1#ifndef __LINUX_KVM_PARA_H
2#define __LINUX_KVM_PARA_H
3
4/*
5 * Guest OS interface for KVM paravirtualization
6 *
7 * Note: this interface is totally experimental, and is certain to change
8 *       as we make progress.
9 */
10
11/*
12 * Per-VCPU descriptor area shared between guest and host. Writable to
13 * both guest and host. Registered with the host by the guest when
14 * a guest acknowledges paravirtual mode.
15 *
16 * NOTE: all addresses are guest-physical addresses (gpa), to make it
17 * easier for the hypervisor to map between the various addresses.
18 */
19struct kvm_vcpu_para_state {
20	/*
21	 * API version information for compatibility. If there's any support
22	 * mismatch (too old host trying to execute too new guest) then
23	 * the host will deny entry into paravirtual mode. Any other
24	 * combination (new host + old guest and new host + new guest)
25	 * is supposed to work - new host versions will support all old
26	 * guest API versions.
27	 */
28	u32 guest_version;
29	u32 host_version;
30	u32 size;
31	u32 ret;
32
33	/*
34	 * The address of the vm exit instruction (VMCALL or VMMCALL),
35	 * which the host will patch according to the CPU model the
36	 * VM runs on:
37	 */
38	u64 hypercall_gpa;
39
40} __attribute__ ((aligned(PAGE_SIZE)));
41
42#define KVM_PARA_API_VERSION 1
43
44/*
45 * This is used for an RDMSR's ECX parameter to probe for a KVM host.
46 * Hopefully no CPU vendor will use up this number. This is placed well
47 * out of way of the typical space occupied by CPU vendors' MSR indices,
48 * and we think (or at least hope) it wont be occupied in the future
49 * either.
50 */
51#define MSR_KVM_API_MAGIC 0x87655678
52
53#define KVM_EINVAL 1
54
55/*
56 * Hypercall calling convention:
57 *
58 * Each hypercall may have 0-6 parameters.
59 *
60 * 64-bit hypercall index is in RAX, goes from 0 to __NR_hypercalls-1
61 *
62 * 64-bit parameters 1-6 are in the standard gcc x86_64 calling convention
63 * order: RDI, RSI, RDX, RCX, R8, R9.
64 *
65 * 32-bit index is EBX, parameters are: EAX, ECX, EDX, ESI, EDI, EBP.
66 * (the first 3 are according to the gcc regparm calling convention)
67 *
68 * No registers are clobbered by the hypercall, except that the
69 * return value is in RAX.
70 */
71#define __NR_hypercalls			0
72
73#endif
74