Merge remote-tracking branch 'kvm/queue' into HEAD

x86 Xen-for-KVM:

* Allow the Xen runstate information to cross a page boundary

* Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured

* add support for 32-bit guests in SCHEDOP_poll

x86 fixes:

* One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).

* Reinstate IBPB on emulated VM-Exit that was incorrectly dropped a few
   years back when eliminating unnecessary barriers when switching between
   vmcs01 and vmcs02.

* Clean up the MSR filter docs.

* Clean up vmread_error_trampoline() to make it more obvious that params
  must be passed on the stack, even for x86-64.

* Let userspace set all supported bits in MSR_IA32_FEAT_CTL irrespective
  of the current guest CPUID.

* Fudge around a race with TSC refinement that results in KVM incorrectly
  thinking a guest needs TSC scaling when running on a CPU with a
  constant TSC, but no hardware-enumerated TSC frequency.

* Advertise (on AMD) that the SMM_CTL MSR is not supported

* Remove unnecessary exports

Selftests:

* Fix an inverted check in the access tracking perf test, and restore
  support for asserting that there aren't too many idle pages when
  running on bare metal.

* Fix an ordering issue in the AMX test introduced by recent conversions
  to use kvm_cpu_has(), and harden the code to guard against similar bugs
  in the future.  Anything that tiggers caching of KVM's supported CPUID,
  kvm_cpu_has() in this case, effectively hides opt-in XSAVE features if
  the caching occurs before the test opts in via prctl().

* Fix build errors that occur in certain setups (unsure exactly what is
  unique about the problematic setup) due to glibc overriding
  static_assert() to a variant that requires a custom message.

* Introduce actual atomics for clear/set_bit() in selftests

Documentation:

* Remove deleted ioctls from documentation

* Various fixes

1 files changed, 11 insertions, 10 deletions

diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
index 8a3fb212084a..637be796086f 100644
--- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
+++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
@@ -375,10 +375,6 @@ static void guest_svc_handler(struct ex_regs *regs)
 	svc_addr = regs->pc;
 }
 
-enum single_step_op {
-	SINGLE_STEP_ENABLE = 0,
-};
-
 static void guest_code_ss(int test_cnt)
 {
 	uint64_t i;
@@ -389,8 +385,16 @@ static void guest_code_ss(int test_cnt)
 		w_bvr = i << 2;
 		w_wvr = i << 2;
 
-		/* Enable Single Step execution */
-		GUEST_SYNC(SINGLE_STEP_ENABLE);
+		/*
+		 * Enable Single Step execution.  Note!  This _must_ be a bare
+		 * ucall as the ucall() path uses atomic operations to manage
+		 * the ucall structures, and the built-in "atomics" are usually
+		 * implemented via exclusive access instructions.  The exlusive
+		 * monitor is cleared on ERET, and so taking debug exceptions
+		 * during a LDREX=>STREX sequence will prevent forward progress
+		 * and hang the guest/test.
+		 */
+		GUEST_UCALL_NONE();
 
 		/*
 		 * The userspace will verify that the pc is as expected during
@@ -484,12 +488,9 @@ void test_single_step_from_userspace(int test_cnt)
 				break;
 			}
 
-			TEST_ASSERT(cmd == UCALL_SYNC,
+			TEST_ASSERT(cmd == UCALL_NONE,
 				    "Unexpected ucall cmd 0x%lx", cmd);
 
-			TEST_ASSERT(uc.args[1] == SINGLE_STEP_ENABLE,
-				    "Unexpected ucall action 0x%lx", uc.args[1]);
-
 			debug.control = KVM_GUESTDBG_ENABLE |
 					KVM_GUESTDBG_SINGLESTEP;
 			ss_enable = true;