[RFC,v7,73/78] KVM: introspection: extend KVMI_GET_VERSION with struct kvmi_features

Commit Message

Adalbert Lazăr Feb. 7, 2020, 6:16 p.m. UTC

This is used by the introspection tool to check the hardware support
for single step.

Signed-off-by: Adalbert Lazăr <[e-mail]>
---
 Documentation/virt/kvm/kvmi.rst                | 13 ++++++++++++-
 arch/x86/include/uapi/asm/kvmi.h               |  5 +++++
 arch/x86/kvm/kvmi.c                            |  5 +++++
 include/uapi/linux/kvmi.h                      |  1 +
 tools/testing/selftests/kvm/x86_64/kvmi_test.c |  5 +++++
 virt/kvm/introspection/kvmi_int.h              |  1 +
 virt/kvm/introspection/kvmi_msg.c              |  2 ++
 7 files changed, 31 insertions(+), 1 deletion(-)

Patch

diff --git a/Documentation/virt/kvm/kvmi.rst b/Documentation/virt/kvm/kvmi.rst
index 7994d6e8cacf..454d7ae75ae6 100644
--- a/Documentation/virt/kvm/kvmi.rst
+++ b/Documentation/virt/kvm/kvmi.rst
@@ -254,9 +254,20 @@  The commands related to vCPUs start with::
 	struct kvmi_get_version_reply {
 		__u32 version;
 		__u32 padding;
+		struct kvmi_features features;
 	};
 
-Returns the introspection API version.
+For x86
+
+::
+
+	struct kvmi_features {
+		__u8 singlestep;
+		__u8 padding[7];
+	};
+
+Returns the introspection API version and some of the features supported
+by the hardware.
 
 This command is always allowed and successful (if the introspection is
 built in kernel).
diff --git a/arch/x86/include/uapi/asm/kvmi.h b/arch/x86/include/uapi/asm/kvmi.h
index f4be7d12f63a..8e2056ad11a7 100644
--- a/arch/x86/include/uapi/asm/kvmi.h
+++ b/arch/x86/include/uapi/asm/kvmi.h
@@ -139,4 +139,9 @@  struct kvmi_event_msr_reply {
 	__u64 new_val;
 };
 
+struct kvmi_features {
+	__u8 singlestep;
+	__u8 padding[7];
+};
+
 #endif /* _UAPI_ASM_X86_KVMI_H */
diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c
index 4e8b8e0a2961..5cf266d13375 100644
--- a/arch/x86/kvm/kvmi.c
+++ b/arch/x86/kvm/kvmi.c
@@ -1100,6 +1100,11 @@  bool kvmi_arch_pf_event(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva,
 	return ret;
 }
 
+void kvmi_arch_features(struct kvmi_features *feat)
+{
+	feat->singlestep = !!kvm_x86_ops->control_singlestep;
+}
+
 bool kvmi_arch_pf_of_interest(struct kvm_vcpu *vcpu)
 {
 	return kvm_x86_ops->spt_fault(vcpu) &&
diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h
index c74ded097efa..7cd41a815967 100644
--- a/include/uapi/linux/kvmi.h
+++ b/include/uapi/linux/kvmi.h
@@ -91,6 +91,7 @@  struct kvmi_error_code {
 struct kvmi_get_version_reply {
 	__u32 version;
 	__u32 padding;
+	struct kvmi_features features;
 };
 
 struct kvmi_vm_check_command {
diff --git a/tools/testing/selftests/kvm/x86_64/kvmi_test.c b/tools/testing/selftests/kvm/x86_64/kvmi_test.c
index e8d3ccac1caa..a27588c27eb8 100644
--- a/tools/testing/selftests/kvm/x86_64/kvmi_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvmi_test.c
@@ -55,6 +55,8 @@  struct vcpu_worker_data {
 	bool restart_on_shutdown;
 };
 
+static struct kvmi_features features;
+
 typedef void (*fct_pf_event)(struct kvm_vm *vm, struct kvmi_msg_hdr *hdr,
 				struct pf_ev *ev,
 				struct vcpu_reply *rpl);
@@ -371,7 +373,10 @@  static void test_cmd_get_version(void)
 		    "Unexpected KVMI version %d, expecting %d\n",
 		    rpl.version, KVMI_VERSION);
 
+	features = rpl.features;
+
 	DEBUG("KVMI version: %u\n", rpl.version);
+	DEBUG("\tsinglestep: %u\n", features.singlestep);
 }
 
 static int cmd_check_command(__u16 id)
diff --git a/virt/kvm/introspection/kvmi_int.h b/virt/kvm/introspection/kvmi_int.h
index 23a088afe072..06b924277f37 100644
--- a/virt/kvm/introspection/kvmi_int.h
+++ b/virt/kvm/introspection/kvmi_int.h
@@ -167,5 +167,6 @@  int kvmi_arch_cmd_set_page_access(struct kvm_introspection *kvmi,
 bool kvmi_arch_pf_event(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva,
 			u8 access);
 bool kvmi_arch_pf_of_interest(struct kvm_vcpu *vcpu);
+void kvmi_arch_features(struct kvmi_features *feat);
 
 #endif
diff --git a/virt/kvm/introspection/kvmi_msg.c b/virt/kvm/introspection/kvmi_msg.c
index 49f49f2401bc..8c7cdbd96faa 100644
--- a/virt/kvm/introspection/kvmi_msg.c
+++ b/virt/kvm/introspection/kvmi_msg.c
@@ -184,6 +184,8 @@  static int handle_get_version(struct kvm_introspection *kvmi,
 	memset(&rpl, 0, sizeof(rpl));
 	rpl.version = KVMI_VERSION;
 
+	kvmi_arch_features(&rpl.features);
+
 	return kvmi_msg_vm_reply(kvmi, msg, 0, &rpl, sizeof(rpl));
 }