Add KVM support to QEMU

This patch adds very basic KVM support.  KVM is a kernel module for Linux that
allows userspace programs to make use of hardware virtualization support.  It
current supports x86 hardware virtualization using Intel VT-x or AMD-V.  It
also supports IA64 VT-i, PPC 440, and S390.

This patch only implements the bare minimum support to get a guest booting.  It
has very little impact the rest of QEMU and attempts to integrate nicely with
the rest of QEMU.

Even though this implementation is basic, it is significantly faster than TCG.
Booting and shutting down a Linux guest:

w/TCG:  1:32.36 elapsed  84% CPU

w/KVM:  0:31.14 elapsed  59% CPU

Right now, KVM is disabled by default and must be explicitly enabled with
 -enable-kvm.  We can enable it by default later when we have had better
testing.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5627 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 73 insertions, 0 deletions

diff --git a/target-i386/helper.c b/target-i386/helper.c
index bcf5e7f..4b8c503 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -29,6 +29,7 @@
 #include "exec-all.h"
 #include "svm.h"
 #include "qemu-common.h"
+#include "kvm.h"
 
 //#define DEBUG_MMU
 
@@ -115,6 +116,8 @@ CPUX86State *cpu_x86_init(const char *cpu_model)
 #ifdef USE_KQEMU
     kqemu_init(env);
 #endif
+    if (kvm_enabled())
+        kvm_init_vcpu(env);
     return env;
 }
 
@@ -1288,6 +1291,40 @@ target_phys_addr_t cpu_get_phys_page_debug(CPUState *env, target_ulong addr)
 }
 #endif /* !CONFIG_USER_ONLY */
 
+#if defined(CONFIG_KVM)
+static void host_cpuid(uint32_t function, uint32_t *eax, uint32_t *ebx,
+                       uint32_t *ecx, uint32_t *edx)
+{
+    uint32_t vec[4];
+
+#ifdef __x86_64__
+    asm volatile("cpuid"
+		 : "=a"(vec[0]), "=b"(vec[1]),
+		   "=c"(vec[2]), "=d"(vec[3])
+		 : "0"(function) : "cc");
+#else
+    asm volatile("pusha \n\t"
+		 "cpuid \n\t"
+		 "mov %%eax, 0(%1) \n\t"
+		 "mov %%ebx, 4(%1) \n\t"
+		 "mov %%ecx, 8(%1) \n\t"
+		 "mov %%edx, 12(%1) \n\t"
+		 "popa"
+		 : : "a"(function), "S"(vec)
+		 : "memory", "cc");
+#endif
+
+    if (eax)
+	*eax = vec[0];
+    if (ebx)
+	*ebx = vec[1];
+    if (ecx)
+	*ecx = vec[2];
+    if (edx)
+	*edx = vec[3];
+}
+#endif
+
 void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
                    uint32_t *eax, uint32_t *ebx,
                    uint32_t *ecx, uint32_t *edx)
@@ -1307,12 +1344,23 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
         *ebx = env->cpuid_vendor1;
         *edx = env->cpuid_vendor2;
         *ecx = env->cpuid_vendor3;
+
+        /* sysenter isn't supported on compatibility mode on AMD.  and syscall
+         * isn't supported in compatibility mode on Intel.  so advertise the
+         * actuall cpu, and say goodbye to migration between different vendors
+         * is you use compatibility mode. */
+        if (kvm_enabled())
+            host_cpuid(0, NULL, ebx, ecx, edx);
         break;
     case 1:
         *eax = env->cpuid_version;
         *ebx = (env->cpuid_apic_id << 24) | 8 << 8; /* CLFLUSH size in quad words, Linux wants it. */
         *ecx = env->cpuid_ext_features;
         *edx = env->cpuid_features;
+
+        /* "Hypervisor present" bit required for Microsoft SVVP */
+        if (kvm_enabled())
+            *ecx |= (1 << 31);
         break;
     case 2:
         /* cache info: needed for Pentium Pro compatibility */
@@ -1390,6 +1438,31 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
         *ebx = 0;
         *ecx = env->cpuid_ext3_features;
         *edx = env->cpuid_ext2_features;
+
+        if (kvm_enabled()) {
+            uint32_t h_eax, h_edx;
+
+            host_cpuid(0x80000001, &h_eax, NULL, NULL, &h_edx);
+
+            /* disable CPU features that the host does not support */
+
+            /* long mode */
+            if ((h_edx & 0x20000000) == 0 /* || !lm_capable_kernel */)
+                *edx &= ~0x20000000;
+            /* syscall */
+            if ((h_edx & 0x00000800) == 0)
+                *edx &= ~0x00000800;
+            /* nx */
+            if ((h_edx & 0x00100000) == 0)
+                *edx &= ~0x00100000;
+
+            /* disable CPU features that KVM cannot support */
+
+            /* svm */
+            *ecx &= ~4UL;
+            /* 3dnow */
+            *edx = ~0xc0000000;
+        }
         break;
     case 0x80000002:
     case 0x80000003: