KVM: Per-architecture hypercall definitions

Currently kvm provides hypercalls only for x86* architectures. To
provide hypercall infrastructure for other kvm architectures I split
kvm_para.h into a generic header file and architecture specific
definitions.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 105 insertions, 0 deletions

diff --git a/include/asm-x86/kvm_para.h b/include/asm-x86/kvm_para.h
new file mode 100644
index 000000000000..c6f3fd8d8c53
--- /dev/null
+++ b/include/asm-x86/kvm_para.h
@@ -0,0 +1,105 @@
+#ifndef __X86_KVM_PARA_H
+#define __X86_KVM_PARA_H
+
+/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
+ * should be used to determine that a VM is running under KVM.
+ */
+#define KVM_CPUID_SIGNATURE     0x40000000
+
+/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
+ * paravirtualization, the appropriate feature bit should be checked.
+ */
+#define KVM_CPUID_FEATURES      0x40000001
+
+#ifdef __KERNEL__
+#include <asm/processor.h>
+
+/* This instruction is vmcall.  On non-VT architectures, it will generate a
+ * trap that we will then rewrite to the appropriate instruction.
+ */
+#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
+
+/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
+ * instruction.  The hypervisor may replace it with something else but only the
+ * instructions are guaranteed to be supported.
+ *
+ * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
+ * The hypercall number should be placed in rax and the return value will be
+ * placed in rax.  No other registers will be clobbered unless explicited
+ * noted by the particular hypercall.
+ */
+
+static inline long kvm_hypercall0(unsigned int nr)
+{
+        long ret;
+        asm volatile(KVM_HYPERCALL
+                     : "=a"(ret)
+                     : "a"(nr));
+        return ret;
+}
+
+static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
+{
+        long ret;
+        asm volatile(KVM_HYPERCALL
+                     : "=a"(ret)
+                     : "a"(nr), "b"(p1));
+        return ret;
+}
+
+static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
+                                  unsigned long p2)
+{
+        long ret;
+        asm volatile(KVM_HYPERCALL
+                     : "=a"(ret)
+                     : "a"(nr), "b"(p1), "c"(p2));
+        return ret;
+}
+
+static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
+                                  unsigned long p2, unsigned long p3)
+{
+        long ret;
+        asm volatile(KVM_HYPERCALL
+                     : "=a"(ret)
+                     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
+        return ret;
+}
+
+static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
+                                  unsigned long p2, unsigned long p3,
+                                  unsigned long p4)
+{
+        long ret;
+        asm volatile(KVM_HYPERCALL
+                     : "=a"(ret)
+                     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
+        return ret;
+}
+
+static inline int kvm_para_available(void)
+{
+        unsigned int eax, ebx, ecx, edx;
+        char signature[13];
+
+        cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
+        memcpy(signature + 0, &ebx, 4);
+        memcpy(signature + 4, &ecx, 4);
+        memcpy(signature + 8, &edx, 4);
+        signature[12] = 0;
+
+        if (strcmp(signature, "KVMKVMKVM") == 0)
+                return 1;
+
+        return 0;
+}
+
+static inline unsigned int kvm_arch_para_features(void)
+{
+        return cpuid_eax(KVM_CPUID_FEATURES);
+}
+
+#endif
+
+#endif