From: Nicușor Cîțu <[email protected]> This commit also ensures that the introspection tool and the userspace do not disable each other the MSR access VM-exit.
Signed-off-by: Nicușor Cîțu <[email protected]> Signed-off-by: Adalbert Lazăr <[email protected]> --- arch/x86/include/asm/kvmi_host.h | 12 ++++ arch/x86/kvm/kvmi.c | 119 +++++++++++++++++++++++++++---- arch/x86/kvm/svm.c | 11 +++ arch/x86/kvm/vmx/vmx.c | 11 +++ 4 files changed, 139 insertions(+), 14 deletions(-) diff --git a/arch/x86/include/asm/kvmi_host.h b/arch/x86/include/asm/kvmi_host.h index f9aaff45d082..875778d80176 100644 --- a/arch/x86/include/asm/kvmi_host.h +++ b/arch/x86/include/asm/kvmi_host.h @@ -23,6 +23,12 @@ struct kvmi_interception { DECLARE_BITMAP(low, KVMI_NUM_MSR); DECLARE_BITMAP(high, KVMI_NUM_MSR); } kvmi_mask; + struct { + DECLARE_BITMAP(low, KVMI_NUM_MSR); + DECLARE_BITMAP(high, KVMI_NUM_MSR); + } kvm_mask; + bool (*monitor_fct)(struct kvm_vcpu *vcpu, u32 msr, + bool enable); } msrw; }; @@ -44,6 +50,8 @@ void kvmi_xsetbv_event(struct kvm_vcpu *vcpu); bool kvmi_monitor_desc_intercept(struct kvm_vcpu *vcpu, bool enable); bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, u8 write); bool kvmi_msr_event(struct kvm_vcpu *vcpu, struct msr_data *msr); +bool kvmi_monitor_msrw_intercept(struct kvm_vcpu *vcpu, u32 msr, bool enable); +bool kvmi_msrw_intercept_originator(struct kvm_vcpu *vcpu); #else /* CONFIG_KVM_INTROSPECTION */ @@ -62,6 +70,10 @@ static inline bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, u8 write) { return true; } static inline bool kvmi_msr_event(struct kvm_vcpu *vcpu, struct msr_data *msr) { return true; } +static inline bool kvmi_monitor_msrw_intercept(struct kvm_vcpu *vcpu, u32 msr, + bool enable) { return false; } +static inline bool kvmi_msrw_intercept_originator(struct kvm_vcpu *vcpu) + { return false; } #endif /* CONFIG_KVM_INTROSPECTION */ diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c index 7705ac155c84..bed6e02697ca 100644 --- a/arch/x86/kvm/kvmi.c +++ b/arch/x86/kvm/kvmi.c @@ -369,22 +369,25 @@ static void kvmi_arch_disable_desc_intercept(struct kvm_vcpu *vcpu) vcpu->arch.kvmi->descriptor.kvm_intercepted = false; } -static unsigned long *msr_mask(struct kvm_vcpu *vcpu, unsigned int *msr) +static unsigned long *msr_mask(struct kvm_vcpu *vcpu, unsigned int *msr, + bool kvmi) { switch (*msr) { case 0 ... 0x1fff: - return vcpu->arch.kvmi->msrw.kvmi_mask.low; + return kvmi ? vcpu->arch.kvmi->msrw.kvmi_mask.low : + vcpu->arch.kvmi->msrw.kvm_mask.low; case 0xc0000000 ... 0xc0001fff: *msr &= 0x1fff; - return vcpu->arch.kvmi->msrw.kvmi_mask.high; + return kvmi ? vcpu->arch.kvmi->msrw.kvmi_mask.high : + vcpu->arch.kvmi->msrw.kvm_mask.high; } return NULL; } -static bool test_msr_mask(struct kvm_vcpu *vcpu, unsigned int msr) +static bool test_msr_mask(struct kvm_vcpu *vcpu, unsigned int msr, bool kvmi) { - unsigned long *mask = msr_mask(vcpu, &msr); + unsigned long *mask = msr_mask(vcpu, &msr, kvmi); if (!mask) return false; @@ -392,9 +395,27 @@ static bool test_msr_mask(struct kvm_vcpu *vcpu, unsigned int msr) return !!test_bit(msr, mask); } -static bool msr_control(struct kvm_vcpu *vcpu, unsigned int msr, bool enable) +/* + * Returns true if one side (kvm or kvmi) tries to disable the MSR write + * interception while the other side is still tracking it. + */ +bool kvmi_monitor_msrw_intercept(struct kvm_vcpu *vcpu, u32 msr, bool enable) +{ + struct kvmi_interception *arch_vcpui; + + if (!vcpu) + return false; + + arch_vcpui = READ_ONCE(vcpu->arch.kvmi); + + return (arch_vcpui && arch_vcpui->msrw.monitor_fct(vcpu, msr, enable)); +} +EXPORT_SYMBOL(kvmi_monitor_msrw_intercept); + +static bool msr_control(struct kvm_vcpu *vcpu, unsigned int msr, bool enable, + bool kvmi) { - unsigned long *mask = msr_mask(vcpu, &msr); + unsigned long *mask = msr_mask(vcpu, &msr, kvmi); if (!mask) return false; @@ -407,6 +428,63 @@ static bool msr_control(struct kvm_vcpu *vcpu, unsigned int msr, bool enable) return true; } +static bool msr_intercepted_by_kvmi(struct kvm_vcpu *vcpu, u32 msr) +{ + return test_msr_mask(vcpu, msr, true); +} + +static bool msr_intercepted_by_kvm(struct kvm_vcpu *vcpu, u32 msr) +{ + return test_msr_mask(vcpu, msr, false); +} + +static void record_msr_intercept_status_for_kvmi(struct kvm_vcpu *vcpu, u32 msr, + bool enable) +{ + msr_control(vcpu, msr, enable, true); +} + +static void record_msr_intercept_status_for_kvm(struct kvm_vcpu *vcpu, u32 msr, + bool enable) +{ + msr_control(vcpu, msr, enable, false); +} + +static bool monitor_msrw_fct_kvmi(struct kvm_vcpu *vcpu, u32 msr, bool enable) +{ + bool ret = false; + + if (enable) { + if (kvm_x86_ops->msr_write_intercepted(vcpu, msr)) + record_msr_intercept_status_for_kvm(vcpu, msr, true); + } else { + if (unlikely(!msr_intercepted_by_kvmi(vcpu, msr))) + ret = true; + + if (msr_intercepted_by_kvm(vcpu, msr)) + ret = true; + } + + record_msr_intercept_status_for_kvmi(vcpu, msr, enable); + + return ret; +} + +static bool monitor_msrw_fct_kvm(struct kvm_vcpu *vcpu, u32 msr, bool enable) +{ + bool ret = false; + + if (!(msr_intercepted_by_kvmi(vcpu, msr))) + return false; + + if (!enable) + ret = true; + + record_msr_intercept_status_for_kvm(vcpu, msr, enable); + + return ret; +} + static unsigned int msr_mask_to_base(struct kvm_vcpu *vcpu, unsigned long *mask) { if (mask == vcpu->arch.kvmi->msrw.kvmi_mask.high) @@ -415,6 +493,14 @@ static unsigned int msr_mask_to_base(struct kvm_vcpu *vcpu, unsigned long *mask) return 0; } +static void kvmi_control_msrw_intercept(struct kvm_vcpu *vcpu, u32 msr, + bool enable) +{ + vcpu->arch.kvmi->msrw.monitor_fct = monitor_msrw_fct_kvmi; + kvm_x86_ops->control_msr_intercept(vcpu, msr, MSR_TYPE_W, enable); + vcpu->arch.kvmi->msrw.monitor_fct = monitor_msrw_fct_kvm; +} + static void kvmi_arch_disable_msr_intercept(struct kvm_vcpu *vcpu, unsigned long *mask) { @@ -427,9 +513,7 @@ static void kvmi_arch_disable_msr_intercept(struct kvm_vcpu *vcpu, if (offset >= KVMI_NUM_MSR) break; - kvm_x86_ops->control_msr_intercept(vcpu, msr_base + offset, - MSR_TYPE_W, false); - msr_control(vcpu, msr_base + offset, false); + kvmi_control_msrw_intercept(vcpu, msr_base + offset, false); } bitmap_zero(mask, KVMI_NUM_MSR); @@ -501,12 +585,14 @@ bool kvmi_arch_vcpu_alloc(struct kvm_vcpu *vcpu) arch_vcpui->breakpoint.monitor_fct = monitor_bp_fct_kvm; arch_vcpui->cr3w.monitor_fct = monitor_cr3w_fct_kvm; arch_vcpui->descriptor.monitor_fct = monitor_desc_fct_kvm; + arch_vcpui->msrw.monitor_fct = monitor_msrw_fct_kvm; /* * paired with: * - kvmi_monitor_bp_intercept() * - kvmi_monitor_cr3w_intercept() * - kvmi_monitor_desc_intercept() + * - kvmi_monitor_msrw_intercept() */ smp_wmb(); WRITE_ONCE(vcpu->arch.kvmi, arch_vcpui); @@ -823,6 +909,13 @@ static bool kvmi_msr_valid(unsigned int msr) return false; } +bool kvmi_msrw_intercept_originator(struct kvm_vcpu *vcpu) +{ + struct kvmi_interception *arch = vcpu->arch.kvmi; + + return (arch && arch->msrw.monitor_fct == monitor_msrw_fct_kvmi); +} +EXPORT_SYMBOL(kvmi_msrw_intercept_originator); int kvmi_arch_cmd_vcpu_control_msr(struct kvm_vcpu *vcpu, const struct kvmi_vcpu_control_msr *req) @@ -833,9 +926,7 @@ int kvmi_arch_cmd_vcpu_control_msr(struct kvm_vcpu *vcpu, if (!kvmi_msr_valid(req->msr)) return -KVM_EINVAL; - kvm_x86_ops->control_msr_intercept(vcpu, req->msr, MSR_TYPE_W, - req->enable); - msr_control(vcpu, req->msr, req->enable); + kvmi_control_msrw_intercept(vcpu, req->msr, req->enable); return 0; } @@ -872,7 +963,7 @@ static bool __kvmi_msr_event(struct kvm_vcpu *vcpu, struct msr_data *msr) u64 ret_value; u32 action; - if (!test_msr_mask(vcpu, msr->index)) + if (!test_msr_mask(vcpu, msr->index, true)) return true; if (kvm_x86_ops->get_msr(vcpu, &old_msr)) return true; diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 7cd48ef25f59..309a7e5e8b62 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1085,6 +1085,17 @@ static void set_msr_interception(struct kvm_vcpu *vcpu, unsigned long tmp; u32 offset; +#ifdef CONFIG_KVM_INTROSPECTION + if ((type & MSR_TYPE_W) && + kvmi_monitor_msrw_intercept(vcpu, msr, !value)) + type &= ~MSR_TYPE_W; + + /* + * Avoid the below warning for kvmi intercepted msrs. + */ + if (!kvmi_msrw_intercept_originator(vcpu)) +#endif /* CONFIG_KVM_INTROSPECTION */ + /* * If this warning triggers extend the direct_access_msrs list at the * beginning of the file diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index e423dbbf3cf5..2aaa74caefff 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3630,6 +3630,12 @@ static __always_inline void vmx_disable_intercept_for_msr(struct kvm_vcpu *vcpu, if (!cpu_has_vmx_msr_bitmap()) return; +#ifdef CONFIG_KVM_INTROSPECTION + if ((type & MSR_TYPE_W) && + kvmi_monitor_msrw_intercept(vcpu, msr, false)) + type &= ~MSR_TYPE_W; +#endif /* CONFIG_KVM_INTROSPECTION */ + if (static_branch_unlikely(&enable_evmcs)) evmcs_touch_msr_bitmap(); @@ -3669,6 +3675,11 @@ static __always_inline void vmx_enable_intercept_for_msr(struct kvm_vcpu *vcpu, if (!cpu_has_vmx_msr_bitmap()) return; +#ifdef CONFIG_KVM_INTROSPECTION + if (type & MSR_TYPE_W) + kvmi_monitor_msrw_intercept(vcpu, msr, true); +#endif /* CONFIG_KVM_INTROSPECTION */ + if (static_branch_unlikely(&enable_evmcs)) evmcs_touch_msr_bitmap(); _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
