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

3 files changed, 14 insertions, 2 deletions

diff --git a/tools/testing/selftests/x86/fsgsbase.c b/tools/testing/selftests/x86/fsgsbase.c
index 7161cfc2e60b..8c780cce941d 100644
--- a/tools/testing/selftests/x86/fsgsbase.c
+++ b/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",
diff --git a/tools/testing/selftests/x86/raw_syscall_helper_32.S b/tools/testing/selftests/x86/raw_syscall_helper_32.S
index 94410fa2b5ed..a10d36afdca0 100644
--- a/tools/testing/selftests/x86/raw_syscall_helper_32.S
+++ b/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
diff --git a/tools/testing/selftests/x86/thunks.S b/tools/testing/selftests/x86/thunks.S
index 1bb5d62c16a4..a2d47d8344d4 100644
--- a/tools/testing/selftests/x86/thunks.S
+++ b/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