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[PATCH v14 22/22] KVM: selftest: Add tests for KVM_{GET,SET}_ONE_REG

Chao Gao posted 22 patches 3 weeks, 2 days ago
[PATCH v14 22/22] KVM: selftest: Add tests for KVM_{GET,SET}_ONE_REG
Posted by Chao Gao 3 weeks, 2 days ago 
Add tests for newly added KVM_{GET,SET}_ONE_REG support for x86. Verify the
new ioctls can read and write real MSRs and synthetic MSRs.

Signed-off-by: Chao Gao <chao.gao@intel.com>
---
 tools/arch/x86/include/uapi/asm/kvm.h         | 29 ++++++++++++++++++
 tools/testing/selftests/kvm/Makefile.kvm      |  1 +
 .../selftests/kvm/x86/get_set_one_reg.c       | 30 +++++++++++++++++++
 3 files changed, 60 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86/get_set_one_reg.c

diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
index 6f3499507c5e..59ac0b46ebcc 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -411,6 +411,35 @@ struct kvm_xcrs {
 	__u64 padding[16];
 };
 
+#define KVM_X86_REG_TYPE_MSR		2
+#define KVM_X86_REG_TYPE_KVM		3
+
+#define KVM_X86_KVM_REG_SIZE(reg)						\
+({										\
+	reg == KVM_REG_GUEST_SSP ? KVM_REG_SIZE_U64 : 0;			\
+})
+
+#define KVM_X86_REG_TYPE_SIZE(type, reg)					\
+({										\
+	__u64 type_size = (__u64)type << 32;					\
+										\
+	type_size |= type == KVM_X86_REG_TYPE_MSR ? KVM_REG_SIZE_U64 :		\
+		     type == KVM_X86_REG_TYPE_KVM ? KVM_X86_KVM_REG_SIZE(reg) :	\
+		     0;								\
+	type_size;								\
+})
+
+#define KVM_X86_REG_ENCODE(type, index)				\
+	(KVM_REG_X86 | KVM_X86_REG_TYPE_SIZE(type, index) | index)
+
+#define KVM_X86_REG_MSR(index)					\
+	KVM_X86_REG_ENCODE(KVM_X86_REG_TYPE_MSR, index)
+#define KVM_X86_REG_KVM(index)					\
+	KVM_X86_REG_ENCODE(KVM_X86_REG_TYPE_KVM, index)
+
+/* KVM-defined registers starting from 0 */
+#define KVM_REG_GUEST_SSP	0
+
 #define KVM_SYNC_X86_REGS      (1UL << 0)
 #define KVM_SYNC_X86_SREGS     (1UL << 1)
 #define KVM_SYNC_X86_EVENTS    (1UL << 2)
diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index f6fe7a07a0a2..9a375d5faf1c 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -136,6 +136,7 @@ TEST_GEN_PROGS_x86 += x86/max_vcpuid_cap_test
 TEST_GEN_PROGS_x86 += x86/triple_fault_event_test
 TEST_GEN_PROGS_x86 += x86/recalc_apic_map_test
 TEST_GEN_PROGS_x86 += x86/aperfmperf_test
+TEST_GEN_PROGS_x86 += x86/get_set_one_reg
 TEST_GEN_PROGS_x86 += access_tracking_perf_test
 TEST_GEN_PROGS_x86 += coalesced_io_test
 TEST_GEN_PROGS_x86 += dirty_log_perf_test
diff --git a/tools/testing/selftests/kvm/x86/get_set_one_reg.c b/tools/testing/selftests/kvm/x86/get_set_one_reg.c
new file mode 100644
index 000000000000..8a4dbc812214
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86/get_set_one_reg.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <fcntl.h>
+#include <stdint.h>
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	u64 data;
+
+	TEST_REQUIRE(kvm_has_cap(KVM_CAP_ONE_REG));
+
+	vm = vm_create_with_one_vcpu(&vcpu, NULL);
+
+	TEST_ASSERT_EQ(__vcpu_get_reg(vcpu, KVM_X86_REG_MSR(MSR_EFER), &data), 0);
+	TEST_ASSERT_EQ(__vcpu_set_reg(vcpu, KVM_X86_REG_MSR(MSR_EFER), data), 0);
+
+	if (kvm_cpu_has(X86_FEATURE_SHSTK)) {
+		TEST_ASSERT_EQ(__vcpu_get_reg(vcpu, KVM_X86_REG_KVM(KVM_REG_GUEST_SSP), &data), 0);
+		TEST_ASSERT_EQ(__vcpu_set_reg(vcpu, KVM_X86_REG_KVM(KVM_REG_GUEST_SSP), data), 0);
+	}
+
+	kvm_vm_free(vm);
+	return 0;
+}
-- 
2.47.3
Re: [PATCH v14 22/22] KVM: selftest: Add tests for KVM_{GET,SET}_ONE_REG
Posted by Sean Christopherson 3 weeks, 1 day ago 
On Tue, Sep 09, 2025, Chao Gao wrote:
> Add tests for newly added KVM_{GET,SET}_ONE_REG support for x86. Verify the
> new ioctls can read and write real MSRs and synthetic MSRs.
> 
> Signed-off-by: Chao Gao <chao.gao@intel.com>
> ---
>  tools/arch/x86/include/uapi/asm/kvm.h         | 29 ++++++++++++++++++
>  tools/testing/selftests/kvm/Makefile.kvm      |  1 +
>  .../selftests/kvm/x86/get_set_one_reg.c       | 30 +++++++++++++++++++
>  3 files changed, 60 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/x86/get_set_one_reg.c
> 
> diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
> index 6f3499507c5e..59ac0b46ebcc 100644
> --- a/tools/arch/x86/include/uapi/asm/kvm.h
> +++ b/tools/arch/x86/include/uapi/asm/kvm.h

Don't copy KVM headers to tools/, KVM selftests don't actually use them (i.e.
copying them is confusing/misleadling).  The copied headers are mainly used by
tools/perf, and they run a script to synchronize everything.

> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> index f6fe7a07a0a2..9a375d5faf1c 100644
> --- a/tools/testing/selftests/kvm/Makefile.kvm
> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> @@ -136,6 +136,7 @@ TEST_GEN_PROGS_x86 += x86/max_vcpuid_cap_test
>  TEST_GEN_PROGS_x86 += x86/triple_fault_event_test
>  TEST_GEN_PROGS_x86 += x86/recalc_apic_map_test
>  TEST_GEN_PROGS_x86 += x86/aperfmperf_test
> +TEST_GEN_PROGS_x86 += x86/get_set_one_reg
>  TEST_GEN_PROGS_x86 += access_tracking_perf_test
>  TEST_GEN_PROGS_x86 += coalesced_io_test
>  TEST_GEN_PROGS_x86 += dirty_log_perf_test
> diff --git a/tools/testing/selftests/kvm/x86/get_set_one_reg.c b/tools/testing/selftests/kvm/x86/get_set_one_reg.c
> new file mode 100644
> index 000000000000..8a4dbc812214
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86/get_set_one_reg.c
> @@ -0,0 +1,30 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <fcntl.h>
> +#include <stdint.h>
> +#include <sys/ioctl.h>
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +#include "processor.h"
> +
> +int main(int argc, char *argv[])
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +	u64 data;
> +
> +	TEST_REQUIRE(kvm_has_cap(KVM_CAP_ONE_REG));
> +
> +	vm = vm_create_with_one_vcpu(&vcpu, NULL);
> +
> +	TEST_ASSERT_EQ(__vcpu_get_reg(vcpu, KVM_X86_REG_MSR(MSR_EFER), &data), 0);
> +	TEST_ASSERT_EQ(__vcpu_set_reg(vcpu, KVM_X86_REG_MSR(MSR_EFER), data), 0);
> +
> +	if (kvm_cpu_has(X86_FEATURE_SHSTK)) {
> +		TEST_ASSERT_EQ(__vcpu_get_reg(vcpu, KVM_X86_REG_KVM(KVM_REG_GUEST_SSP), &data), 0);
> +		TEST_ASSERT_EQ(__vcpu_set_reg(vcpu, KVM_X86_REG_KVM(KVM_REG_GUEST_SSP), data), 0);

This isn't a very useful test, nor is it extensible.  I finally bit the bullet
and created an MSR test to mostly replace KUT's msr.c, and to add coverage for
KVM_{G,S}ET_ONE_REG and KVM_GET_REG_LIST.

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