Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0-only */
       2             : /* CPU virtualization extensions handling
       3             :  *
       4             :  * This should carry the code for handling CPU virtualization extensions
       5             :  * that needs to live in the kernel core.
       6             :  *
       7             :  * Author: Eduardo Habkost <ehabkost@redhat.com>
       8             :  *
       9             :  * Copyright (C) 2008, Red Hat Inc.
      10             :  *
      11             :  * Contains code from KVM, Copyright (C) 2006 Qumranet, Inc.
      12             :  */
      13             : #ifndef _ASM_X86_VIRTEX_H
      14             : #define _ASM_X86_VIRTEX_H
      15             : 
      16             : #include <asm/processor.h>
      17             : 
      18             : #include <asm/vmx.h>
      19             : #include <asm/svm.h>
      20             : #include <asm/tlbflush.h>
      21             : 
      22             : /*
      23             :  * VMX functions:
      24             :  */
      25             : 
      26           0 : static inline int cpu_has_vmx(void)
      27             : {
      28           0 :         unsigned long ecx = cpuid_ecx(1);
      29           0 :         return test_bit(5, &ecx); /* CPUID.1:ECX.VMX[bit 5] -> VT */
      30             : }
      31             : 
      32             : 
      33             : /**
      34             :  * cpu_vmxoff() - Disable VMX on the current CPU
      35             :  *
      36             :  * Disable VMX and clear CR4.VMXE (even if VMXOFF faults)
      37             :  *
      38             :  * Note, VMXOFF causes a #UD if the CPU is !post-VMXON, but it's impossible to
      39             :  * atomically track post-VMXON state, e.g. this may be called in NMI context.
      40             :  * Eat all faults as all other faults on VMXOFF faults are mode related, i.e.
      41             :  * faults are guaranteed to be due to the !post-VMXON check unless the CPU is
      42             :  * magically in RM, VM86, compat mode, or at CPL>0.
      43             :  */
      44           0 : static inline int cpu_vmxoff(void)
      45             : {
      46           0 :         asm_volatile_goto("1: vmxoff\n\t"
      47             :                           _ASM_EXTABLE(1b, %l[fault])
      48             :                           ::: "cc", "memory" : fault);
      49             : 
      50           0 :         cr4_clear_bits(X86_CR4_VMXE);
      51           0 :         return 0;
      52             : 
      53           0 : fault:
      54           0 :         cr4_clear_bits(X86_CR4_VMXE);
      55           0 :         return -EIO;
      56             : }
      57             : 
      58           0 : static inline int cpu_vmx_enabled(void)
      59             : {
      60           0 :         return __read_cr4() & X86_CR4_VMXE;
      61             : }
      62             : 
      63             : /** Disable VMX if it is enabled on the current CPU
      64             :  *
      65             :  * You shouldn't call this if cpu_has_vmx() returns 0.
      66             :  */
      67           0 : static inline void __cpu_emergency_vmxoff(void)
      68             : {
      69           0 :         if (cpu_vmx_enabled())
      70           0 :                 cpu_vmxoff();
      71           0 : }
      72             : 
      73             : /** Disable VMX if it is supported and enabled on the current CPU
      74             :  */
      75           0 : static inline void cpu_emergency_vmxoff(void)
      76             : {
      77           0 :         if (cpu_has_vmx())
      78           0 :                 __cpu_emergency_vmxoff();
      79           0 : }
      80             : 
      81             : 
      82             : 
      83             : 
      84             : /*
      85             :  * SVM functions:
      86             :  */
      87             : 
      88             : /** Check if the CPU has SVM support
      89             :  *
      90             :  * You can use the 'msg' arg to get a message describing the problem,
      91             :  * if the function returns zero. Simply pass NULL if you are not interested
      92             :  * on the messages; gcc should take care of not generating code for
      93             :  * the messages on this case.
      94             :  */
      95             : static inline int cpu_has_svm(const char **msg)
      96             : {
      97             :         if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
      98             :             boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) {
      99             :                 if (msg)
     100             :                         *msg = "not amd or hygon";
     101             :                 return 0;
     102             :         }
     103             : 
     104             :         if (boot_cpu_data.extended_cpuid_level < SVM_CPUID_FUNC) {
     105             :                 if (msg)
     106             :                         *msg = "can't execute cpuid_8000000a";
     107             :                 return 0;
     108             :         }
     109             : 
     110             :         if (!boot_cpu_has(X86_FEATURE_SVM)) {
     111             :                 if (msg)
     112             :                         *msg = "svm not available";
     113             :                 return 0;
     114             :         }
     115             :         return 1;
     116             : }
     117             : 
     118             : 
     119             : /** Disable SVM on the current CPU
     120             :  *
     121             :  * You should call this only if cpu_has_svm() returned true.
     122             :  */
     123             : static inline void cpu_svm_disable(void)
     124             : {
     125             :         uint64_t efer;
     126             : 
     127             :         wrmsrl(MSR_VM_HSAVE_PA, 0);
     128             :         rdmsrl(MSR_EFER, efer);
     129             :         wrmsrl(MSR_EFER, efer & ~EFER_SVME);
     130             : }
     131             : 
     132             : /** Makes sure SVM is disabled, if it is supported on the CPU
     133             :  */
     134             : static inline void cpu_emergency_svm_disable(void)
     135             : {
     136             :         if (cpu_has_svm(NULL))
     137             :                 cpu_svm_disable();
     138             : }
     139             : 
     140             : #endif /* _ASM_X86_VIRTEX_H */