In addition, the msr.ko write filtering's error message points to a
  new summary page which contains the info we collected from helpful
  reporters about which userspace tools write MSRs:

      https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/about

  along with the current status of their conversion.

  The rest is the usual small fixes and improvements"

* tag 'x86_misc_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/msr: Add a pointer to an URL which contains further details
  x86/pci: Fix the function type for check_reserved_t
  selftests/x86: Add missing .note.GNU-stack sections
  selftests/x86/fsgsbase: Fix GS == 1, 2, and 3 tests
  x86/msr: Downgrade unrecognized MSR message
  x86/msr: Do not allow writes to MSR_IA32_ENERGY_PERF_BIAS
  tools/power/x86_energy_perf_policy: Read energy_perf_bias from sysfs
  tools/power/turbostat: Read energy_perf_bias from sysfs
  tools/power/cpupower: Read energy_perf_bias from sysfs
  MAINTAINERS: Cleanup SGI-related entries

MAINTAINERS

@@ -15905,13 +15905,14 @@ F:	include/linux/sfp.h
 K:	phylink\.h|struct\s+phylink|\.phylink|>phylink_|phylink_(autoneg|clear|connect|create|destroy|disconnect|ethtool|helper|mac|mii|of|set|start|stop|test|validate)
 
 SGI GRU DRIVER
-M:	Dimitri Sivanich <sivanich@sgi.com>
+M:	Dimitri Sivanich <dimitri.sivanich@hpe.com>
 S:	Maintained
 F:	drivers/misc/sgi-gru/
 
 SGI XP/XPC/XPNET DRIVER
-M:	Cliff Whickman <cpw@sgi.com>
 M:	Robin Holt <robinmholt@gmail.com>
+M:	Steve Wahl <steve.wahl@hpe.com>
+R:	Mike Travis <mike.travis@hpe.com>
 S:	Maintained
 F:	drivers/misc/sgi-xp/
 
@@ -19166,6 +19167,7 @@ F:	arch/x86/platform
 
 X86 PLATFORM UV HPE SUPERDOME FLEX
 M:	Steve Wahl <steve.wahl@hpe.com>
+R:	Mike Travis <mike.travis@hpe.com>
 R:	Dimitri Sivanich <dimitri.sivanich@hpe.com>
 R:	Russ Anderson <russ.anderson@hpe.com>
 S:	Supported

arch/x86/kernel/msr.c

@@ -99,11 +99,9 @@ static int filter_write(u32 reg)
 	if (!__ratelimit(&fw_rs))
 		return 0;
 
-	if (reg == MSR_IA32_ENERGY_PERF_BIAS)
-		return 0;
-
-	pr_err("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@kernel.org.\n",
-	       reg, current->comm, current->pid);
+	pr_warn("Write to unrecognized MSR 0x%x by %s (pid: %d).\n",
+	        reg, current->comm, current->pid);
+	pr_warn("See https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/about for details.\n");
 
 	return 0;
 }

arch/x86/pci/mmconfig-shared.c

@@ -425,7 +425,7 @@ static acpi_status find_mboard_resource(acpi_handle handle, u32 lvl,
 	return AE_OK;
 }
 
-static bool is_acpi_reserved(u64 start, u64 end, unsigned not_used)
+static bool is_acpi_reserved(u64 start, u64 end, enum e820_type not_used)
 {
 	struct resource mcfg_res;
 
@@ -442,7 +442,7 @@ static bool is_acpi_reserved(u64 start, u64 end, unsigned not_used)
 	return mcfg_res.flags;
 }
 
-typedef bool (*check_reserved_t)(u64 start, u64 end, unsigned type);
+typedef bool (*check_reserved_t)(u64 start, u64 end, enum e820_type type);
 
 static bool __ref is_mmconf_reserved(check_reserved_t is_reserved,
 				     struct pci_mmcfg_region *cfg,

tools/power/cpupower/lib/cpupower.c

@@ -16,8 +16,8 @@
 
 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
 {
-	int fd;
 	ssize_t numread;
+	int fd;
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)
@@ -35,6 +35,27 @@ unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
 	return (unsigned int) numread;
 }
 
+unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)
+{
+	ssize_t numwritten;
+	int fd;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return 0;
+
+	numwritten = write(fd, buf, buflen - 1);
+	if (numwritten < 1) {
+		perror(path);
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+
+	return (unsigned int) numwritten;
+}
+
 /*
  * Detect whether a CPU is online
  *

tools/power/cpupower/lib/cpupower_intern.h

@@ -1,6 +1,11 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #define PATH_TO_CPU "/sys/devices/system/cpu/"
+
+#ifndef MAX_LINE_LEN
 #define MAX_LINE_LEN 4096
+#endif
+
 #define SYSFS_PATH_MAX 255
 
 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen);
+unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen);

tools/power/cpupower/utils/cpupower-info.c

@@ -101,7 +101,7 @@ int cmd_info(int argc, char **argv)
 		}
 
 		if (params.perf_bias) {
-			ret = msr_intel_get_perf_bias(cpu);
+			ret = cpupower_intel_get_perf_bias(cpu);
 			if (ret < 0) {
 				fprintf(stderr,
 			_("Could not read perf-bias value[%d]\n"), ret);

tools/power/cpupower/utils/cpupower-set.c

@@ -95,7 +95,7 @@ int cmd_set(int argc, char **argv)
 		}
 
 		if (params.perf_bias) {
-			ret = msr_intel_set_perf_bias(cpu, perf_bias);
+			ret = cpupower_intel_set_perf_bias(cpu, perf_bias);
 			if (ret) {
 				fprintf(stderr, _("Error setting perf-bias "
 						  "value on CPU %d\n"), cpu);

tools/power/cpupower/utils/helpers/helpers.h

@@ -105,8 +105,8 @@ extern struct cpupower_cpu_info cpupower_cpu_info;
 extern int read_msr(int cpu, unsigned int idx, unsigned long long *val);
 extern int write_msr(int cpu, unsigned int idx, unsigned long long val);
 
-extern int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val);
-extern int msr_intel_get_perf_bias(unsigned int cpu);
+extern int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val);
+extern int cpupower_intel_get_perf_bias(unsigned int cpu);
 extern unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu);
 
 /* Read/Write msr ****************************/
@@ -150,9 +150,9 @@ static inline int read_msr(int cpu, unsigned int idx, unsigned long long *val)
 { return -1; };
 static inline int write_msr(int cpu, unsigned int idx, unsigned long long val)
 { return -1; };
-static inline int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
+static inline int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
 { return -1; };
-static inline int msr_intel_get_perf_bias(unsigned int cpu)
+static inline int cpupower_intel_get_perf_bias(unsigned int cpu)
 { return -1; };
 static inline unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
 { return 0; };

tools/power/cpupower/utils/helpers/misc.c

@@ -1,7 +1,15 @@
 // SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+
 #if defined(__i386__) || defined(__x86_64__)
 
 #include "helpers/helpers.h"
+#include "helpers/sysfs.h"
+
+#include "cpupower_intern.h"
 
 #define MSR_AMD_HWCR	0xc0010015
 
@@ -40,4 +48,44 @@ int cpufreq_has_boost_support(unsigned int cpu, int *support, int *active,
 		*support = *active = 1;
 	return 0;
 }
+
+int cpupower_intel_get_perf_bias(unsigned int cpu)
+{
+	char linebuf[MAX_LINE_LEN];
+	char path[SYSFS_PATH_MAX];
+	unsigned long val;
+	char *endp;
+
+	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+
+	if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
+		return -1;
+
+	val = strtol(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return -1;
+
+	return val;
+}
+
+int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[3] = {};
+
+	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+	snprintf(linebuf, sizeof(linebuf), "%d", val);
+
+	if (cpupower_write_sysfs(path, linebuf, 3) <= 0)
+		return -1;
+
+	return 0;
+}
+
 #endif /* #if defined(__i386__) || defined(__x86_64__) */

tools/power/cpupower/utils/helpers/msr.c

@@ -11,7 +11,6 @@
 /* Intel specific MSRs */
 #define MSR_IA32_PERF_STATUS		0x198
 #define MSR_IA32_MISC_ENABLES		0x1a0
-#define MSR_IA32_ENERGY_PERF_BIAS	0x1b0
 #define MSR_NEHALEM_TURBO_RATIO_LIMIT	0x1ad
 
 /*
@@ -73,33 +72,6 @@ int write_msr(int cpu, unsigned int idx, unsigned long long val)
 	return -1;
 }
 
-int msr_intel_get_perf_bias(unsigned int cpu)
-{
-	unsigned long long val;
-	int ret;
-
-	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
-		return -1;
-
-	ret = read_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &val);
-	if (ret)
-		return ret;
-	return val;
-}
-
-int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
-{
-	int ret;
-
-	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
-		return -1;
-
-	ret = write_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, val);
-	if (ret)
-		return ret;
-	return 0;
-}
-
 unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
 {
 	unsigned long long val;

tools/power/x86/turbostat/turbostat.c

@@ -1831,6 +1831,25 @@ int get_mp(int cpu, struct msr_counter *mp, unsigned long long *counterp)
 	return 0;
 }
 
+int get_epb(int cpu)
+{
+	char path[128 + PATH_BYTES];
+	int ret, epb = -1;
+	FILE *fp;
+
+	sprintf(path, "/sys/devices/system/cpu/cpu%d/power/energy_perf_bias", cpu);
+
+	fp = fopen_or_die(path, "r");
+
+	ret = fscanf(fp, "%d", &epb);
+	if (ret != 1)
+		err(1, "%s(%s)", __func__, path);
+
+	fclose(fp);
+
+	return epb;
+}
+
 void get_apic_id(struct thread_data *t)
 {
 	unsigned int eax, ebx, ecx, edx;
@@ -3917,9 +3936,8 @@ dump_sysfs_pstate_config(void)
  */
 int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 {
-	unsigned long long msr;
 	char *epb_string;
-	int cpu;
+	int cpu, epb;
 
 	if (!has_epb)
 		return 0;
@@ -3935,10 +3953,11 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		return -1;
 	}
 
-	if (get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr))
+	epb = get_epb(cpu);
+	if (epb < 0)
 		return 0;
 
-	switch (msr & 0xF) {
+	switch (epb) {
 	case ENERGY_PERF_BIAS_PERFORMANCE:
 		epb_string = "performance";
 		break;
@@ -3952,7 +3971,7 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 		epb_string = "custom";
 		break;
 	}
-	fprintf(outf, "cpu%d: MSR_IA32_ENERGY_PERF_BIAS: 0x%08llx (%s)\n", cpu, msr, epb_string);
+	fprintf(outf, "cpu%d: EPB: %d (%s)\n", cpu, epb, epb_string);
 
 	return 0;
 }

tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c

@@ -91,6 +91,9 @@ unsigned int has_hwp_request_pkg;	/* IA32_HWP_REQUEST_PKG */
 
 unsigned int bdx_highest_ratio;
 
+#define PATH_TO_CPU "/sys/devices/system/cpu/"
+#define SYSFS_PATH_MAX 255
+
 /*
  * maintain compatibility with original implementation, but don't document it:
  */
@@ -721,6 +724,48 @@ int put_msr(int cpu, int offset, unsigned long long new_msr)
 	return 0;
 }
 
+static unsigned int read_sysfs(const char *path, char *buf, size_t buflen)
+{
+	ssize_t numread;
+	int fd;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	numread = read(fd, buf, buflen - 1);
+	if (numread < 1) {
+		close(fd);
+		return 0;
+	}
+
+	buf[numread] = '\0';
+	close(fd);
+
+	return (unsigned int) numread;
+}
+
+static unsigned int write_sysfs(const char *path, char *buf, size_t buflen)
+{
+	ssize_t numwritten;
+	int fd;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return 0;
+
+	numwritten = write(fd, buf, buflen - 1);
+	if (numwritten < 1) {
+		perror("write failed\n");
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+
+	return (unsigned int) numwritten;
+}
+
 void print_hwp_cap(int cpu, struct msr_hwp_cap *cap, char *str)
 {
 	if (cpu != -1)
@@ -798,17 +843,61 @@ void write_hwp_request(int cpu, struct msr_hwp_request *hwp_req, unsigned int ms
 	put_msr(cpu, msr_offset, msr);
 }
 
+static int get_epb(int cpu)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[3];
+	char *endp;
+	long val;
+
+	if (!has_epb)
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+
+	if (!read_sysfs(path, linebuf, 3))
+		return -1;
+
+	val = strtol(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return -1;
+
+	return (int)val;
+}
+
+static int set_epb(int cpu, int val)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[3];
+	char *endp;
+	int ret;
+
+	if (!has_epb)
+		return -1;
+
+	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/power/energy_perf_bias", cpu);
+	snprintf(linebuf, sizeof(linebuf), "%d", val);
+
+	ret = write_sysfs(path, linebuf, 3);
+	if (ret <= 0)
+		return -1;
+
+	val = strtol(linebuf, &endp, 0);
+	if (endp == linebuf || errno == ERANGE)
+		return -1;
+
+	return (int)val;
+}
+
 int print_cpu_msrs(int cpu)
 {
-	unsigned long long msr;
 	struct msr_hwp_request req;
 	struct msr_hwp_cap cap;
+	int epb;
 
-	if (has_epb) {
-		get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr);
-
-		printf("cpu%d: EPB %u\n", cpu, (unsigned int) msr);
-	}
+	epb = get_epb(cpu);
+	if (epb >= 0)
+		printf("cpu%d: EPB %u\n", cpu, (unsigned int) epb);
 
 	if (!has_hwp)
 		return 0;
@@ -1091,15 +1180,15 @@ int enable_hwp_on_cpu(int cpu)
 int update_cpu_msrs(int cpu)
 {
 	unsigned long long msr;
-
+	int epb;
 
 	if (update_epb) {
-		get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr);
-		put_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, new_epb);
+		epb = get_epb(cpu);
+		set_epb(cpu, new_epb);
 
 		if (verbose)
 			printf("cpu%d: ENERGY_PERF_BIAS old: %d new: %d\n",
-				cpu, (unsigned int) msr, (unsigned int) new_epb);
+				cpu, epb, (unsigned int) new_epb);
 	}
 
 	if (update_turbo) {

tools/testing/selftests/x86/fsgsbase.c

@@ -392,8 +392,8 @@ static void set_gs_and_switch_to(unsigned long local,
 		local = read_base(GS);
 
 		/*
-		 * Signal delivery seems to mess up weird selectors.  Put it
-		 * back.
+		 * Signal delivery is quite likely to change a selector
+		 * of 1, 2, or 3 back to 0 due to IRET being defective.
 		 */
 		asm volatile ("mov %0, %%gs" : : "rm" (force_sel));
 	} else {
@@ -411,6 +411,14 @@ static void set_gs_and_switch_to(unsigned long local,
 	if (base == local && sel_pre_sched == sel_post_sched) {
 		printf("[OK]\tGS/BASE remained 0x%hx/0x%lx\n",
 		       sel_pre_sched, local);
+	} else if (base == local && sel_pre_sched >= 1 && sel_pre_sched <= 3 &&
+		   sel_post_sched == 0) {
+		/*
+		 * IRET is misdesigned and will squash selectors 1, 2, or 3
+		 * to zero.  Don't fail the test just because this happened.
+		 */
+		printf("[OK]\tGS/BASE changed from 0x%hx/0x%lx to 0x%hx/0x%lx because IRET is defective\n",
+		       sel_pre_sched, local, sel_post_sched, base);
 	} else {
 		nerrs++;
 		printf("[FAIL]\tGS/BASE changed from 0x%hx/0x%lx to 0x%hx/0x%lx\n",

tools/testing/selftests/x86/raw_syscall_helper_32.S

@@ -45,3 +45,5 @@ int80_and_ret:
 
 	.type int80_and_ret, @function
 	.size int80_and_ret, .-int80_and_ret
+
+.section .note.GNU-stack,"",%progbits

tools/testing/selftests/x86/thunks.S

@@ -57,3 +57,5 @@ call32_from_64:
 	ret
 
 .size call32_from_64, .-call32_from_64
+
+.section .note.GNU-stack,"",%progbits