fix: KVM: x86: Unexport kvm_x86_ops (v5.18)

See upstream commit :

  commit dfc4e6ca041135217c07ebcd102b6694cea22856
  Author: Sean Christopherson <seanjc@google.com>
  Date:   Fri Jan 28 00:51:56 2022 +0000

    KVM: x86: Unexport kvm_x86_ops

    Drop the export of kvm_x86_ops now it is no longer referenced by SVM or
    VMX.  Disallowing access to kvm_x86_ops is very desirable as it prevents
    vendor code from incorrectly modifying hooks after they have been set by
    kvm_arch_hardware_setup(), and more importantly after each function's
    associated static_call key has been updated.

    No functional change intended.

Change-Id: Icee959a984570f95ab9b71354225b5aeecea7da0
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/include/instrumentation/events/arch/x86/kvm/trace.h b/include/instrumentation/events/arch/x86/kvm/trace.h
index 42e5b94d82e6fba95aa1a3c6b16ef8b5d2dd023f..0d6c4e3319361e4c9823e0d18da36ff148d0fdac 100644 (file)
--- a/include/instrumentation/events/arch/x86/kvm/trace.h
+++ b/include/instrumentation/events/arch/x86/kvm/trace.h
@@ -9,6 +9,7 @@
 #include <asm/clocksource.h>
 #endif
 #include <lttng/kernel-version.h>
+#include <wrapper/kvm-x86.h>
 #include <../arch/x86/kvm/lapic.h>
 #include <../arch/x86/kvm/kvm_cache_regs.h>
 
@@ -115,7 +116,40 @@ LTTNG_TRACEPOINT_EVENT_MAP(kvm_apic, kvm_x86_apic,
 /*
  * Tracepoint for kvm guest exit:
  */
-#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,16,0))
+#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0))
+LTTNG_TRACEPOINT_EVENT_CODE_MAP(kvm_exit, kvm_x86_exit,
+       TP_PROTO(struct kvm_vcpu *vcpu, u32 isa),
+       TP_ARGS(vcpu, isa),
+
+       TP_locvar(
+               u32 exit_reason;
+               u64 info1, info2;
+               u32 intr_info, error_code;
+       ),
+
+       TP_code_pre(
+               lttng_kvm_x86_get_exit_info(vcpu,
+                               &tp_locvar->exit_reason,
+                               &tp_locvar->info1,
+                               &tp_locvar->info2,
+                               &tp_locvar->intr_info,
+                               &tp_locvar->error_code);
+       ),
+
+       TP_FIELDS(
+               ctf_integer(unsigned int, exit_reason, tp_locvar->exit_reason)
+               ctf_integer(unsigned long, guest_rip, kvm_rip_read(vcpu))
+               ctf_integer(u32, isa, isa)
+               ctf_integer(u64, info1, tp_locvar->info1)
+               ctf_integer(u64, info2, tp_locvar->info2)
+               ctf_integer(u32, intr_info, tp_locvar->intr_info)
+               ctf_integer(u32, error_code, tp_locvar->error_code)
+               ctf_integer(unsigned int, vcpu_id, vcpu->vcpu_id)
+       ),
+
+       TP_code_post()
+)
+#elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,16,0))
 LTTNG_TRACEPOINT_EVENT_CODE_MAP(kvm_exit, kvm_x86_exit,
        TP_PROTO(struct kvm_vcpu *vcpu, u32 isa),
        TP_ARGS(vcpu, isa),
@@ -535,7 +569,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(kvm_emulate_insn, kvm_x86_emulate_insn,
                                vcpu->arch.emulate_ctxt.fetch.data)
                ctf_array(__u8, insn, vcpu->arch.emulate_ctxt.fetch.data, 15)
                ctf_integer(__u8, flags, kei_decode_mode(vcpu->arch.emulate_ctxt.mode))
-#else
+#elif (LTTNG_LINUX_VERSION_CODE < LTTNG_KERNEL_VERSION(5,18,0))
                ctf_integer(__u64, rip, vcpu->arch.emulate_ctxt->_eip -
                                (vcpu->arch.emulate_ctxt->fetch.ptr -
                                        vcpu->arch.emulate_ctxt->fetch.data))
@@ -544,6 +578,15 @@ LTTNG_TRACEPOINT_EVENT_MAP(kvm_emulate_insn, kvm_x86_emulate_insn,
                                vcpu->arch.emulate_ctxt->fetch.data)
                ctf_array(__u8, insn, vcpu->arch.emulate_ctxt->fetch.data, 15)
                ctf_integer(__u8, flags, kei_decode_mode(vcpu->arch.emulate_ctxt->mode))
+#else
+               ctf_integer(__u64, rip, vcpu->arch.emulate_ctxt->_eip -
+                               (vcpu->arch.emulate_ctxt->fetch.ptr -
+                                       vcpu->arch.emulate_ctxt->fetch.data))
+               ctf_integer(__u32, csbase, lttng_kvm_x86_get_segment_base(vcpu, VCPU_SREG_CS))
+               ctf_integer(__u8, len, vcpu->arch.emulate_ctxt->fetch.ptr -
+                               vcpu->arch.emulate_ctxt->fetch.data)
+               ctf_array(__u8, insn, vcpu->arch.emulate_ctxt->fetch.data, 15)
+               ctf_integer(__u8, flags, kei_decode_mode(vcpu->arch.emulate_ctxt->mode))
 #endif
                ctf_integer(__u8, failed, failed)
        )

diff --git a/include/wrapper/kvm-x86.h b/include/wrapper/kvm-x86.h
new file mode 100644 (file)
index 0000000..2007aeb
--- /dev/null
+++ b/include/wrapper/kvm-x86.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
+ *
+ * wrapper/kvm-x86.h
+ *
+ * Copyright (C) 2022 Michael Jeanson <mjeanson@efficios.com>
+ */
+
+#ifndef _LTTNG_WRAPPER_KVM_X86_H
+#define _LTTNG_WRAPPER_KVM_X86_H
+
+#include <linux/kvm_host.h>
+#include <lttng/kernel-version.h>
+
+#if LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0)
+
+#ifdef CONFIG_KALLSYMS_ALL
+#include <linux/kallsyms.h>
+#include <wrapper/kallsyms.h>
+
+static struct kvm_x86_ops *kvm_x86_ops_sym;
+
+static inline
+void lttng_kvm_x86_get_exit_info(
+               struct kvm_vcpu *vcpu, u32 *reason,
+               u64 *info1, u64 *info2,
+               u32 *exit_int_info, u32 *exit_int_info_err_code)
+{
+       if (!kvm_x86_ops_sym)
+               kvm_x86_ops_sym =
+                       (void *) kallsyms_lookup_dataptr("kvm_x86_ops");
+
+       if (kvm_x86_ops_sym) {
+               kvm_x86_ops_sym->get_exit_info(vcpu, reason, info1, info2,
+                               exit_int_info, exit_int_info_err_code);
+       } else {
+               printk_once(KERN_WARNING "LTTng: kvm_x86_ops symbol lookup failed.\n");
+       }
+}
+
+static inline
+u64 lttng_kvm_x86_get_segment_base(struct kvm_vcpu *vcpu, int seg)
+{
+       if (!kvm_x86_ops_sym)
+               kvm_x86_ops_sym =
+                       (void *) kallsyms_lookup_dataptr("kvm_x86_ops");
+
+       if (kvm_x86_ops_sym) {
+               return kvm_x86_ops_sym->get_segment_base(vcpu, seg);
+       } else {
+               printk_once(KERN_WARNING "LTTng: kvm_x86_ops symbol lookup failed.\n");
+               return 0;
+       }
+}
+
+/*
+ * Canary function to check for 'kvm_x86_ops' at compile time.
+ *
+ * From 'arch/x86/include/asm/kvm_host.h':
+ *
+ *   extern struct kvm_x86_ops kvm_x86_ops;;
+ */
+static inline
+unsigned int __canary__kvm_x86_ops(void)
+{
+       return kvm_x86_ops.vm_size;
+}
+
+#endif /* CONFIG_KALLSYMS_ALL */
+
+#endif
+
+#endif /* _LTTNG_WRAPPER_KVM_X86_H */