KVM: selftests: Test behavior of HWCR, a.k.a. MSR_K7_HWCR

Verify the following behavior holds true for writes and reads of HWCR from
host userspace:

* Attempts to set bits 3, 6, or 8 are ignored
* Bits 18 and 24 are the only bits that can be set
* Any bit that can be set can also be cleared

Signed-off-by: Jim Mattson <jmattson@google.com>
Link: https://lore.kernel.org/r/20230929230246.1954854-4-jmattson@google.com
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index a3bb36fb3cfc55a423d31c10e86c1fe16b79ca0e..fb01c3f8d3da2a26c515ab8a1c3d0a86b54d0032 100644 (file)
--- 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 (file)
index 0000000..df351ae
--- /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);
+}