1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/tboot.h>
  3
  4#include <asm/cpu.h>
  5#include <asm/cpufeature.h>
  6#include <asm/msr-index.h>
  7#include <asm/processor.h>
  8#include <asm/vmx.h>
  9
 10#undef pr_fmt
 11#define pr_fmt(fmt)	"x86/cpu: " fmt
 12
 13#ifdef CONFIG_X86_VMX_FEATURE_NAMES
 14enum vmx_feature_leafs {
 15	MISC_FEATURES = 0,
 16	PRIMARY_CTLS,
 17	SECONDARY_CTLS,
 18	TERTIARY_CTLS_LOW,
 19	TERTIARY_CTLS_HIGH,
 20	NR_VMX_FEATURE_WORDS,
 21};
 22
 23#define VMX_F(x) BIT(VMX_FEATURE_##x & 0x1f)
 24
 25static void init_vmx_capabilities(struct cpuinfo_x86 *c)
 26{
 27	u32 supported, funcs, ept, vpid, ign, low, high;
 28
 29	BUILD_BUG_ON(NVMXINTS != NR_VMX_FEATURE_WORDS);
 30
 31	/*
 32	 * The high bits contain the allowed-1 settings, i.e. features that can
 33	 * be turned on.  The low bits contain the allowed-0 settings, i.e.
 34	 * features that can be turned off.  Ignore the allowed-0 settings,
 35	 * if a feature can be turned on then it's supported.
 36	 *
 37	 * Use raw rdmsr() for primary processor controls and pin controls MSRs
 38	 * as they exist on any CPU that supports VMX, i.e. we want the WARN if
 39	 * the RDMSR faults.
 40	 */
 41	rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, ign, supported);
 42	c->vmx_capability[PRIMARY_CTLS] = supported;
 43
 44	rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS2, &ign, &supported);
 45	c->vmx_capability[SECONDARY_CTLS] = supported;
 46
 47	/* All 64 bits of tertiary controls MSR are allowed-1 settings. */
 48	rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS3, &low, &high);
 49	c->vmx_capability[TERTIARY_CTLS_LOW] = low;
 50	c->vmx_capability[TERTIARY_CTLS_HIGH] = high;
 51
 52	rdmsr(MSR_IA32_VMX_PINBASED_CTLS, ign, supported);
 53	rdmsr_safe(MSR_IA32_VMX_VMFUNC, &ign, &funcs);
 54
 55	/*
 56	 * Except for EPT+VPID, which enumerates support for both in a single
 57	 * MSR, low for EPT, high for VPID.
 58	 */
 59	rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, &ept, &vpid);
 60
 61	/* Pin, EPT, VPID and VM-Func are merged into a single word. */
 62	WARN_ON_ONCE(supported >> 16);
 63	WARN_ON_ONCE(funcs >> 4);
 64	c->vmx_capability[MISC_FEATURES] = (supported & 0xffff) |
 65					   ((vpid & 0x1) << 16) |
 66					   ((funcs & 0xf) << 28);
 67
 68	/* EPT bits are full on scattered and must be manually handled. */
 69	if (ept & VMX_EPT_EXECUTE_ONLY_BIT)
 70		c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_EXECUTE_ONLY);
 71	if (ept & VMX_EPT_AD_BIT)
 72		c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_AD);
 73	if (ept & VMX_EPT_1GB_PAGE_BIT)
 74		c->vmx_capability[MISC_FEATURES] |= VMX_F(EPT_1GB);
 75
 76	/* Synthetic APIC features that are aggregates of multiple features. */
 77	if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) &&
 78	    (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_APIC_ACCESSES)))
 79		c->vmx_capability[MISC_FEATURES] |= VMX_F(FLEXPRIORITY);
 80
 81	if ((c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR)) &&
 82	    (c->vmx_capability[SECONDARY_CTLS] & VMX_F(APIC_REGISTER_VIRT)) &&
 83	    (c->vmx_capability[SECONDARY_CTLS] & VMX_F(VIRT_INTR_DELIVERY)) &&
 84	    (c->vmx_capability[MISC_FEATURES] & VMX_F(POSTED_INTR)))
 85		c->vmx_capability[MISC_FEATURES] |= VMX_F(APICV);
 86
 87	/* Set the synthetic cpufeatures to preserve /proc/cpuinfo's ABI. */
 88	if (c->vmx_capability[PRIMARY_CTLS] & VMX_F(VIRTUAL_TPR))
 89		set_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
 90	if (c->vmx_capability[MISC_FEATURES] & VMX_F(FLEXPRIORITY))
 91		set_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
 92	if (c->vmx_capability[MISC_FEATURES] & VMX_F(VIRTUAL_NMIS))
 93		set_cpu_cap(c, X86_FEATURE_VNMI);
 94	if (c->vmx_capability[SECONDARY_CTLS] & VMX_F(EPT))
 95		set_cpu_cap(c, X86_FEATURE_EPT);
 96	if (c->vmx_capability[MISC_FEATURES] & VMX_F(EPT_AD))
 97		set_cpu_cap(c, X86_FEATURE_EPT_AD);
 98	if (c->vmx_capability[MISC_FEATURES] & VMX_F(VPID))
 99		set_cpu_cap(c, X86_FEATURE_VPID);
100}
101#endif /* CONFIG_X86_VMX_FEATURE_NAMES */
102
103static int __init nosgx(char *str)
104{
105	setup_clear_cpu_cap(X86_FEATURE_SGX);
106
107	return 0;
108}
109
110early_param("nosgx", nosgx);
111
112void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
113{
114	bool enable_sgx_kvm = false, enable_sgx_driver = false;
115	bool tboot = tboot_enabled();
116	bool enable_vmx;
117	u64 msr;
118
119	if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) {
120		clear_cpu_cap(c, X86_FEATURE_VMX);
121		clear_cpu_cap(c, X86_FEATURE_SGX);
122		return;
123	}
124
125	enable_vmx = cpu_has(c, X86_FEATURE_VMX) &&
126		     IS_ENABLED(CONFIG_KVM_INTEL);
127
128	if (cpu_has(c, X86_FEATURE_SGX) && IS_ENABLED(CONFIG_X86_SGX)) {
129		/*
130		 * Separate out SGX driver enabling from KVM.  This allows KVM
131		 * guests to use SGX even if the kernel SGX driver refuses to
132		 * use it.  This happens if flexible Launch Control is not
133		 * available.
134		 */
135		enable_sgx_driver = cpu_has(c, X86_FEATURE_SGX_LC);
136		enable_sgx_kvm = enable_vmx && IS_ENABLED(CONFIG_X86_SGX_KVM);
137	}
138
139	if (msr & FEAT_CTL_LOCKED)
140		goto update_caps;
141
142	/*
143	 * Ignore whatever value BIOS left in the MSR to avoid enabling random
144	 * features or faulting on the WRMSR.
145	 */
146	msr = FEAT_CTL_LOCKED;
147
148	/*
149	 * Enable VMX if and only if the kernel may do VMXON at some point,
150	 * i.e. KVM is enabled, to avoid unnecessarily adding an attack vector
151	 * for the kernel, e.g. using VMX to hide malicious code.
152	 */
153	if (enable_vmx) {
154		msr |= FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX;
155
156		if (tboot)
157			msr |= FEAT_CTL_VMX_ENABLED_INSIDE_SMX;
158	}
159
160	if (enable_sgx_kvm || enable_sgx_driver) {
161		msr |= FEAT_CTL_SGX_ENABLED;
162		if (enable_sgx_driver)
163			msr |= FEAT_CTL_SGX_LC_ENABLED;
164	}
165
166	wrmsrl(MSR_IA32_FEAT_CTL, msr);
167
168update_caps:
169	set_cpu_cap(c, X86_FEATURE_MSR_IA32_FEAT_CTL);
170
171	if (!cpu_has(c, X86_FEATURE_VMX))
172		goto update_sgx;
173
174	if ( (tboot && !(msr & FEAT_CTL_VMX_ENABLED_INSIDE_SMX)) ||
175	    (!tboot && !(msr & FEAT_CTL_VMX_ENABLED_OUTSIDE_SMX))) {
176		if (IS_ENABLED(CONFIG_KVM_INTEL))
177			pr_err_once("VMX (%s TXT) disabled by BIOS\n",
178				    tboot ? "inside" : "outside");
179		clear_cpu_cap(c, X86_FEATURE_VMX);
180	} else {
181#ifdef CONFIG_X86_VMX_FEATURE_NAMES
182		init_vmx_capabilities(c);
183#endif
184	}
185
186update_sgx:
187	if (!(msr & FEAT_CTL_SGX_ENABLED)) {
188		if (enable_sgx_kvm || enable_sgx_driver)
189			pr_err_once("SGX disabled by BIOS.\n");
190		clear_cpu_cap(c, X86_FEATURE_SGX);
191		return;
192	}
193
194	/*
195	 * VMX feature bit may be cleared due to being disabled in BIOS,
196	 * in which case SGX virtualization cannot be supported either.
197	 */
198	if (!cpu_has(c, X86_FEATURE_VMX) && enable_sgx_kvm) {
199		pr_err_once("SGX virtualization disabled due to lack of VMX.\n");
200		enable_sgx_kvm = 0;
201	}
202
203	if (!(msr & FEAT_CTL_SGX_LC_ENABLED) && enable_sgx_driver) {
204		if (!enable_sgx_kvm) {
205			pr_err_once("SGX Launch Control is locked. Disable SGX.\n");
206			clear_cpu_cap(c, X86_FEATURE_SGX);
207		} else {
208			pr_err_once("SGX Launch Control is locked. Support SGX virtualization only.\n");
209			clear_cpu_cap(c, X86_FEATURE_SGX_LC);
210		}
211	}
212}