Palacios Public Git Repository

To checkout Palacios execute

  git clone http://v3vee.org/palacios/palacios.web/palacios.git
This will give you the master branch. You probably want the devel branch or one of the release branches. To switch to the devel branch, simply execute
  cd palacios
  git checkout --track -b devel origin/devel
The other branches are similar.


Addition of basic multiboot functionality plus refactor of HVM
[palacios.git] / palacios / src / palacios / vmm_hvm.c
index 4225d28..edff2fd 100644 (file)
 #include <palacios/vmm_emulator.h>
 #include <palacios/vm_guest.h>
 #include <palacios/vmm_debug.h>
+#include <palacios/vmm_hypercall.h>
 
 #include <palacios/vmm_xml.h>
 
-#include <stdio.h>
-#include <stdlib.h>
+#include <palacios/vm_guest_mem.h>
+
+#include <palacios/vmm_debug.h>
+
 
 /*
 
 #define PrintDebug(fmt, args...)
 #endif
 
+
+// if set, we will map the first 1 GB of memory using a 3 level
+// hierarchy, for compatibility with Nautilus out of the box.
+// Otherwise we will map the first 512 GB using a 2 level
+// hieratchy
+#define HVM_MAP_1G_2M 1
+
 int v3_init_hvm()
 {
     PrintDebug(VM_NONE,VCORE_NONE, "hvm: init\n");
@@ -78,6 +88,21 @@ int v3_deinit_hvm()
 }
 
 
+static int hvm_hcall_handler(struct guest_info * core , hcall_id_t hcall_id, void * priv_data)
+{
+    uint64_t c;
+
+    rdtscll(c);
+
+
+    V3_Print(core->vm_info,core, "hvm: received hypercall %x  rax=%llx rbx=%llx rcx=%llx at cycle count %llu (%llu cycles since last boot start) num_exits=%llu since initial boot\n",
+            hcall_id, core->vm_regs.rax, core->vm_regs.rbx, core->vm_regs.rcx, c, c-core->hvm_state.last_boot_start, core->num_exits);
+    v3_print_core_telemetry(core);
+    //    v3_print_guest_state(core);
+
+    return 0;
+}
+
 #define CEIL_DIV(x,y) (((x)/(y)) + !!((x)%(y)))
 
 int v3_init_hvm_vm(struct v3_vm_info *vm, struct v3_xml *config)
@@ -88,7 +113,7 @@ int v3_init_hvm_vm(struct v3_vm_info *vm, struct v3_xml *config)
     char *enable;
     char *ros_cores;
     char *ros_mem;
-    char *hrt_file_id;
+    char *hrt_file_id=0;
 
     PrintDebug(vm, VCORE_NONE, "hvm: vm init\n");
 
@@ -146,6 +171,12 @@ int v3_init_hvm_vm(struct v3_vm_info *vm, struct v3_xml *config)
        return -1;
     }
 
+    if (v3_register_hypercall(vm, HVM_HCALL, 
+                             hvm_hcall_handler, 0)) { 
+       PrintError(vm,VCORE_NONE, "hvm: cannot register hypercall....\n");
+       return -1;
+    }
+
     // XXX sanity check config here
 
     vm->hvm_state.is_hvm=1;
@@ -168,9 +199,12 @@ int v3_init_hvm_vm(struct v3_vm_info *vm, struct v3_xml *config)
     
 }
 
+
 int v3_deinit_hvm_vm(struct v3_vm_info *vm)
 {
-    PrintDebug(vm, VCORE_NONE, "hvm: HVM deinit\n");
+    PrintDebug(vm, VCORE_NONE, "hvm: HVM VM deinit\n");
+
+    v3_remove_hypercall(vm,HVM_HCALL);
 
     return 0;
 }
@@ -188,6 +222,8 @@ int v3_init_hvm_core(struct guest_info *core)
 
 int v3_deinit_hvm_core(struct guest_info *core)
 {
+    PrintDebug(core->vm_info, VCORE_NONE, "hvm: HVM core deinit\n");
+
     return 0;
 }
 
@@ -295,5 +331,826 @@ void     v3_hvm_find_apics_seen_by_core(struct guest_info *core, struct v3_vm_in
        }
     }
 }
+
+#define MAX(x,y) ((x)>(y)?(x):(y))
+#define MIN(x,y) ((x)<(y)?(x):(y))
+
+#ifdef HVM_MAP_1G_2M
+#define BOOT_STATE_END_ADDR (MIN(vm->mem_size,0x40000000ULL))
+#else
+#define BOOT_STATE_END_ADDR (MIN(vm->mem_size,0x800000000ULL))
+#endif
+
+static void get_null_int_handler_loc(struct v3_vm_info *vm, void **base, uint64_t *limit)
+{
+    *base = (void*) PAGE_ADDR(BOOT_STATE_END_ADDR - PAGE_SIZE);
+    *limit = PAGE_SIZE;
+}
+
+extern v3_cpu_arch_t v3_mach_type;
+
+extern void *v3_hvm_svm_null_int_handler_start;
+extern void *v3_hvm_svm_null_int_handler_end;
+extern void *v3_hvm_vmx_null_int_handler_start;
+extern void *v3_hvm_vmx_null_int_handler_end;
+
+static void write_null_int_handler(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t limit;
+    void *data;
+    uint64_t len;
+
+    get_null_int_handler_loc(vm,&base,&limit);
+
+    switch (v3_mach_type) {
+#ifdef V3_CONFIG_SVM
+       case V3_SVM_CPU:
+       case V3_SVM_REV3_CPU:
+           data = (void*) &v3_hvm_svm_null_int_handler_start;
+           len = (void*) &v3_hvm_svm_null_int_handler_end - data;
+           break;
+#endif
+#if V3_CONFIG_VMX
+       case V3_VMX_CPU:
+       case V3_VMX_EPT_CPU:
+       case V3_VMX_EPT_UG_CPU:
+           data = (void*) &v3_hvm_vmx_null_int_handler_start;
+           len = (void*) &v3_hvm_vmx_null_int_handler_end - data;
+           break;
+#endif
+       default:
+           PrintError(vm,VCORE_NONE,"hvm: cannot determine CPU type to select null interrupt handler...\n");
+           data = 0;
+           len = 0;
+    }
+
+    if (data) {
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base),len,(uint8_t*)data);
+    }
+
+    PrintDebug(vm,VCORE_NONE,"hvm: wrote null interrupt handler at %p (%llu bytes)\n",base,len);
+}
+
+
+static void get_idt_loc(struct v3_vm_info *vm, void **base, uint64_t *limit)
+{
+    *base = (void*) PAGE_ADDR(BOOT_STATE_END_ADDR - 2 * PAGE_SIZE);
+    *limit = 16*256;
+}
+
+// default IDT entries (int and trap gates)
+//
+// Format is 16 bytes long:
+//   16 offsetlo   => 0
+//   16 selector   => (target code selector) => 0x8 // entry 1 of GDT
+//    3 ist        => (stack) = 0 => current stack
+//    5 reserved   => 0
+//    4 type       => 0xe=>INT, 0xf=>TRAP 
+//    1 reserved   => 0
+//    2 dpl        => 0
+//    1 present    => 1
+//   16 offsetmid  => 0
+//   32 offsethigh => 0   (total is a 64 bit offset)
+//   32 reserved   => 0
+//
+// 00 00 | 08 00 | 00 | 8[typenybble] | offsetmid | offsethigh | reserved
+// 
+// Note little endian
+//
+static uint64_t idt64_trap_gate_entry_mask[2] = {  0x00008f0000080000, 0x0 } ;
+static uint64_t idt64_int_gate_entry_mask[2] =  { 0x00008e0000080000, 0x0 };
+
+static void write_idt(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t limit;
+    void *handler;
+    uint64_t handler_len;
+    int i;
+    uint64_t trap_gate[2];
+    uint64_t int_gate[2];
+
+    get_idt_loc(vm,&base,&limit);
+
+    get_null_int_handler_loc(vm,&handler,&handler_len);
+
+    memcpy(trap_gate,idt64_trap_gate_entry_mask,16);
+    memcpy(int_gate,idt64_int_gate_entry_mask,16);
+
+    if (handler) {
+       // update the entries for the handler location
+       uint8_t *mask;
+       uint8_t *hand;
+       
+       hand = (uint8_t*) &handler;
+
+       mask = (uint8_t *)trap_gate;
+       memcpy(&(mask[0]),&(hand[0]),2); // offset low
+       memcpy(&(mask[6]),&(hand[2]),2); // offset med
+       memcpy(&(mask[8]),&(hand[4]),4); // offset high
+
+       mask = (uint8_t *)int_gate;
+       memcpy(&(mask[0]),&(hand[0]),2); // offset low
+       memcpy(&(mask[6]),&(hand[2]),2); // offset med
+       memcpy(&(mask[8]),&(hand[4]),4); // offset high
+
+       PrintDebug(vm,VCORE_NONE,"hvm: Adding default null trap and int gates\n");
+    }
+
+    for (i=0;i<32;i++) { 
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+i*16),16,(uint8_t*)trap_gate);
+    }
+
+    for (i=32;i<256;i++) { 
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+i*16),16,(uint8_t*)int_gate);
+    }
+
+    PrintDebug(vm,VCORE_NONE,"hvm: wrote IDT at %p\n",base);
+}
+
+
+
+static void get_gdt_loc(struct v3_vm_info *vm, void **base, uint64_t *limit)
+{
+    *base = (void*)PAGE_ADDR(BOOT_STATE_END_ADDR - 3 * PAGE_SIZE);
+    *limit = 8*3;
+}
+
+static uint64_t gdt64[3] = {
+    0x0000000000000000, /* null */
+    0x00a09a0000000000, /* code (note lme bit) */
+    0x00a0920000000000, /* data (most entries don't matter) */
+};
+
+static void write_gdt(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t limit;
+
+    get_gdt_loc(vm,&base,&limit);
+    v3_write_gpa_memory(&vm->cores[0],(addr_t)base,limit,(uint8_t*) gdt64);
+
+    PrintDebug(vm,VCORE_NONE,"hvm: wrote GDT at %p\n",base);
+}
+
+
+
+static void get_tss_loc(struct v3_vm_info *vm, void **base, uint64_t *limit)
+{
+    *base = (void*)PAGE_ADDR(BOOT_STATE_END_ADDR - 4 * PAGE_SIZE);
+    *limit = PAGE_SIZE;
+}
+
+static uint64_t tss_data=0x0;
+
+static void write_tss(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t limit;
+    int i;
+
+    get_tss_loc(vm,&base,&limit);
+    for (i=0;i<limit/8;i++) {
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+8*i),8,(uint8_t*) &tss_data);
+    }
+
+    PrintDebug(vm,VCORE_NONE,"hvm: wrote TSS at %p\n",base);
+}
+
+/*
+  PTS MAP FIRST 512 GB identity mapped: 
+  1 second level
+     512 entries
+  1 top level
+     1 entries
+
+OR
+  
+  PTS MAP FIRST 1 GB identity mapped:
+  1 third level
+    512 entries
+  1 second level
+    1 entries
+  1 top level
+    1 entries
+*/
+
+static void get_pt_loc(struct v3_vm_info *vm, void **base, uint64_t *limit)
+{
+#ifdef HVM_MAP_1G_2M
+    *base = (void*)PAGE_ADDR(BOOT_STATE_END_ADDR-(5+2)*PAGE_SIZE);
+    *limit =  3*PAGE_SIZE;
+#else
+    *base = (void*)PAGE_ADDR(BOOT_STATE_END_ADDR-(5+1)*PAGE_SIZE);
+    *limit =  2*PAGE_SIZE;
+#endif
+}
+
+#ifndef HVM_MAP_1G_2M
+static void write_pt_2level_512GB(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t size;
+    struct pml4e64 pml4e;
+    struct pdpe64 pdpe;
+    uint64_t i;
+
+    get_pt_loc(vm,&base, &size);
+    if (size!=2*PAGE_SIZE) { 
+       PrintError(vm,VCORE_NONE,"Cannot support pt request, defaulting\n");
+    }
+
+    if (vm->mem_size > 0x800000000ULL) { 
+       PrintError(vm,VCORE_NONE, "VM has more than 512 GB\n");
+    }
+
+    memset(&pdpe,0,sizeof(pdpe));
+    pdpe.present=1;
+    pdpe.writable=1;
+    pdpe.large_page=1;
+    
+    for (i=0;i<512;i++) {
+       pdpe.pd_base_addr = i*0x40000;  // 0x4000 = 256K pages = 1 GB
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+PAGE_SIZE+i*sizeof(pdpe)),sizeof(pdpe),(uint8_t*)&pdpe);
+    }
+
+    memset(&pml4e,0,sizeof(pml4e));
+    pml4e.present=1;
+    pml4e.writable=1;
+    pml4e.pdp_base_addr = PAGE_BASE_ADDR((addr_t)(base+PAGE_SIZE));
+
+    v3_write_gpa_memory(&vm->cores[0],(addr_t)base,sizeof(pml4e),(uint8_t*)&pml4e);    
+
+    for (i=1;i<512;i++) {
+       pml4e.present=0;
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+i*sizeof(pml4e)),sizeof(pml4e),(uint8_t*)&pml4e);
+    }
+
+    PrintDebug(vm,VCORE_NONE,"hvm: Wrote page tables (1 PML4, 1 PDPE) at %p (512 GB mapped)\n",base);
+}
+
+#else 
+
+static void write_pt_3level_1GB(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t size;
+    struct pml4e64 pml4e;
+    struct pdpe64 pdpe;
+    struct pde64 pde;
+
+    uint64_t i;
+
+    get_pt_loc(vm,&base, &size);
+    if (size!=3*PAGE_SIZE) { 
+       PrintError(vm,VCORE_NONE,"Cannot support pt request, defaulting\n");
+    }
+
+    if (vm->mem_size > 0x40000000ULL) { 
+       PrintError(vm,VCORE_NONE, "VM has more than 1 GB\n");
+    }
+
+    memset(&pde,0,sizeof(pde));
+    pde.present=1;
+    pde.writable=1;
+    pde.large_page=1;
+    
+    for (i=0;i<512;i++) {
+       pde.pt_base_addr = i*0x200;  // 0x200 = 512 pages = 2 MB
+       v3_write_gpa_memory(&vm->cores[0],
+                           (addr_t)(base+2*PAGE_SIZE+i*sizeof(pde)),
+                           sizeof(pde),(uint8_t*)&pde);
+    }
+
+    memset(&pdpe,0,sizeof(pdpe));
+    pdpe.present=1;
+    pdpe.writable=1;
+    pdpe.large_page=0;
+
+    pdpe.pd_base_addr = PAGE_BASE_ADDR((addr_t)(base+2*PAGE_SIZE));
+
+    v3_write_gpa_memory(&vm->cores[0],(addr_t)base+PAGE_SIZE,sizeof(pdpe),(uint8_t*)&pdpe);    
+    
+    for (i=1;i<512;i++) {
+       pdpe.present = 0; 
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+PAGE_SIZE+i*sizeof(pdpe)),sizeof(pdpe),(uint8_t*)&pdpe);
+    }
+
+    memset(&pml4e,0,sizeof(pml4e));
+    pml4e.present=1;
+    pml4e.writable=1;
+    pml4e.pdp_base_addr = PAGE_BASE_ADDR((addr_t)(base+PAGE_SIZE));
+
+    v3_write_gpa_memory(&vm->cores[0],(addr_t)base,sizeof(pml4e),(uint8_t*)&pml4e);    
+
+    for (i=1;i<512;i++) {
+       pml4e.present=0;
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+i*sizeof(pml4e)),sizeof(pml4e),(uint8_t*)&pml4e);
+    }
+
+    PrintDebug(vm,VCORE_NONE,"hvm: Wrote page tables (1 PML4, 1 PDPE, 1 PDP) at %p (1 GB mapped)\n",base);
+}
+
+#endif
+
+static void write_pt(struct v3_vm_info *vm)
+{
+#ifdef HVM_MAP_1G_2M
+    write_pt_3level_1GB(vm);
+#else
+    write_pt_2level_512GB(vm);
+#endif
+}
+
+static void get_bp_loc(struct v3_vm_info *vm, void **base, uint64_t *limit)
+{
+#ifdef HVM_MAP_1G_2M
+    *base = (void*) PAGE_ADDR(BOOT_STATE_END_ADDR-(6+2)*PAGE_SIZE);
+#else
+    *base = (void*) PAGE_ADDR(BOOT_STATE_END_ADDR-(6+1)*PAGE_SIZE);
+#endif
+    *limit =  PAGE_SIZE;
+}
+
+static void write_bp(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t limit;
+    uint64_t data=-1;
+    int i;
+
+    get_bp_loc(vm,&base,&limit);
+    
+    for (i=0;i<limit/8;i++) { 
+       v3_write_gpa_memory(&vm->cores[0],(addr_t)(base+i*8),8,(uint8_t*)&data);
+    }
+
+    PrintDebug(vm,VCORE_NONE,"hvm: wrote boundary page at %p\n", base);
+    
+}
+
+#define MIN_STACK (4096*4)
+
+
+static void get_hrt_loc(struct v3_vm_info *vm, void **base, uint64_t *limit)
+{
+    void *bp_base;
+    uint64_t bp_limit;
+    
+    get_bp_loc(vm,&bp_base,&bp_limit);
+    
+    // assume at least a minimal stack
+
+    bp_base-=MIN_STACK;
+
+    *base = (void*)PAGE_ADDR(vm->hvm_state.first_hrt_gpa);
+
+    if (bp_base < *base+PAGE_SIZE) { 
+       PrintError(vm,VCORE_NONE,"hvm: HRT stack colides with HRT\n");
+    }
+
+    *limit = bp_base - *base;
+}
+
+
+#define ERROR(fmt, args...) PrintError(VM_NONE,VCORE_NONE,"hvm: " fmt,##args)
+#define INFO(fmt, args...) PrintDebug(VM_NONE,VCORE_NONE,"hvm: " fmt,##args)
+
+#define ELF_MAGIC    0x464c457f
+#define MB2_MAGIC    0xe85250d6
+
+#define MB2_INFO_MAGIC    0x36d76289
+
+static int is_elf(uint8_t *data, uint64_t size)
+{
+    if (*((uint32_t*)data)==ELF_MAGIC) {
+       return 1;
+    } else { 
+       return 0;
+    }
+}
+
+static mb_header_t *find_mb_header(uint8_t *data, uint64_t size)
+{
+    uint64_t limit = size > 32768 ? 32768 : size;
+    uint64_t i;
+
+    // Scan for the .boot magic cookie
+    // must be in first 32K, assume 4 byte aligned
+    for (i=0;i<limit;i+=4) { 
+       if (*((uint32_t*)&data[i])==MB2_MAGIC) {
+           INFO("Found multiboot header at offset 0x%llx\n",i);
+           return (mb_header_t *) &data[i];
+       }
+    }
+    return 0;
+}
+
+
+// 
+// BROKEN - THIS DOES NOT DO WHAT YOU THINK
+//
+static int setup_elf(struct v3_vm_info *vm, void *base, uint64_t limit)
+{
+    v3_write_gpa_memory(&vm->cores[0],(addr_t)base,vm->hvm_state.hrt_file->size,vm->hvm_state.hrt_file->data);
+
+    vm->hvm_state.hrt_entry_addr = (uint64_t) (base+0x40);
+
+    PrintDebug(vm,VCORE_NONE,"hvm: wrote HRT ELF %s at %p\n", vm->hvm_state.hrt_file->tag,base);
+    PrintDebug(vm,VCORE_NONE,"hvm: set ELF entry to %p and hoping for the best...\n", (void*) vm->hvm_state.hrt_entry_addr);
+    
+    vm->hvm_state.hrt_type = HRT_ELF64;
+
+    return 0;
+
+}
+
+static int setup_mb_kernel(struct v3_vm_info *vm, void *base, uint64_t limit)
+{
+    mb_data_t mb;
+    uint32_t offset;
+
+
+    // FIX USING GENERIC TOOLS
+
+    if (v3_parse_multiboot_header(vm->hvm_state.hrt_file,&mb)) { 
+       PrintError(vm,VCORE_NONE, "hvm: failed to parse multiboot kernel header\n");
+       return -1;
+    }
+
+    if (!mb.addr || !mb.entry) { 
+       PrintError(vm,VCORE_NONE, "hvm: kernel is missing address or entry point\n");
+       return -1;
+    }
+
+    if (((void*)(uint64_t)(mb.addr->header_addr) < base ) ||
+       ((void*)(uint64_t)(mb.addr->load_end_addr) > base+limit) ||
+       ((void*)(uint64_t)(mb.addr->bss_end_addr) > base+limit)) { 
+       PrintError(vm,VCORE_NONE, "hvm: kernel is not within the allowed portion of HVM\n");
+       return -1;
+    }
+
+    offset = mb.addr->load_addr - mb.addr->header_addr;
+
+    // Skip the ELF header - assume 1 page... weird.... 
+    v3_write_gpa_memory(&vm->cores[0],
+                       (addr_t)(mb.addr->load_addr),
+                       vm->hvm_state.hrt_file->size-PAGE_SIZE-offset,
+                       vm->hvm_state.hrt_file->data+PAGE_SIZE+offset);
+
+       
+    // vm->hvm_state.hrt_entry_addr = (uint64_t) mb.entry->entry_addr + PAGE_SIZE; //HACK PAD
+
+    vm->hvm_state.hrt_entry_addr = (uint64_t) mb.entry->entry_addr;
+    
+    vm->hvm_state.hrt_type = HRT_MBOOT64;
+
+    PrintDebug(vm,VCORE_NONE,
+              "hvm: wrote 0x%llx bytes starting at offset 0x%llx to %p; set entry to %p\n",
+              (uint64_t) vm->hvm_state.hrt_file->size-PAGE_SIZE-offset,
+              (uint64_t) PAGE_SIZE+offset,
+              (void*)(addr_t)(mb.addr->load_addr),
+              (void*) vm->hvm_state.hrt_entry_addr);
+    return 0;
+
+}
+
+
+static int setup_hrt(struct v3_vm_info *vm)
+{
+    void *base;
+    uint64_t limit;
+
+    get_hrt_loc(vm,&base,&limit);
+
+    if (vm->hvm_state.hrt_file->size > limit) { 
+       PrintError(vm,VCORE_NONE,"hvm: Cannot map HRT because it is too big (%llu bytes, but only have %llu space\n", vm->hvm_state.hrt_file->size, (uint64_t)limit);
+       return -1;
+    }
+
+    if (!is_elf(vm->hvm_state.hrt_file->data,vm->hvm_state.hrt_file->size)) { 
+       PrintError(vm,VCORE_NONE,"hvm: supplied HRT is not an ELF but we are going to act like it is!\n");
+       if (setup_elf(vm,base,limit)) {
+           PrintError(vm,VCORE_NONE,"hvm: Fake ELF setup failed\n");
+           return -1;
+       }
+       vm->hvm_state.hrt_type=HRT_BLOB;
+    } else {
+       if (find_mb_header(vm->hvm_state.hrt_file->data,vm->hvm_state.hrt_file->size)) { 
+           PrintDebug(vm,VCORE_NONE,"hvm: appears to be a multiboot kernel\n");
+           if (setup_mb_kernel(vm,base,limit)) { 
+               PrintError(vm,VCORE_NONE,"hvm: multiboot kernel setup failed\n");
+               return -1;
+           } 
+       } else {
+           PrintDebug(vm,VCORE_NONE,"hvm: supplied HRT is an ELF\n");
+           if (setup_elf(vm,base,limit)) {
+               PrintError(vm,VCORE_NONE,"hvm: Fake ELF setup failed\n");
+               return -1;
+           }
+       }
+    }
+
+    return 0;
+}
+
+
+       
+
+/*
+  GPA layout:
+
+  HRT
+  ---
+  ROS
+
+  We do not touch the ROS portion of the address space.
+  The HRT portion looks like:
+
+  INT_HANDLER (1 page - page aligned)
+  IDT (1 page - page aligned)
+  GDT (1 page - page aligned)
+  TSS (1 page - page asligned)
+  PAGETABLES  (identy map of first N GB)
+     ROOT PT first, followed by 2nd level, etc.
+     Currently PML4 followed by 1 PDPE for 512 GB of mapping
+  BOUNDARY PAGE (all 0xff - avoid smashing page tables in case we keep going...)
+  (stack - we will push machine description)
+  ...
+  HRT (as many pages as needed, page-aligned, starting at first HRT address)
+  ---
+  ROS
+      
+*/
+
+
+int v3_setup_hvm_vm_for_boot(struct v3_vm_info *vm)
+{
+    if (!vm->hvm_state.is_hvm) { 
+       PrintDebug(vm,VCORE_NONE,"hvm: skipping HVM setup for boot as this is not an HVM\n");
+       return 0;
+    }
+
+    PrintDebug(vm,VCORE_NONE,"hvm: setup of HVM memory begins\n");
+
+    write_null_int_handler(vm);
+    write_idt(vm);
+    write_gdt(vm);
+    write_tss(vm);
+
+    write_pt(vm);
+
+    write_bp(vm);
+    
+    if (setup_hrt(vm)) {
+       PrintError(vm,VCORE_NONE,"hvm: failed to setup HRT\n");
+       return -1;
+    } 
+
+
+    PrintDebug(vm,VCORE_NONE,"hvm: setup of HVM memory done\n");
+
+    return 0;
+}
+
+/*
+  On entry:
+
+   IDTR points to stub IDT
+   GDTR points to stub GDT
+   TS   points to stub TSS
+   CR3 points to root page table
+   CR0 has PE and PG
+   EFER has LME AND LMA
+   RSP is TOS (looks like a call)
+       INFO                     <= RDI
+       0 (fake return address)  <= RSP
+       
+   RIP is entry point to HRT
+   RDI points to machine info on stack
+
+   Other regs are zeroed
+
+   shadow/nested paging state reset for long mode
+
+*/
+int v3_setup_hvm_hrt_core_for_boot(struct guest_info *core)
+{
+    void *base;
+    uint64_t limit;
+
+    rdtscll(core->hvm_state.last_boot_start);
+
+    if (!core->hvm_state.is_hrt) { 
+       PrintDebug(core->vm_info,core,"hvm: skipping HRT setup for core %u as it is not an HRT core\n", core->vcpu_id);
+       return 0;
+    }
+
+    PrintDebug(core->vm_info, core, "hvm: setting up HRT core (%u) for boot\n", core->vcpu_id);
+
+    
+    memset(&core->vm_regs,0,sizeof(core->vm_regs));
+    memset(&core->ctrl_regs,0,sizeof(core->ctrl_regs));
+    memset(&core->dbg_regs,0,sizeof(core->dbg_regs));
+    memset(&core->segments,0,sizeof(core->segments));    
+    memset(&core->msrs,0,sizeof(core->msrs));    
+    memset(&core->fp_state,0,sizeof(core->fp_state));    
+
+    // We are in long mode with virtual memory and we want
+    // to start immediatley
+    core->cpl = 0; // we are going right into the kernel
+    core->cpu_mode = LONG;
+    core->mem_mode = VIRTUAL_MEM; 
+    core->core_run_state = CORE_RUNNING ;
+
+    // We are going to enter right into the HRT
+    // HRT stack and argument passing
+    get_bp_loc(core->vm_info, &base,&limit);
+    // TODO: push description here
+    core->vm_regs.rsp = (v3_reg_t) base;  // so if we ret, we will blow up
+    core->vm_regs.rbp = (v3_reg_t) base; 
+    // TODO: RDI should really get pointer to description
+    core->vm_regs.rdi = (v3_reg_t) base;
+    // HRT entry point
+    get_hrt_loc(core->vm_info, &base,&limit);
+    core->rip = (uint64_t) core->vm_info->hvm_state.hrt_entry_addr ; 
+
+    // Setup CRs for long mode and our stub page table
+    // CR0: PG, PE
+    core->ctrl_regs.cr0 = 0x80000001;
+    core->shdw_pg_state.guest_cr0 = core->ctrl_regs.cr0;
+
+    // CR2: don't care (output from #PF)
+    // CE3: set to our PML4E, without setting PCD or PWT
+    get_pt_loc(core->vm_info, &base,&limit);
+    core->ctrl_regs.cr3 = PAGE_ADDR((addr_t)base);
+    core->shdw_pg_state.guest_cr3 = core->ctrl_regs.cr3;
+
+    // CR4: PGE, PAE, PSE (last byte: 1 0 1 1 0 0 0 0)
+    core->ctrl_regs.cr4 = 0xb0;
+    core->shdw_pg_state.guest_cr4 = core->ctrl_regs.cr4;
+    // CR8 as usual
+    // RFLAGS zeroed is fine: come in with interrupts off
+    // EFER needs SVME LMA LME (last 16 bits: 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0
+    core->ctrl_regs.efer = 0x1500;
+    core->shdw_pg_state.guest_efer.value = core->ctrl_regs.efer;
+
+
+    /* 
+       Notes on selectors:
+
+       selector is 13 bits of index, 1 bit table indicator 
+       (0=>GDT), 2 bit RPL
+       
+       index is scaled by 8, even in long mode, where some entries 
+       are 16 bytes long.... 
+          -> code, data descriptors have 8 byte format
+             because base, limit, etc, are ignored (no segmentation)
+          -> interrupt/trap gates have 16 byte format 
+             because offset needs to be 64 bits
+    */
+    
+    // Install our stub IDT
+    get_idt_loc(core->vm_info, &base,&limit);
+    core->segments.idtr.selector = 0;  // entry 0 (NULL) of the GDT
+    core->segments.idtr.base = (addr_t) base;
+    core->segments.idtr.limit = limit-1;
+    core->segments.idtr.type = 0xe;
+    core->segments.idtr.system = 1; 
+    core->segments.idtr.dpl = 0;
+    core->segments.idtr.present = 1;
+    core->segments.idtr.long_mode = 1;
+
+    // Install our stub GDT
+    get_gdt_loc(core->vm_info, &base,&limit);
+    core->segments.gdtr.selector = 0;
+    core->segments.gdtr.base = (addr_t) base;
+    core->segments.gdtr.limit = limit-1;
+    core->segments.gdtr.type = 0x6;
+    core->segments.gdtr.system = 1; 
+    core->segments.gdtr.dpl = 0;
+    core->segments.gdtr.present = 1;
+    core->segments.gdtr.long_mode = 1;
+    
+    // And our TSS
+    get_tss_loc(core->vm_info, &base,&limit);
+    core->segments.tr.selector = 0;
+    core->segments.tr.base = (addr_t) base;
+    core->segments.tr.limit = limit-1;
+    core->segments.tr.type = 0x6;
+    core->segments.tr.system = 1; 
+    core->segments.tr.dpl = 0;
+    core->segments.tr.present = 1;
+    core->segments.tr.long_mode = 1;
+    
+    base = 0x0;
+    limit = -1;
+
+    // And CS
+    core->segments.cs.selector = 0x8 ; // entry 1 of GDT (RPL=0)
+    core->segments.cs.base = (addr_t) base;
+    core->segments.cs.limit = limit;
+    core->segments.cs.type = 0xe;
+    core->segments.cs.system = 0; 
+    core->segments.cs.dpl = 0;
+    core->segments.cs.present = 1;
+    core->segments.cs.long_mode = 1;
+
+    // DS, SS, etc are identical
+    core->segments.ds.selector = 0x10; // entry 2 of GDT (RPL=0)
+    core->segments.ds.base = (addr_t) base;
+    core->segments.ds.limit = limit;
+    core->segments.ds.type = 0x6;
+    core->segments.ds.system = 0; 
+    core->segments.ds.dpl = 0;
+    core->segments.ds.present = 1;
+    core->segments.ds.long_mode = 1;
+    
+    memcpy(&core->segments.ss,&core->segments.ds,sizeof(core->segments.ds));
+    memcpy(&core->segments.es,&core->segments.ds,sizeof(core->segments.ds));
+    memcpy(&core->segments.fs,&core->segments.ds,sizeof(core->segments.ds));
+    memcpy(&core->segments.gs,&core->segments.ds,sizeof(core->segments.ds));
+    
+
+    if (core->vm_info->hvm_state.hrt_type==HRT_MBOOT64) { 
+       /*
+         Temporary hackery for multiboot2 "64"
+         We will push the MB structure onto the stack and update RSP
+         and RBX
+       */
+       uint8_t buf[256];
+       uint64_t size;
+       
+       if ((size=v3_build_multiboot_table(core,buf,256))==-1) { 
+           PrintError(core->vm_info,core,"hvm: Failed to write MB info\n");
+           return -1;
+       }
+       core->vm_regs.rsp -= size;
+
+       v3_write_gpa_memory(core,
+                           core->vm_regs.rsp,
+                           size,
+                           buf);
+
+       PrintDebug(core->vm_info,core, "hvm: wrote MB info at %p\n", (void*)core->vm_regs.rsp);
+
+       if (core->vcpu_id == core->vm_info->hvm_state.first_hrt_core) {
+           // We are the BSP for this HRT
+           // this is where rbx needs to point
+           core->vm_regs.rbx = core->vm_regs.rsp;
+           PrintDebug(core->vm_info,core, "hvm: \"BSP\" core\n");
+       } else {
+           // We are an AP for this HRT
+           // so we don't get the multiboot struct
+           core->vm_regs.rbx = 0;
+           PrintDebug(core->vm_info,core, "hvm: \"AP\" core\n");
+       }
+
+
+
+       // one more push, something that looks like a return address
+       size=0;
+       core->vm_regs.rsp -= 8;
+
+       v3_write_gpa_memory(core,
+                           core->vm_regs.rsp,
+                           8,
+                           (uint8_t*) &size);
        
+       // Now for our magic - this signals
+       // the kernel that a multiboot loader loaded it
+       // and that rbx points to its offered data
+       core->vm_regs.rax = MB2_INFO_MAGIC;
+    
+       /* 
+          Note that "real" MB starts in protected mode without paging
+          This hack starts in long mode... so these requirements go
+          out the window for a large part
+
+          Requirements:
+
+          OK EAX has magic 
+          OK EBX points to MB info
+          OK CS = base 0, offset big, code (LONG MODE)
+          OK DS,ES,FS,GS,SS => base 0, offset big, data (LONG MODE)
+          OK A20 gate on
+          XXX CR0 PE on PG off (nope)
+          XXX EFLAGS IF and VM off
+       */
+          
 
+
+    }
+
+
+    // reset paging here for shadow... 
+
+    if (core->shdw_pg_mode != NESTED_PAGING) { 
+       PrintError(core->vm_info, core, "hvm: shadow paging guest... this will end badly\n");
+       return -1;
+    }
+
+
+    return 0;
+}