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