Add max vcpu IOCTL and support 64 vcpu

This commit tried to add ioctl HAX_IOCTL_CAP_MAX_VCPU that will return
the HAXM max vcpu support. Also, the switch case for hax device and vm
device add return -ENOSYS in the default case. Moreover, the max HAXM
supported vcpu value is updated from 16 to 64. Previously, HAXM doesn't
support IOCTL that would return the max vcpu value.

This issue is resolved by adding a new IOCTL HAX_IOCTL_CAP_MAX_VCPU that
will simply return HAX_MAX_VCPUS. (IOCTL naming credit to KVM)

This commit results in if QEMU calls this IOCTL, it will get the max
vcpu value HAXM driver supported and can then compare it with the QEMU
max value and smp value to determine whether the smp value is valid.

Signed-off-by: WangBowen <bowen.wang@intel.com>

core/include/config.h

@@ -66,7 +66,7 @@ struct config_t {
     int no_msr_pass_through;
 };
 
-#define HAX_MAX_VCPUS 16
+#define HAX_MAX_VCPUS 64
 
 #ifdef HAX_PLATFORM_NETBSD
 // TODO: Handle 64 VMs

include/darwin/hax_interface_mac.h

@@ -41,6 +41,7 @@
 #define HAX_IOCTL_DESTROY_VM _IOW(0, 0x22, uint32_t)
 #define HAX_IOCTL_CAPABILITY _IOR(0, 0x23, struct hax_capabilityinfo)
 #define HAX_IOCTL_SET_MEMLIMIT _IOWR(0, 0x24, struct hax_set_memlimit)
+#define HAX_IOCTL_CAP_MAX_VCPU _IOR(0, 0x25, uint32_t)
 
 // Only for backward compatibility with old Qemu.
 #define HAX_VM_IOCTL_VCPU_CREATE_ORIG _IOR(0, 0x80, int)

include/linux/hax_interface_linux.h

@@ -42,6 +42,7 @@
 #define HAX_IOCTL_DESTROY_VM _IOW(0, 0x22, uint32_t)
 #define HAX_IOCTL_CAPABILITY _IOR(0, 0x23, struct hax_capabilityinfo)
 #define HAX_IOCTL_SET_MEMLIMIT _IOWR(0, 0x24, struct hax_set_memlimit)
+#define HAX_IOCTL_CAP_MAX_VCPU _IOR(0, 0x25, uint32_t)
 
 // Only for backward compatibility with old Qemu.
 #define HAX_VM_IOCTL_VCPU_CREATE_ORIG _IOR(0, 0x80, int)

include/netbsd/hax_interface_netbsd.h

@@ -45,6 +45,7 @@
 #define HAX_IOCTL_DESTROY_VM _IOW(0, 0x22, uint32_t)
 #define HAX_IOCTL_CAPABILITY _IOR(0, 0x23, struct hax_capabilityinfo)
 #define HAX_IOCTL_SET_MEMLIMIT _IOWR(0, 0x24, struct hax_set_memlimit)
+#define HAX_IOCTL_CAP_MAX_VCPU _IOR(0, 0x25, uint32_t)
 
 // Only for backward compatibility with old Qemu.
 #define HAX_VM_IOCTL_VCPU_CREATE_ORIG _IOR(0, 0x80, int)

platforms/darwin/com_intel_hax_ui.c

@@ -596,7 +596,10 @@ static int hax_ioctl(dev_t dev, u_long cmd, caddr_t data, int flag,
             *((uint32_t *)data) = vm_id;
             break;
         }
-
+        case HAX_IOCTL_CAP_MAX_VCPU: {
+            *((uint32_t *)data) = HAX_MAX_VCPUS;
+            break;
+        }
         default: {
             handle_unknown_ioctl(dev, cmd, p);
             ret = -ENOSYS;

platforms/linux/components.c

@@ -653,6 +653,7 @@ static long hax_vm_ioctl(struct file *filp, unsigned int cmd,
     default:
         // TODO: Print information about the process that sent the ioctl.
         hax_log(HAX_LOGE, "Unknown VM IOCTL 0x%lx\n", cmd);
+        ret = -ENOSYS;
         break;
     }
     hax_put_vm(cvm);

platforms/linux/hax_entry.c

@@ -39,6 +39,7 @@
 #include "../../include/hax_interface.h"
 #include "../../include/hax_release_ver.h"
 #include "../../core/include/hax_core_interface.h"
+#include "../../core/include/config.h"
 
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Kryptos Logic");
@@ -106,7 +107,18 @@ static long hax_dev_ioctl(struct file *filp, unsigned int cmd,
             return -EFAULT;
         break;
     }
+    case HAX_IOCTL_CAP_MAX_VCPU: {
+        int max_vcpu = HAX_MAX_VCPUS;
+
+        if (copy_to_user(argp, &max_vcpu, sizeof(max_vcpu)))
+            return -EFAULT;
+
+        break;
+    }
+
     default:
+        hax_log(HAX_LOGE, "Invalid HAX IOCTL 0x%lx\n", cmd);
+        ret = -ENOSYS;
         break;
     }
     return ret;

platforms/netbsd/hax_entry_hax.c

@@ -116,6 +116,10 @@ int hax_ioctl(dev_t self __unused, u_long cmd, void *data, int flag,
         *((uint32_t *)data) = vm_id;
         break;
     }
+    case HAX_IOCTL_CAP_MAX_VCPU: {
+        *((uint32_t *)data) = HAX_MAX_VCPUS;
+        break;
+    }
     default:
         hax_log(HAX_LOGE, "Unknown ioctl %#lx, pid=%d ('%s')\n", cmd,
                 l->l_proc->p_pid, l->l_proc->p_comm);

platforms/windows/hax_entry.c

@@ -35,6 +35,7 @@
 #include <string.h>
 
 #include "hax_win.h"
+#include "../../core/include/config.h"
 
 // vcpu.h
 int vcpu_takeoff(struct vcpu_t *vcpu);
@@ -714,6 +715,16 @@ NTSTATUS HaxDeviceControl(PDEVICE_OBJECT DeviceObject,
             infret = sizeof(uint32_t);
             ret = STATUS_SUCCESS;
             break;
+        case HAX_IOCTL_CAP_MAX_VCPU:
+            if (outBufLength < sizeof(uint32_t)) {
+                Irp->IoStatus.Information = 0;
+                ret = STATUS_BUFFER_TOO_SMALL;
+                goto done;
+            }
+            *((uint32_t *)outBuf) = HAX_MAX_VCPUS;
+            infret = sizeof(uint32_t);
+            ret = STATUS_SUCCESS;
+            break;
         default:
             ret = STATUS_INVALID_DEVICE_REQUEST;
             hax_log(HAX_LOGE, "Invalid hax ioctl %x\n",

platforms/windows/hax_entry.h

@@ -120,6 +120,8 @@ extern PDRIVER_OBJECT HaxDriverObject;
         CTL_CODE(HAX_DEVICE_TYPE, 0x910, METHOD_BUFFERED, FILE_ANY_ACCESS)
 #define HAX_IOCTL_SET_MEMLIMIT \
         CTL_CODE(HAX_DEVICE_TYPE, 0x911, METHOD_BUFFERED, FILE_ANY_ACCESS)
+#define HAX_IOCTL_CAP_MAX_VCPU \
+        CTL_CODE(HAX_DEVICE_TYPE, 0x917, METHOD_BUFFERED, FILE_ANY_ACCESS)
 
 #define HAX_VM_IOCTL_VCPU_CREATE \
         CTL_CODE(HAX_DEVICE_TYPE, 0x902, METHOD_BUFFERED, FILE_ANY_ACCESS)