tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
32static 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
41static 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
50static 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
60static 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
70static 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
81static 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
98static inline unsigned int kvm_arch_para_features(void)
99{
100 return cpuid_eax(KVM_CPUID_FEATURES);
101}
102
103#endif
104
105#endif