Merge tag 'kvm-x86-misc-6.7' of https://github.com/kvm-x86/linux into HEAD

KVM x86 misc changes for 6.7:

 - Add CONFIG_KVM_MAX_NR_VCPUS to allow supporting up to 4096 vCPUs without
   forcing more common use cases to eat the extra memory overhead.

 - Add IBPB and SBPB virtualization support.

 - Fix a bug where restoring a vCPU snapshot that was taken within 1 second of
   creating the original vCPU would cause KVM to try to synchronize the vCPU's
   TSC and thus clobber the correct TSC being set by userspace.

 - Compute guest wall clock using a single TSC read to avoid generating an
   inaccurate time, e.g. if the vCPU is preempted between multiple TSC reads.

 - "Virtualize" HWCR.TscFreqSel to make Linux guests happy, which complain
    about a "Firmware Bug" if the bit isn't set for select F/M/S combos.

 - Don't apply side effects to Hyper-V's synthetic timer on writes from
   userspace to fix an issue where the auto-enable behavior can trigger
   spurious interrupts, i.e. do auto-enabling only for guest writes.

 - Remove an unnecessary kick of all vCPUs when synchronizing the dirty log
   without PML enabled.

 - Advertise "support" for non-serializing FS/GS base MSR writes as appropriate.

 - Use octal notation for file permissions through KVM x86.

 - Fix a handful of typo fixes and warts.

2 files changed, 48 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index a3bb36fb3cfc55..fb01c3f8d3da2a 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -66,6 +66,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/dirty_log_page_splitting_test
 TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features
 TEST_GEN_PROGS_x86_64 += x86_64/exit_on_emulation_failure_test
 TEST_GEN_PROGS_x86_64 += x86_64/fix_hypercall_test
+TEST_GEN_PROGS_x86_64 += x86_64/hwcr_msr_test
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_evmcs
diff --git a/tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c b/tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c
new file mode 100644
index 00000000000000..df351ae1702977
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/hwcr_msr_test.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023, Google LLC.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "vmx.h"
+
+void test_hwcr_bit(struct kvm_vcpu *vcpu, unsigned int bit)
+{
+	const uint64_t ignored = BIT_ULL(3) | BIT_ULL(6) | BIT_ULL(8);
+	const uint64_t valid = BIT_ULL(18) | BIT_ULL(24);
+	const uint64_t legal = ignored | valid;
+	uint64_t val = BIT_ULL(bit);
+	uint64_t actual;
+	int r;
+
+	r = _vcpu_set_msr(vcpu, MSR_K7_HWCR, val);
+	TEST_ASSERT(val & ~legal ? !r : r == 1,
+		    "Expected KVM_SET_MSRS(MSR_K7_HWCR) = 0x%lx to %s",
+		    val, val & ~legal ? "fail" : "succeed");
+
+	actual = vcpu_get_msr(vcpu, MSR_K7_HWCR);
+	TEST_ASSERT(actual == (val & valid),
+		    "Bit %u: unexpected HWCR 0x%lx; expected 0x%lx",
+		    bit, actual, (val & valid));
+
+	vcpu_set_msr(vcpu, MSR_K7_HWCR, 0);
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	unsigned int bit;
+
+	vm = vm_create_with_one_vcpu(&vcpu, NULL);
+
+	for (bit = 0; bit < BITS_PER_LONG; bit++)
+		test_hwcr_bit(vcpu, bit);
+
+	kvm_vm_free(vm);
+}