[PATCH v12 59/77] KVM: introspection: restore the state of CR3 interception on unhook
From: Adalbert Lazăr <hidden>
Date: 2021-10-06 17:42:30
Also in:
kvm
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Nicușor Cîțu <redacted> This commit also ensures that the introspection tool and the userspace do not disable each other the CR3-write VM-exit. Signed-off-by: Nicușor Cîțu <redacted> Signed-off-by: Adalbert Lazăr <redacted> --- arch/x86/include/asm/kvmi_host.h | 4 ++ arch/x86/kvm/kvmi.c | 68 +++++++++++++++++++++++++++++--- arch/x86/kvm/kvmi.h | 4 +- arch/x86/kvm/kvmi_msg.c | 4 +- arch/x86/kvm/svm/svm.c | 5 +++ arch/x86/kvm/vmx/vmx.c | 5 +++ 6 files changed, 81 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/kvmi_host.h b/arch/x86/include/asm/kvmi_host.h
index 7613088d0ae2..edbedf031467 100644
--- a/arch/x86/include/asm/kvmi_host.h
+++ b/arch/x86/include/asm/kvmi_host.h@@ -16,6 +16,7 @@ struct kvmi_interception { bool cleanup; bool restore_interception; struct kvmi_monitor_interception breakpoint; + struct kvmi_monitor_interception cr3w; }; struct kvm_vcpu_arch_introspection {
@@ -34,6 +35,7 @@ bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg); bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, unsigned long old_value, unsigned long *new_value); bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu); +bool kvmi_monitor_cr3w_intercept(struct kvm_vcpu *vcpu, bool enable); #else /* CONFIG_KVM_INTROSPECTION */
@@ -44,6 +46,8 @@ static inline bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, unsigned long *new_value) { return true; } static inline bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu) { return false; } +static inline bool kvmi_monitor_cr3w_intercept(struct kvm_vcpu *vcpu, + bool enable) { return false; } #endif /* CONFIG_KVM_INTROSPECTION */
diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c
index 31a11c7120c5..acd655ab770d 100644
--- a/arch/x86/kvm/kvmi.c
+++ b/arch/x86/kvm/kvmi.c@@ -230,6 +230,59 @@ static void kvmi_arch_disable_bp_intercept(struct kvm_vcpu *vcpu) vcpu->arch.kvmi->breakpoint.kvm_intercepted = false; } +static bool monitor_cr3w_fct_kvmi(struct kvm_vcpu *vcpu, bool enable) +{ + vcpu->arch.kvmi->cr3w.kvmi_intercepted = enable; + + if (enable) + vcpu->arch.kvmi->cr3w.kvm_intercepted = + static_call(kvm_x86_cr3_write_intercepted)(vcpu); + else if (vcpu->arch.kvmi->cr3w.kvm_intercepted) + return true; + + return false; +} + +static bool monitor_cr3w_fct_kvm(struct kvm_vcpu *vcpu, bool enable) +{ + if (!vcpu->arch.kvmi->cr3w.kvmi_intercepted) + return false; + + vcpu->arch.kvmi->cr3w.kvm_intercepted = enable; + + if (!enable) + return true; + + return false; +} + +/* + * Returns true if one side (kvm or kvmi) tries to disable the CR3 write + * interception while the other side is still tracking it. + */ +bool kvmi_monitor_cr3w_intercept(struct kvm_vcpu *vcpu, bool enable) +{ + struct kvmi_interception *arch_vcpui = READ_ONCE(vcpu->arch.kvmi); + + return (arch_vcpui && arch_vcpui->cr3w.monitor_fct(vcpu, enable)); +} +EXPORT_SYMBOL(kvmi_monitor_cr3w_intercept); + +static void kvmi_control_cr3w_intercept(struct kvm_vcpu *vcpu, bool enable) +{ + vcpu->arch.kvmi->cr3w.monitor_fct = monitor_cr3w_fct_kvmi; + static_call(kvm_x86_control_cr3_intercept)(vcpu, CR_TYPE_W, enable); + vcpu->arch.kvmi->cr3w.monitor_fct = monitor_cr3w_fct_kvm; +} + +static void kvmi_arch_disable_cr3w_intercept(struct kvm_vcpu *vcpu) +{ + kvmi_control_cr3w_intercept(vcpu, false); + + vcpu->arch.kvmi->cr3w.kvmi_intercepted = false; + vcpu->arch.kvmi->cr3w.kvm_intercepted = false; +} + int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu, unsigned int event_id, bool enable) {
@@ -269,6 +322,7 @@ void kvmi_arch_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len) static void kvmi_arch_restore_interception(struct kvm_vcpu *vcpu) { kvmi_arch_disable_bp_intercept(vcpu); + kvmi_arch_disable_cr3w_intercept(vcpu); } bool kvmi_arch_clean_up_interception(struct kvm_vcpu *vcpu)
@@ -293,8 +347,13 @@ bool kvmi_arch_vcpu_alloc_interception(struct kvm_vcpu *vcpu) return false; arch_vcpui->breakpoint.monitor_fct = monitor_bp_fct_kvm; + arch_vcpui->cr3w.monitor_fct = monitor_cr3w_fct_kvm; - /* pair with kvmi_monitor_bp_intercept() */ + /* + * paired with: + * - kvmi_monitor_bp_intercept() + * - kvmi_monitor_cr3w_intercept() + */ smp_wmb(); WRITE_ONCE(vcpu->arch.kvmi, arch_vcpui);
@@ -326,8 +385,7 @@ void kvmi_arch_request_interception_cleanup(struct kvm_vcpu *vcpu, int kvmi_arch_cmd_vcpu_control_cr(struct kvm_vcpu *vcpu, int cr, bool enable) { if (cr == 3) - static_call(kvm_x86_control_cr3_intercept)(vcpu, CR_TYPE_W, - enable); + kvmi_control_cr3w_intercept(vcpu, enable); if (enable) set_bit(cr, VCPUI(vcpu)->arch.cr_mask);
@@ -347,8 +405,8 @@ static bool __kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, if (!test_bit(cr, VCPUI(vcpu)->arch.cr_mask)) return true; - action = kvmi_msg_send_cr(vcpu, cr, old_value, *new_value, - &reply_value); + action = kvmi_msg_send_vcpu_cr(vcpu, cr, old_value, *new_value, + &reply_value); switch (action) { case KVMI_EVENT_ACTION_CONTINUE: *new_value = reply_value;
diff --git a/arch/x86/kvm/kvmi.h b/arch/x86/kvm/kvmi.h
index 6f4aaebb67f9..6a444428b831 100644
--- a/arch/x86/kvm/kvmi.h
+++ b/arch/x86/kvm/kvmi.h@@ -9,7 +9,7 @@ void kvmi_arch_cmd_vcpu_set_registers(struct kvm_vcpu *vcpu, const struct kvm_regs *regs); int kvmi_arch_cmd_vcpu_control_cr(struct kvm_vcpu *vcpu, int cr, bool enable); -u32 kvmi_msg_send_cr(struct kvm_vcpu *vcpu, u32 cr, u64 old_value, - u64 new_value, u64 *ret_value); +u32 kvmi_msg_send_vcpu_cr(struct kvm_vcpu *vcpu, u32 cr, u64 old_value, + u64 new_value, u64 *ret_value); #endif
diff --git a/arch/x86/kvm/kvmi_msg.c b/arch/x86/kvm/kvmi_msg.c
index 200d68febc84..4a2dbc38aef8 100644
--- a/arch/x86/kvm/kvmi_msg.c
+++ b/arch/x86/kvm/kvmi_msg.c@@ -166,8 +166,8 @@ kvmi_vcpu_msg_job_fct kvmi_arch_vcpu_msg_handler(u16 id) return id < ARRAY_SIZE(msg_vcpu) ? msg_vcpu[id] : NULL; } -u32 kvmi_msg_send_cr(struct kvm_vcpu *vcpu, u32 cr, u64 old_value, - u64 new_value, u64 *ret_value) +u32 kvmi_msg_send_vcpu_cr(struct kvm_vcpu *vcpu, u32 cr, u64 old_value, + u64 new_value, u64 *ret_value) { struct kvmi_vcpu_event_cr e; struct kvmi_vcpu_event_cr_reply r;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 84f4f59ba703..7353996907d3 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c@@ -1935,6 +1935,11 @@ static void svm_control_cr3_intercept(struct kvm_vcpu *vcpu, int type, { struct vcpu_svm *svm = to_svm(vcpu); +#ifdef CONFIG_KVM_INTROSPECTION + if ((type & CR_TYPE_W) && kvmi_monitor_cr3w_intercept(vcpu, enable)) + type &= ~CR_TYPE_W; +#endif /* CONFIG_KVM_INTROSPECTION */ + if (type & CR_TYPE_R) enable ? svm_set_intercept(svm, INTERCEPT_CR3_READ) : svm_clr_intercept(svm, INTERCEPT_CR3_READ);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2a838595ba0b..c268194cee84 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c@@ -3011,6 +3011,11 @@ static void vmx_control_cr3_intercept(struct kvm_vcpu *vcpu, int type, struct vcpu_vmx *vmx = to_vmx(vcpu); u32 cr3_exec_control = 0; +#ifdef CONFIG_KVM_INTROSPECTION + if ((type & CR_TYPE_W) && kvmi_monitor_cr3w_intercept(vcpu, enable)) + type &= ~CR_TYPE_W; +#endif /* CONFIG_KVM_INTROSPECTION */ + if (type & CR_TYPE_R) cr3_exec_control |= CPU_BASED_CR3_STORE_EXITING; if (type & CR_TYPE_W)
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