diff options
Diffstat (limited to 'arch/x86/kvm/vmx.c')
-rw-r--r-- | arch/x86/kvm/vmx.c | 455 |
1 files changed, 377 insertions, 78 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 5d8e317c2b04..46b428c0990e 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -188,6 +188,150 @@ module_param(ple_window_max, uint, 0444); extern const ulong vmx_return; +static DEFINE_STATIC_KEY_FALSE(vmx_l1d_should_flush); +static DEFINE_STATIC_KEY_FALSE(vmx_l1d_flush_cond); +static DEFINE_MUTEX(vmx_l1d_flush_mutex); + +/* Storage for pre module init parameter parsing */ +static enum vmx_l1d_flush_state __read_mostly vmentry_l1d_flush_param = VMENTER_L1D_FLUSH_AUTO; + +static const struct { + const char *option; + enum vmx_l1d_flush_state cmd; +} vmentry_l1d_param[] = { + {"auto", VMENTER_L1D_FLUSH_AUTO}, + {"never", VMENTER_L1D_FLUSH_NEVER}, + {"cond", VMENTER_L1D_FLUSH_COND}, + {"always", VMENTER_L1D_FLUSH_ALWAYS}, +}; + +#define L1D_CACHE_ORDER 4 +static void *vmx_l1d_flush_pages; + +static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) +{ + struct page *page; + unsigned int i; + + if (!enable_ept) { + l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_EPT_DISABLED; + return 0; + } + + if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES)) { + u64 msr; + + rdmsrl(MSR_IA32_ARCH_CAPABILITIES, msr); + if (msr & ARCH_CAP_SKIP_VMENTRY_L1DFLUSH) { + l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NOT_REQUIRED; + return 0; + } + } + + /* If set to auto use the default l1tf mitigation method */ + if (l1tf == VMENTER_L1D_FLUSH_AUTO) { + switch (l1tf_mitigation) { + case L1TF_MITIGATION_OFF: + l1tf = VMENTER_L1D_FLUSH_NEVER; + break; + case L1TF_MITIGATION_FLUSH_NOWARN: + case L1TF_MITIGATION_FLUSH: + case L1TF_MITIGATION_FLUSH_NOSMT: + l1tf = VMENTER_L1D_FLUSH_COND; + break; + case L1TF_MITIGATION_FULL: + case L1TF_MITIGATION_FULL_FORCE: + l1tf = VMENTER_L1D_FLUSH_ALWAYS; + break; + } + } else if (l1tf_mitigation == L1TF_MITIGATION_FULL_FORCE) { + l1tf = VMENTER_L1D_FLUSH_ALWAYS; + } + + if (l1tf != VMENTER_L1D_FLUSH_NEVER && !vmx_l1d_flush_pages && + !boot_cpu_has(X86_FEATURE_FLUSH_L1D)) { + page = alloc_pages(GFP_KERNEL, L1D_CACHE_ORDER); + if (!page) + return -ENOMEM; + vmx_l1d_flush_pages = page_address(page); + + /* + * Initialize each page with a different pattern in + * order to protect against KSM in the nested + * virtualization case. + */ + for (i = 0; i < 1u << L1D_CACHE_ORDER; ++i) { + memset(vmx_l1d_flush_pages + i * PAGE_SIZE, i + 1, + PAGE_SIZE); + } + } + + l1tf_vmx_mitigation = l1tf; + + if (l1tf != VMENTER_L1D_FLUSH_NEVER) + static_branch_enable(&vmx_l1d_should_flush); + else + static_branch_disable(&vmx_l1d_should_flush); + + if (l1tf == VMENTER_L1D_FLUSH_COND) + static_branch_enable(&vmx_l1d_flush_cond); + else + static_branch_disable(&vmx_l1d_flush_cond); + return 0; +} + +static int vmentry_l1d_flush_parse(const char *s) +{ + unsigned int i; + + if (s) { + for (i = 0; i < ARRAY_SIZE(vmentry_l1d_param); i++) { + if (sysfs_streq(s, vmentry_l1d_param[i].option)) + return vmentry_l1d_param[i].cmd; + } + } + return -EINVAL; +} + +static int vmentry_l1d_flush_set(const char *s, const struct kernel_param *kp) +{ + int l1tf, ret; + + if (!boot_cpu_has(X86_BUG_L1TF)) + return 0; + + l1tf = vmentry_l1d_flush_parse(s); + if (l1tf < 0) + return l1tf; + + /* + * Has vmx_init() run already? If not then this is the pre init + * parameter parsing. In that case just store the value and let + * vmx_init() do the proper setup after enable_ept has been + * established. + */ + if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO) { + vmentry_l1d_flush_param = l1tf; + return 0; + } + + mutex_lock(&vmx_l1d_flush_mutex); + ret = vmx_setup_l1d_flush(l1tf); + mutex_unlock(&vmx_l1d_flush_mutex); + return ret; +} + +static int vmentry_l1d_flush_get(char *s, const struct kernel_param *kp) +{ + return sprintf(s, "%s\n", vmentry_l1d_param[l1tf_vmx_mitigation].option); +} + +static const struct kernel_param_ops vmentry_l1d_flush_ops = { + .set = vmentry_l1d_flush_set, + .get = vmentry_l1d_flush_get, +}; +module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, NULL, 0644); + struct kvm_vmx { struct kvm kvm; @@ -757,6 +901,11 @@ static inline int pi_test_sn(struct pi_desc *pi_desc) (unsigned long *)&pi_desc->control); } +struct vmx_msrs { + unsigned int nr; + struct vmx_msr_entry val[NR_AUTOLOAD_MSRS]; +}; + struct vcpu_vmx { struct kvm_vcpu vcpu; unsigned long host_rsp; @@ -790,9 +939,8 @@ struct vcpu_vmx { struct loaded_vmcs *loaded_vmcs; bool __launched; /* temporary, used in vmx_vcpu_run */ struct msr_autoload { - unsigned nr; - struct vmx_msr_entry guest[NR_AUTOLOAD_MSRS]; - struct vmx_msr_entry host[NR_AUTOLOAD_MSRS]; + struct vmx_msrs guest; + struct vmx_msrs host; } msr_autoload; struct { int loaded; @@ -2377,9 +2525,20 @@ static void clear_atomic_switch_msr_special(struct vcpu_vmx *vmx, vm_exit_controls_clearbit(vmx, exit); } +static int find_msr(struct vmx_msrs *m, unsigned int msr) +{ + unsigned int i; + + for (i = 0; i < m->nr; ++i) { + if (m->val[i].index == msr) + return i; + } + return -ENOENT; +} + static void clear_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr) { - unsigned i; + int i; struct msr_autoload *m = &vmx->msr_autoload; switch (msr) { @@ -2400,18 +2559,21 @@ static void clear_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr) } break; } + i = find_msr(&m->guest, msr); + if (i < 0) + goto skip_guest; + --m->guest.nr; + m->guest.val[i] = m->guest.val[m->guest.nr]; + vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->guest.nr); - for (i = 0; i < m->nr; ++i) - if (m->guest[i].index == msr) - break; - - if (i == m->nr) +skip_guest: + i = find_msr(&m->host, msr); + if (i < 0) return; - --m->nr; - m->guest[i] = m->guest[m->nr]; - m->host[i] = m->host[m->nr]; - vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->nr); - vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->nr); + + --m->host.nr; + m->host.val[i] = m->host.val[m->host.nr]; + vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->host.nr); } static void add_atomic_switch_msr_special(struct vcpu_vmx *vmx, @@ -2426,9 +2588,9 @@ static void add_atomic_switch_msr_special(struct vcpu_vmx *vmx, } static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr, - u64 guest_val, u64 host_val) + u64 guest_val, u64 host_val, bool entry_only) { - unsigned i; + int i, j = 0; struct msr_autoload *m = &vmx->msr_autoload; switch (msr) { @@ -2463,24 +2625,31 @@ static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr, wrmsrl(MSR_IA32_PEBS_ENABLE, 0); } - for (i = 0; i < m->nr; ++i) - if (m->guest[i].index == msr) - break; + i = find_msr(&m->guest, msr); + if (!entry_only) + j = find_msr(&m->host, msr); - if (i == NR_AUTOLOAD_MSRS) { + if (i == NR_AUTOLOAD_MSRS || j == NR_AUTOLOAD_MSRS) { printk_once(KERN_WARNING "Not enough msr switch entries. " "Can't add msr %x\n", msr); return; - } else if (i == m->nr) { - ++m->nr; - vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->nr); - vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->nr); } + if (i < 0) { + i = m->guest.nr++; + vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->guest.nr); + } + m->guest.val[i].index = msr; + m->guest.val[i].value = guest_val; + + if (entry_only) + return; - m->guest[i].index = msr; - m->guest[i].value = guest_val; - m->host[i].index = msr; - m->host[i].value = host_val; + if (j < 0) { + j = m->host.nr++; + vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->host.nr); + } + m->host.val[j].index = msr; + m->host.val[j].value = host_val; } static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset) @@ -2524,7 +2693,7 @@ static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset) guest_efer &= ~EFER_LME; if (guest_efer != host_efer) add_atomic_switch_msr(vmx, MSR_EFER, - guest_efer, host_efer); + guest_efer, host_efer, false); return false; } else { guest_efer &= ~ignore_bits; @@ -3987,7 +4156,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vcpu->arch.ia32_xss = data; if (vcpu->arch.ia32_xss != host_xss) add_atomic_switch_msr(vmx, MSR_IA32_XSS, - vcpu->arch.ia32_xss, host_xss); + vcpu->arch.ia32_xss, host_xss, false); else clear_atomic_switch_msr(vmx, MSR_IA32_XSS); break; @@ -6274,9 +6443,9 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx) vmcs_write32(VM_EXIT_MSR_STORE_COUNT, 0); vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, 0); - vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host)); + vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host.val)); vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, 0); - vmcs_write64(VM_ENTRY_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.guest)); + vmcs_write64(VM_ENTRY_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.guest.val)); if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) vmcs_write64(GUEST_IA32_PAT, vmx->vcpu.arch.pat); @@ -6296,8 +6465,7 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx) ++vmx->nmsrs; } - if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES)) - rdmsrl(MSR_IA32_ARCH_CAPABILITIES, vmx->arch_capabilities); + vmx->arch_capabilities = kvm_get_arch_capabilities(); vm_exit_controls_init(vmx, vmcs_config.vmexit_ctrl); @@ -9548,6 +9716,79 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) } } +/* + * Software based L1D cache flush which is used when microcode providing + * the cache control MSR is not loaded. + * + * The L1D cache is 32 KiB on Nehalem and later microarchitectures, but to + * flush it is required to read in 64 KiB because the replacement algorithm + * is not exactly LRU. This could be sized at runtime via topology + * information but as all relevant affected CPUs have 32KiB L1D cache size + * there is no point in doing so. + */ +#define L1D_CACHE_ORDER 4 +static void *vmx_l1d_flush_pages; + +static void vmx_l1d_flush(struct kvm_vcpu *vcpu) +{ + int size = PAGE_SIZE << L1D_CACHE_ORDER; + + /* + * This code is only executed when the the flush mode is 'cond' or + * 'always' + */ + if (static_branch_likely(&vmx_l1d_flush_cond)) { + bool flush_l1d; + + /* + * Clear the per-vcpu flush bit, it gets set again + * either from vcpu_run() or from one of the unsafe + * VMEXIT handlers. + */ + flush_l1d = vcpu->arch.l1tf_flush_l1d; + vcpu->arch.l1tf_flush_l1d = false; + + /* + * Clear the per-cpu flush bit, it gets set again from + * the interrupt handlers. + */ + flush_l1d |= kvm_get_cpu_l1tf_flush_l1d(); + kvm_clear_cpu_l1tf_flush_l1d(); + + if (!flush_l1d) + return; + } + + vcpu->stat.l1d_flush++; + + if (static_cpu_has(X86_FEATURE_FLUSH_L1D)) { + wrmsrl(MSR_IA32_FLUSH_CMD, L1D_FLUSH); + return; + } + + asm volatile( + /* First ensure the pages are in the TLB */ + "xorl %%eax, %%eax\n" + ".Lpopulate_tlb:\n\t" + "movzbl (%[flush_pages], %%" _ASM_AX "), %%ecx\n\t" + "addl $4096, %%eax\n\t" + "cmpl %%eax, %[size]\n\t" + "jne .Lpopulate_tlb\n\t" + "xorl %%eax, %%eax\n\t" + "cpuid\n\t" + /* Now fill the cache */ + "xorl %%eax, %%eax\n" + ".Lfill_cache:\n" + "movzbl (%[flush_pages], %%" _ASM_AX "), %%ecx\n\t" + "addl $64, %%eax\n\t" + "cmpl %%eax, %[size]\n\t" + "jne .Lfill_cache\n\t" + "lfence\n" + :: [flush_pages] "r" (vmx_l1d_flush_pages), + [size] "r" (size) + : "eax", "ebx", "ecx", "edx"); +} + static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr) { struct vmcs12 *vmcs12 = get_vmcs12(vcpu); @@ -9949,7 +10190,7 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx) clear_atomic_switch_msr(vmx, msrs[i].msr); else add_atomic_switch_msr(vmx, msrs[i].msr, msrs[i].guest, - msrs[i].host); + msrs[i].host, false); } static void vmx_arm_hv_timer(struct kvm_vcpu *vcpu) @@ -10044,6 +10285,9 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu) evmcs_rsp = static_branch_unlikely(&enable_evmcs) ? (unsigned long)¤t_evmcs->host_rsp : 0; + if (static_branch_unlikely(&vmx_l1d_should_flush)) + vmx_l1d_flush(vcpu); + asm( /* Store host registers */ "push %%" _ASM_DX "; push %%" _ASM_BP ";" @@ -10403,10 +10647,37 @@ free_vcpu: return ERR_PTR(err); } +#define L1TF_MSG_SMT "L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details.\n" +#define L1TF_MSG_L1D "L1TF CPU bug present and virtualization mitigation disabled, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details.\n" + static int vmx_vm_init(struct kvm *kvm) { if (!ple_gap) kvm->arch.pause_in_guest = true; + + if (boot_cpu_has(X86_BUG_L1TF) && enable_ept) { + switch (l1tf_mitigation) { + case L1TF_MITIGATION_OFF: + case L1TF_MITIGATION_FLUSH_NOWARN: + /* 'I explicitly don't care' is set */ + break; + case L1TF_MITIGATION_FLUSH: + case L1TF_MITIGATION_FLUSH_NOSMT: + case L1TF_MITIGATION_FULL: + /* + * Warn upon starting the first VM in a potentially + * insecure environment. + */ + if (cpu_smt_control == CPU_SMT_ENABLED) + pr_warn_once(L1TF_MSG_SMT); + if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER) + pr_warn_once(L1TF_MSG_L1D); + break; + case L1TF_MITIGATION_FULL_FORCE: + /* Flush is enforced */ + break; + } + } return 0; } @@ -11260,10 +11531,10 @@ static void prepare_vmcs02_full(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) * Set the MSR load/store lists to match L0's settings. */ vmcs_write32(VM_EXIT_MSR_STORE_COUNT, 0); - vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.nr); - vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host)); - vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.nr); - vmcs_write64(VM_ENTRY_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.guest)); + vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr); + vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host.val)); + vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr); + vmcs_write64(VM_ENTRY_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.guest.val)); set_cr4_guest_host_mask(vmx); @@ -11899,6 +12170,9 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch) return ret; } + /* Hide L1D cache contents from the nested guest. */ + vmx->vcpu.arch.l1tf_flush_l1d = true; + /* * If we're entering a halted L2 vcpu and the L2 vcpu won't be woken * by event injection, halt vcpu. @@ -12419,8 +12693,8 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, vmx_segment_cache_clear(vmx); /* Update any VMCS fields that might have changed while L2 ran */ - vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.nr); - vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.nr); + vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr); + vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr); vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset); if (vmx->hv_deadline_tsc == -1) vmcs_clear_bits(PIN_BASED_VM_EXEC_CONTROL, @@ -13137,6 +13411,51 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { .enable_smi_window = enable_smi_window, }; +static void vmx_cleanup_l1d_flush(void) +{ + if (vmx_l1d_flush_pages) { + free_pages((unsigned long)vmx_l1d_flush_pages, L1D_CACHE_ORDER); + vmx_l1d_flush_pages = NULL; + } + /* Restore state so sysfs ignores VMX */ + l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; +} + +static void vmx_exit(void) +{ +#ifdef CONFIG_KEXEC_CORE + RCU_INIT_POINTER(crash_vmclear_loaded_vmcss, NULL); + synchronize_rcu(); +#endif + + kvm_exit(); + +#if IS_ENABLED(CONFIG_HYPERV) + if (static_branch_unlikely(&enable_evmcs)) { + int cpu; + struct hv_vp_assist_page *vp_ap; + /* + * Reset everything to support using non-enlightened VMCS + * access later (e.g. when we reload the module with + * enlightened_vmcs=0) + */ + for_each_online_cpu(cpu) { + vp_ap = hv_get_vp_assist_page(cpu); + + if (!vp_ap) + continue; + + vp_ap->current_nested_vmcs = 0; + vp_ap->enlighten_vmentry = 0; + } + + static_branch_disable(&enable_evmcs); + } +#endif + vmx_cleanup_l1d_flush(); +} +module_exit(vmx_exit); + static int __init vmx_init(void) { int r; @@ -13171,10 +13490,25 @@ static int __init vmx_init(void) #endif r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx), - __alignof__(struct vcpu_vmx), THIS_MODULE); + __alignof__(struct vcpu_vmx), THIS_MODULE); if (r) return r; + /* + * Must be called after kvm_init() so enable_ept is properly set + * up. Hand the parameter mitigation value in which was stored in + * the pre module init parser. If no parameter was given, it will + * contain 'auto' which will be turned into the default 'cond' + * mitigation mode. + */ + if (boot_cpu_has(X86_BUG_L1TF)) { + r = vmx_setup_l1d_flush(vmentry_l1d_flush_param); + if (r) { + vmx_exit(); + return r; + } + } + #ifdef CONFIG_KEXEC_CORE rcu_assign_pointer(crash_vmclear_loaded_vmcss, crash_vmclear_local_loaded_vmcss); @@ -13183,39 +13517,4 @@ static int __init vmx_init(void) return 0; } - -static void __exit vmx_exit(void) -{ -#ifdef CONFIG_KEXEC_CORE - RCU_INIT_POINTER(crash_vmclear_loaded_vmcss, NULL); - synchronize_rcu(); -#endif - - kvm_exit(); - -#if IS_ENABLED(CONFIG_HYPERV) - if (static_branch_unlikely(&enable_evmcs)) { - int cpu; - struct hv_vp_assist_page *vp_ap; - /* - * Reset everything to support using non-enlightened VMCS - * access later (e.g. when we reload the module with - * enlightened_vmcs=0) - */ - for_each_online_cpu(cpu) { - vp_ap = hv_get_vp_assist_page(cpu); - - if (!vp_ap) - continue; - - vp_ap->current_nested_vmcs = 0; - vp_ap->enlighten_vmentry = 0; - } - - static_branch_disable(&enable_evmcs); - } -#endif -} - -module_init(vmx_init) -module_exit(vmx_exit) +module_init(vmx_init); |