include/asm-x86/kvm_para.h

   1 #ifndef __X86_KVM_PARA_H
   2 #define __X86_KVM_PARA_H
   3
   4 /* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
   5  * should be used to determine that a VM is running under KVM.
   6  */
   7 #define KVM_CPUID_SIGNATURE     0x40000000
   8
   9 /* This CPUID returns a feature bitmap in eax.  Before enabling a particular
  10  * paravirtualization, the appropriate feature bit should be checked.
  11  */
  12 #define KVM_CPUID_FEATURES      0x40000001
  13
  14 #ifdef __KERNEL__
  15 #include <asm/processor.h>
  16
  17 /* This instruction is vmcall.  On non-VT architectures, it will generate a
  18  * trap that we will then rewrite to the appropriate instruction.
  19  */
  20 #define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
  21
  22 /* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
  23  * instruction.  The hypervisor may replace it with something else but only the
  24  * instructions are guaranteed to be supported.
  25  *
  26  * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
  27  * The hypercall number should be placed in rax and the return value will be
  28  * placed in rax.  No other registers will be clobbered unless explicited
  29  * noted by the particular hypercall.
  30  */
  31
  32 static inline long kvm_hypercall0(unsigned int nr)
  33 {
  34         long ret;
  35         asm volatile(KVM_HYPERCALL
  36                      : "=a"(ret)
  37                      : "a"(nr));
  38         return ret;
  39 }
  40
  41 static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
  42 {
  43         long ret;
  44         asm volatile(KVM_HYPERCALL
  45                      : "=a"(ret)
  46                      : "a"(nr), "b"(p1));
  47         return ret;
  48 }
  49
  50 static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
  51                                   unsigned long p2)
  52 {
  53         long ret;
  54         asm volatile(KVM_HYPERCALL
  55                      : "=a"(ret)
  56                      : "a"(nr), "b"(p1), "c"(p2));
  57         return ret;
  58 }
  59
  60 static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
  61                                   unsigned long p2, unsigned long p3)
  62 {
  63         long ret;
  64         asm volatile(KVM_HYPERCALL
  65                      : "=a"(ret)
  66                      : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
  67         return ret;
  68 }
  69
  70 static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
  71                                   unsigned long p2, unsigned long p3,
  72                                   unsigned long p4)
  73 {
  74         long ret;
  75         asm volatile(KVM_HYPERCALL
  76                      : "=a"(ret)
  77                      : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
  78         return ret;
  79 }
  80
  81 static inline int kvm_para_available(void)
  82 {
  83         unsigned int eax, ebx, ecx, edx;
  84         char signature[13];
  85
  86         cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
  87         memcpy(signature + 0, &ebx, 4);
  88         memcpy(signature + 4, &ecx, 4);
  89         memcpy(signature + 8, &edx, 4);
  90         signature[12] = 0;
  91
  92         if (strcmp(signature, "KVMKVMKVM") == 0)
  93                 return 1;
  94
  95         return 0;
  96 }
  97
  98 static inline unsigned int kvm_arch_para_features(void)
  99 {
 100         return cpuid_eax(KVM_CPUID_FEATURES);
 101 }
 102
 103 #endif
 104
 105 #endif