From: Aaron Lewis <aaronlewis@xxxxxxxxxx>
Check both architectural rules and KVM's ABI for KVM_GET_SUPPORTED_CPUID
to ensure the supported xfeatures[1] don't violate any of them.
The architectural rules[2] and KVM's contract with userspace ensure for a
given feature, e.g. sse, avx, amx, etc... their associated xfeatures are
either all sets or none of them are set, and any dependencies are enabled
if needed.
[1] EDX:EAX of CPUID.(EAX=0DH,ECX=0)
[2] SDM vol 1, 13.3 ENABLING THE XSAVE FEATURE SET AND XSAVE-ENABLED
FEATURES
Cc: Mingwei Zhang <mizhang@xxxxxxxxxx>
Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx>
[sean: expand comments, use a fancy X86_PROPERTY]
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/x86_64/processor.h | 20 +++
.../selftests/kvm/x86_64/xcr0_cpuid_test.c | 132 ++++++++++++++++++
3 files changed, 153 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 84a627c43795..18cadc669798 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -105,6 +105,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_nested_tsc_scaling_test
TEST_GEN_PROGS_x86_64 += x86_64/xapic_ipi_test
TEST_GEN_PROGS_x86_64 += x86_64/xapic_state_test
+TEST_GEN_PROGS_x86_64 += x86_64/xcr0_cpuid_test
TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
TEST_GEN_PROGS_x86_64 += x86_64/debug_regs
TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_test
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 187309f3e7e9..70c5469e4023 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -241,8 +241,11 @@ struct kvm_x86_cpu_property {
#define X86_PROPERTY_PMU_NR_GP_COUNTERS KVM_X86_CPU_PROPERTY(0xa, 0, EAX, 8, 15)
#define X86_PROPERTY_PMU_EBX_BIT_VECTOR_LENGTH KVM_X86_CPU_PROPERTY(0xa, 0, EAX, 24, 31)
+#define X86_PROPERTY_SUPPORTED_XCR0_LO KVM_X86_CPU_PROPERTY(0xd, 0, EAX, 0, 31)
#define X86_PROPERTY_XSTATE_MAX_SIZE_XCR0 KVM_X86_CPU_PROPERTY(0xd, 0, EBX, 0, 31)
#define X86_PROPERTY_XSTATE_MAX_SIZE KVM_X86_CPU_PROPERTY(0xd, 0, ECX, 0, 31)
+#define X86_PROPERTY_SUPPORTED_XCR0_HI KVM_X86_CPU_PROPERTY(0xd, 0, EDX, 0, 31)
+
#define X86_PROPERTY_XSTATE_TILE_SIZE KVM_X86_CPU_PROPERTY(0xd, 18, EAX, 0, 31)
#define X86_PROPERTY_XSTATE_TILE_OFFSET KVM_X86_CPU_PROPERTY(0xd, 18, EBX, 0, 31)
#define X86_PROPERTY_AMX_MAX_PALETTE_TABLES KVM_X86_CPU_PROPERTY(0x1d, 0, EAX, 0, 31)
@@ -681,6 +684,15 @@ static inline bool this_pmu_has(struct kvm_x86_pmu_feature feature)
!this_cpu_has(feature.anti_feature);
}
+static __always_inline uint64_t this_cpu_supported_xcr0(void)
+{
+ if (!this_cpu_has_p(X86_PROPERTY_SUPPORTED_XCR0_LO))
+ return 0;
+
+ return this_cpu_property(X86_PROPERTY_SUPPORTED_XCR0_LO) |
+ ((uint64_t)this_cpu_property(X86_PROPERTY_SUPPORTED_XCR0_HI) << 32);
+}
+
typedef u32 __attribute__((vector_size(16))) sse128_t;
#define __sse128_u union { sse128_t vec; u64 as_u64[2]; u32 as_u32[4]; }
#define sse128_lo(x) ({ __sse128_u t; t.vec = x; t.as_u64[0]; })
@@ -1104,6 +1116,14 @@ static inline uint8_t wrmsr_safe(uint32_t msr, uint64_t val)
return kvm_asm_safe("wrmsr", "a"(val & -1u), "d"(val >> 32), "c"(msr));
}
+static inline uint8_t xsetbv_safe(uint32_t index, uint64_t value)
+{
+ u32 eax = value;
+ u32 edx = value >> 32;
+
+ return kvm_asm_safe("xsetbv", "a" (eax), "d" (edx), "c" (index));
+}
+
bool kvm_is_tdp_enabled(void);
uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
diff --git a/tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c b/tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c
new file mode 100644
index 000000000000..905bd5ae4431
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/xcr0_cpuid_test.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * XCR0 cpuid test
+ *
+ * Copyright (C) 2022, Google LLC.
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "processor.h"
+
+/*
+ * Assert that architectural dependency rules are satisfied, e.g. that AVX is
+ * supported if and only if SSE is supported.
+ */
+#define ASSERT_XFEATURE_DEPENDENCIES(supported_xcr0, xfeatures, dependencies) \
+do { \
+ uint64_t __supported = (supported_xcr0) & ((xfeatures) | (dependencies)); \
+ \
+ GUEST_ASSERT_3((__supported & (xfeatures)) != (xfeatures) || \
+ __supported == ((xfeatures) | (dependencies)), \
+ __supported, (xfeatures), (dependencies)); \
+} while (0)
+
+/*
+ * Assert that KVM reports a sane, usable as-is XCR0. Architecturally, a CPU
+ * isn't strictly required to _support_ all XFeatures related to a feature, but
+ * at the same time XSETBV will #GP if bundled XFeatures aren't enabled and
+ * disabled coherently. E.g. a CPU can technically enumerate supported for
+ * XTILE_CFG but not XTILE_DATA, but attempting to enable XTILE_CFG without
+ * XTILE_DATA will #GP.
+ */
+#define ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0, xfeatures) \
+do { \
+ uint64_t __supported = (supported_xcr0) & (xfeatures); \
+ \
+ GUEST_ASSERT_2(!__supported || __supported == (xfeatures), \
+ __supported, (xfeatures)); \
+} while (0)
+
+static void guest_code(void)
+{
+ uint64_t xcr0_reset;
+ uint64_t supported_xcr0;
+ int i, vector;
+
+ set_cr4(get_cr4() | X86_CR4_OSXSAVE);
+
+ xcr0_reset = xgetbv(0);
+ supported_xcr0 = this_cpu_supported_xcr0();
+
+ GUEST_ASSERT(xcr0_reset == XFEATURE_MASK_FP);
+
+ /* Check AVX */
+ ASSERT_XFEATURE_DEPENDENCIES(supported_xcr0,
+ XFEATURE_MASK_YMM,
+ XFEATURE_MASK_SSE);
+
+ /* Check MPX */
+ ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0,
+ XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
+
+ /* Check AVX-512 */
+ ASSERT_XFEATURE_DEPENDENCIES(supported_xcr0,
+ XFEATURE_MASK_AVX512,
+ XFEATURE_MASK_SSE | XFEATURE_MASK_YMM);
+ ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0,
+ XFEATURE_MASK_AVX512);
+
+ /* Check AMX */
+ ASSERT_ALL_OR_NONE_XFEATURE(supported_xcr0,
+ XFEATURE_MASK_XTILE);
+
+ vector = xsetbv_safe(0, supported_xcr0);
+ GUEST_ASSERT_2(!vector, supported_xcr0, vector);
+
+ for (i = 0; i < 64; i++) {
+ if (supported_xcr0 & BIT_ULL(i))
+ continue;
+
+ vector = xsetbv_safe(0, supported_xcr0 | BIT_ULL(i));
+ GUEST_ASSERT_3(vector == GP_VECTOR, supported_xcr0, vector, BIT_ULL(i));
+ }
+
+ GUEST_DONE();
+}
+
+int main(int argc, char *argv[])
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_run *run;
+ struct kvm_vm *vm;
+ struct ucall uc;
+
+ TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_XSAVE));
+
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+ run = vcpu->run;
+
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vcpu);
+
+ while (1) {
+ vcpu_run(vcpu);
+
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Unexpected exit reason: %u (%s),\n",
+ run->exit_reason,
+ exit_reason_str(run->exit_reason));
+
+ switch (get_ucall(vcpu, &uc)) {
+ case UCALL_ABORT:
+ REPORT_GUEST_ASSERT_3(uc, "0x%lx 0x%lx 0x%lx");
+ break;
+ case UCALL_DONE:
+ goto done;
+ default:
+ TEST_FAIL("Unknown ucall %lu", uc.cmd);
+ }
+ }
+
+done:
+ kvm_vm_free(vm);
+ return 0;
+}
--
2.40.0.348.gf938b09366-goog
