diff options
Diffstat (limited to 'include/linux/kvm_para.h')
| -rw-r--r-- | include/linux/kvm_para.h | 159 |
1 files changed, 98 insertions, 61 deletions
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h index 3b29256..cc5dfb4 100644 --- a/include/linux/kvm_para.h +++ b/include/linux/kvm_para.h @@ -1,73 +1,110 @@ #ifndef __LINUX_KVM_PARA_H #define __LINUX_KVM_PARA_H -/* - * Guest OS interface for KVM paravirtualization - * - * Note: this interface is totally experimental, and is certain to change - * as we make progress. +/* 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 -/* - * Per-VCPU descriptor area shared between guest and host. Writable to - * both guest and host. Registered with the host by the guest when - * a guest acknowledges paravirtual mode. - * - * NOTE: all addresses are guest-physical addresses (gpa), to make it - * easier for the hypervisor to map between the various addresses. - */ -struct kvm_vcpu_para_state { - /* - * API version information for compatibility. If there's any support - * mismatch (too old host trying to execute too new guest) then - * the host will deny entry into paravirtual mode. Any other - * combination (new host + old guest and new host + new guest) - * is supposed to work - new host versions will support all old - * guest API versions. - */ - u32 guest_version; - u32 host_version; - u32 size; - u32 ret; - - /* - * The address of the vm exit instruction (VMCALL or VMMCALL), - * which the host will patch according to the CPU model the - * VM runs on: - */ - u64 hypercall_gpa; - -} __attribute__ ((aligned(PAGE_SIZE))); - -#define KVM_PARA_API_VERSION 1 - -/* - * This is used for an RDMSR's ECX parameter to probe for a KVM host. - * Hopefully no CPU vendor will use up this number. This is placed well - * out of way of the typical space occupied by CPU vendors' MSR indices, - * and we think (or at least hope) it wont be occupied in the future - * either. +/* This CPUID returns a feature bitmap in eax. Before enabling a particular + * paravirtualization, the appropriate feature bit should be checked. */ -#define MSR_KVM_API_MAGIC 0x87655678 +#define KVM_CPUID_FEATURES 0x40000001 -#define KVM_EINVAL 1 +/* Return values for hypercalls */ +#define KVM_ENOSYS 1000 -/* - * Hypercall calling convention: - * - * Each hypercall may have 0-6 parameters. - * - * 64-bit hypercall index is in RAX, goes from 0 to __NR_hypercalls-1 - * - * 64-bit parameters 1-6 are in the standard gcc x86_64 calling convention - * order: RDI, RSI, RDX, RCX, R8, R9. - * - * 32-bit index is EBX, parameters are: EAX, ECX, EDX, ESI, EDI, EBP. - * (the first 3 are according to the gcc regparm calling convention) +#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. * - * No registers are clobbered by the hypercall, except that the - * return value is in RAX. + * 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. */ -#define __NR_hypercalls 0 + +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 int kvm_para_has_feature(unsigned int feature) +{ + if (cpuid_eax(KVM_CPUID_FEATURES) & (1UL << feature)) + return 1; + return 0; +} + +#endif #endif |