From cc440cdad5b7a4c1de12dace725209eb3e0cf663 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 13 May 2020 13:36:32 -0400 Subject: [PATCH] KVM: nSVM: implement KVM_GET_NESTED_STATE and KVM_SET_NESTED_STATE Similar to VMX, the state that is captured through the currently available IOCTLs is a mix of L1 and L2 state, dependent on whether the L2 guest was running at the moment when the process was interrupted to save its state. In particular, the SVM-specific state for nested virtualization includes the L1 saved state (including the interrupt flag), the cached L2 controls, and the GIF. Signed-off-by: Paolo Bonzini --- arch/x86/include/uapi/asm/kvm.h | 17 +++- arch/x86/kvm/cpuid.h | 5 ++ arch/x86/kvm/svm/nested.c | 147 ++++++++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 1 + arch/x86/kvm/vmx/nested.c | 5 -- arch/x86/kvm/x86.c | 3 +- 6 files changed, 171 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index 3f3f780c8c65..12075a9de1c1 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -385,18 +385,22 @@ struct kvm_sync_regs { #define KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT (1 << 4) #define KVM_STATE_NESTED_FORMAT_VMX 0 -#define KVM_STATE_NESTED_FORMAT_SVM 1 /* unused */ +#define KVM_STATE_NESTED_FORMAT_SVM 1 #define KVM_STATE_NESTED_GUEST_MODE 0x00000001 #define KVM_STATE_NESTED_RUN_PENDING 0x00000002 #define KVM_STATE_NESTED_EVMCS 0x00000004 #define KVM_STATE_NESTED_MTF_PENDING 0x00000008 +#define KVM_STATE_NESTED_GIF_SET 0x00000100 #define KVM_STATE_NESTED_SMM_GUEST_MODE 0x00000001 #define KVM_STATE_NESTED_SMM_VMXON 0x00000002 #define KVM_STATE_NESTED_VMX_VMCS_SIZE 0x1000 +#define KVM_STATE_NESTED_SVM_VMCB_SIZE 0x1000 + + struct kvm_vmx_nested_state_data { __u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE]; __u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE]; @@ -411,6 +415,15 @@ struct kvm_vmx_nested_state_hdr { } smm; }; +struct kvm_svm_nested_state_data { + /* Save area only used if KVM_STATE_NESTED_RUN_PENDING. */ + __u8 vmcb12[KVM_STATE_NESTED_SVM_VMCB_SIZE]; +}; + +struct kvm_svm_nested_state_hdr { + __u64 vmcb_pa; +}; + /* for KVM_CAP_NESTED_STATE */ struct kvm_nested_state { __u16 flags; @@ -419,6 +432,7 @@ struct kvm_nested_state { union { struct kvm_vmx_nested_state_hdr vmx; + struct kvm_svm_nested_state_hdr svm; /* Pad the header to 128 bytes. */ __u8 pad[120]; @@ -431,6 +445,7 @@ struct kvm_nested_state { */ union { struct kvm_vmx_nested_state_data vmx[0]; + struct kvm_svm_nested_state_data svm[0]; } data; }; diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 63a70f6a3df3..05434cd9342f 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -303,4 +303,9 @@ static __always_inline void kvm_cpu_cap_check_and_set(unsigned int x86_feature) kvm_cpu_cap_set(x86_feature); } +static inline bool page_address_valid(struct kvm_vcpu *vcpu, gpa_t gpa) +{ + return PAGE_ALIGNED(gpa) && !(gpa >> cpuid_maxphyaddr(vcpu)); +} + #endif diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index c712fe577029..6b1049148c1b 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -25,6 +25,7 @@ #include "trace.h" #include "mmu.h" #include "x86.h" +#include "cpuid.h" #include "lapic.h" #include "svm.h" @@ -238,6 +239,8 @@ static void load_nested_vmcb_control(struct vcpu_svm *svm, { copy_vmcb_control_area(&svm->nested.ctl, control); + /* Copy it here because nested_svm_check_controls will check it. */ + svm->nested.ctl.asid = control->asid; svm->nested.ctl.msrpm_base_pa &= ~0x0fffULL; svm->nested.ctl.iopm_base_pa &= ~0x0fffULL; } @@ -930,6 +933,150 @@ int nested_svm_exit_special(struct vcpu_svm *svm) return NESTED_EXIT_CONTINUE; } +static int svm_get_nested_state(struct kvm_vcpu *vcpu, + struct kvm_nested_state __user *user_kvm_nested_state, + u32 user_data_size) +{ + struct vcpu_svm *svm; + struct kvm_nested_state kvm_state = { + .flags = 0, + .format = KVM_STATE_NESTED_FORMAT_SVM, + .size = sizeof(kvm_state), + }; + struct vmcb __user *user_vmcb = (struct vmcb __user *) + &user_kvm_nested_state->data.svm[0]; + + if (!vcpu) + return kvm_state.size + KVM_STATE_NESTED_SVM_VMCB_SIZE; + + svm = to_svm(vcpu); + + if (user_data_size < kvm_state.size) + goto out; + + /* First fill in the header and copy it out. */ + if (is_guest_mode(vcpu)) { + kvm_state.hdr.svm.vmcb_pa = svm->nested.vmcb; + kvm_state.size += KVM_STATE_NESTED_SVM_VMCB_SIZE; + kvm_state.flags |= KVM_STATE_NESTED_GUEST_MODE; + + if (svm->nested.nested_run_pending) + kvm_state.flags |= KVM_STATE_NESTED_RUN_PENDING; + } + + if (gif_set(svm)) + kvm_state.flags |= KVM_STATE_NESTED_GIF_SET; + + if (copy_to_user(user_kvm_nested_state, &kvm_state, sizeof(kvm_state))) + return -EFAULT; + + if (!is_guest_mode(vcpu)) + goto out; + + /* + * Copy over the full size of the VMCB rather than just the size + * of the structs. + */ + if (clear_user(user_vmcb, KVM_STATE_NESTED_SVM_VMCB_SIZE)) + return -EFAULT; + if (copy_to_user(&user_vmcb->control, &svm->nested.ctl, + sizeof(user_vmcb->control))) + return -EFAULT; + if (copy_to_user(&user_vmcb->save, &svm->nested.hsave->save, + sizeof(user_vmcb->save))) + return -EFAULT; + +out: + return kvm_state.size; +} + +static int svm_set_nested_state(struct kvm_vcpu *vcpu, + struct kvm_nested_state __user *user_kvm_nested_state, + struct kvm_nested_state *kvm_state) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct vmcb *hsave = svm->nested.hsave; + struct vmcb __user *user_vmcb = (struct vmcb __user *) + &user_kvm_nested_state->data.svm[0]; + struct vmcb_control_area ctl; + struct vmcb_save_area save; + u32 cr0; + + if (kvm_state->format != KVM_STATE_NESTED_FORMAT_SVM) + return -EINVAL; + + if (kvm_state->flags & ~(KVM_STATE_NESTED_GUEST_MODE | + KVM_STATE_NESTED_RUN_PENDING | + KVM_STATE_NESTED_GIF_SET)) + return -EINVAL; + + /* + * If in guest mode, vcpu->arch.efer actually refers to the L2 guest's + * EFER.SVME, but EFER.SVME still has to be 1 for VMRUN to succeed. + */ + if (!(vcpu->arch.efer & EFER_SVME)) { + /* GIF=1 and no guest mode are required if SVME=0. */ + if (kvm_state->flags != KVM_STATE_NESTED_GIF_SET) + return -EINVAL; + } + + /* SMM temporarily disables SVM, so we cannot be in guest mode. */ + if (is_smm(vcpu) && (kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE)) + return -EINVAL; + + if (!(kvm_state->flags & KVM_STATE_NESTED_GUEST_MODE)) { + svm_leave_nested(svm); + goto out_set_gif; + } + + if (!page_address_valid(vcpu, kvm_state->hdr.svm.vmcb_pa)) + return -EINVAL; + if (kvm_state->size < sizeof(*kvm_state) + KVM_STATE_NESTED_SVM_VMCB_SIZE) + return -EINVAL; + if (copy_from_user(&ctl, &user_vmcb->control, sizeof(ctl))) + return -EFAULT; + if (copy_from_user(&save, &user_vmcb->save, sizeof(save))) + return -EFAULT; + + if (!nested_vmcb_check_controls(&ctl)) + return -EINVAL; + + /* + * Processor state contains L2 state. Check that it is + * valid for guest mode (see nested_vmcb_checks). + */ + cr0 = kvm_read_cr0(vcpu); + if (((cr0 & X86_CR0_CD) == 0) && (cr0 & X86_CR0_NW)) + return -EINVAL; + + /* + * Validate host state saved from before VMRUN (see + * nested_svm_check_permissions). + * TODO: validate reserved bits for all saved state. + */ + if (!(save.cr0 & X86_CR0_PG)) + return -EINVAL; + + /* + * All checks done, we can enter guest mode. L1 control fields + * come from the nested save state. Guest state is already + * in the registers, the save area of the nested state instead + * contains saved L1 state. + */ + copy_vmcb_control_area(&hsave->control, &svm->vmcb->control); + hsave->save = save; + + svm->nested.vmcb = kvm_state->hdr.svm.vmcb_pa; + load_nested_vmcb_control(svm, &ctl); + nested_prepare_vmcb_control(svm); + +out_set_gif: + svm_set_gif(svm, !!(kvm_state->flags & KVM_STATE_NESTED_GIF_SET)); + return 0; +} + struct kvm_x86_nested_ops svm_nested_ops = { .check_events = svm_check_nested_events, + .get_state = svm_get_nested_state, + .set_state = svm_set_nested_state, }; diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index b4db9a980469..3871bfb40594 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1193,6 +1193,7 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) svm->avic_is_running = true; svm->nested.hsave = page_address(hsave_page); + clear_page(svm->nested.hsave); svm->msrpm = page_address(msrpm_pages); svm_vcpu_init_msrpm(svm->msrpm); diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 51ebb60e1533..106fc6fceb97 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -437,11 +437,6 @@ static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu, } } -static bool page_address_valid(struct kvm_vcpu *vcpu, gpa_t gpa) -{ - return PAGE_ALIGNED(gpa) && !(gpa >> cpuid_maxphyaddr(vcpu)); -} - static int nested_vmx_check_io_bitmap_controls(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f0fa610bed91..d4aa7dc662d5 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4628,7 +4628,8 @@ long kvm_arch_vcpu_ioctl(struct file *filp, if (kvm_state.flags & ~(KVM_STATE_NESTED_RUN_PENDING | KVM_STATE_NESTED_GUEST_MODE - | KVM_STATE_NESTED_EVMCS | KVM_STATE_NESTED_MTF_PENDING)) + | KVM_STATE_NESTED_EVMCS | KVM_STATE_NESTED_MTF_PENDING + | KVM_STATE_NESTED_GIF_SET)) break; /* nested_run_pending implies guest_mode. */ -- GitLab