include/linux/kvm_para.h

   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  */
  19 struct 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