hv: Prepare trampline.S trampoline code relocation

in real mode part, add extra pointers for page tables and long jump buffer
so it's possible for HV code to patch the relocation offset

in long mode part, use absolute addressing when referring HV symbols,
and use relative addressing for symbols within trampoline code

Signed-off-by: Zheng, Gen <gen.zheng@intel.com>
Signed-off-by: Jason Chen CJ <jason.cj.chen@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
Acked-by: Xu, Anthony <anthony.xu@intel.com>

hypervisor/arch/x86/trampline.S

@@ -31,6 +31,7 @@
    .align   4
    .code16
    .global      trampline_start16
+   .org 0
 trampline_start16:
 
     /* Disable local interrupts */
@@ -82,8 +83,9 @@ trampline_fixup_target:
 
     /* Set CR3 to PML4 table address */
 
-    movl    $CPU_Boot_Page_Tables_Start, %edi
+    movl    $CPU_Boot_Page_Tables_ptr, %ebx
-    mov     %edi, %cr3
+    mov     (%ebx), %eax
+    mov     %eax, %cr3
 
     /* Set LME bit in EFER */
 
@@ -104,7 +106,14 @@ trampline_fixup_target:
 
     /* Perform a long jump based to start executing in 64-bit mode */
 
-    data32 ljmp $HOST_GDT_RING0_CODE_SEL, $trampline_start64
+    movl    $trampline_start64_fixup, %ebx
+    ljmpl   *(%ebx)
+
+    .align 8
+    .global trampline_start64_fixup
+trampline_start64_fixup:
+    .long   trampline_start64
+    .word   HOST_GDT_RING0_CODE_SEL
 
     .code64
 trampline_start64:
@@ -119,7 +128,8 @@ trampline_start64:
     mov     %eax, %gs
 
     /* Obtain CPU spin-lock to serialize trampline for different APs */
-    spinlock_obtain(trampline_spinlock)
+    mov     $trampline_spinlock, %rdi
+    spinlock_obtain(%rdi)
 
     /* Initialize temporary stack pointer
        NOTE:  Using the PML4 memory (PDPT address is top of memory
@@ -130,7 +140,7 @@ trampline_start64:
               used for a VERY short period of time, so
               this reuse of PML4 memory should be acceptable. */
 
-    movq    $trampline_pdpt_addr, %rsp
+    lea     trampline_pdpt_addr(%rip), %rsp
 
     /* Push sp magic to top of stack for call trace */
     pushq   $SP_BOTTOM_MAGIC
@@ -139,8 +149,6 @@ trampline_start64:
     movq    main_entry(%rip), %rax
     jmp     %rax
 
-trampline_error:    /* should never come here */
-    jmp     trampline_error
 
 /* main entry */
     .align  8
@@ -158,17 +166,23 @@ trampline_gdt_end:
 
 /* GDT pointer */
     .align  2
+    .global trampline_gdt_ptr
 trampline_gdt_ptr:
     .short  (trampline_gdt_end - trampline_gdt) - 1
     .quad   trampline_gdt
 
 /* PML4, PDPT, and PD tables initialized to map first 4 GBytes of memory */
+    .align  4
+    .global CPU_Boot_Page_Tables_ptr
+CPU_Boot_Page_Tables_ptr:
+    .long CPU_Boot_Page_Tables_Start
 
     .align  CPU_PAGE_SIZE
     .global CPU_Boot_Page_Tables_Start
 CPU_Boot_Page_Tables_Start:
     .quad   trampline_pdpt_addr + (IA32E_COMM_P_BIT | IA32E_COMM_RW_BIT)
     .align  CPU_PAGE_SIZE
+    .global trampline_pdpt_addr
 trampline_pdpt_addr:
     address = 0
     .rept   4

hypervisor/bsp/ld/link_ram.ld.in

@@ -5,7 +5,7 @@ ENTRY(cpu_primary_start_32)
 MEMORY
 {
     /* Low 1MB of memory for secondary processor start-up */
-    lowram  :   ORIGIN = CONFIG_LOW_RAM_START, LENGTH = CONFIG_LOW_RAM_SIZE
+    lowram  :   ORIGIN = 0, LENGTH = CONFIG_LOW_RAM_SIZE
 
     /* 32 MBytes of RAM for HV */
     ram     :   ORIGIN = CONFIG_RAM_START, LENGTH = CONFIG_RAM_SIZE

hypervisor/include/arch/x86/cpu.h

@@ -158,10 +158,17 @@ int cpu_find_logical_id(uint32_t lapic_id);
 /**********************************/
 extern const uint8_t          _ld_trampline_load[];
 extern uint8_t                _ld_trampline_start[];
+extern uint8_t                _ld_trampline_end[];
 extern const uint64_t         _ld_trampline_size;
 extern uint8_t                _ld_bss_start[];
 extern uint8_t                _ld_bss_end[];
 
+extern uint8_t                CPU_Boot_Page_Tables_Start[];
+extern uint8_t                CPU_Boot_Page_Tables_ptr[];
+extern uint8_t                trampline_pdpt_addr[];
+extern uint8_t                trampline_gdt_ptr[];
+extern uint8_t                trampline_start64_fixup[];
+
 extern int ibrs_type;
 
 /*