hv: create gdt for guest to start from protected mode

In current implementation, on sbl platform, vm0 bsp
starts from 64bit mode. And hv need to prepare init
page table for it.

In this patch series, on sbl platform, vm0 bsp starts
from non-paging protected mode.
This patch prepares an init gdt for vm0 bsp on sbl
platform.

Signed-off-by: Binbin Wu <binbin.wu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Reviewed-by: Eddie Dong <eddie.dong@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Xu, Anthony <anthony.xu@intel.com>

Author: binbinwu1

hypervisor/arch/x86/guest/guest.c

@@ -680,3 +680,36 @@ uint64_t create_guest_initial_paging(struct vm *vm)
 
 	return GUEST_INIT_PAGE_TABLE_START;
 }
+
+/*******************************************************************
+ *         GUEST initial GDT table
+ *
+ * If guest starts with protected mode, HV needs to prepare Guest GDT.
+ ******************************************************************/
+
+#define GUEST_INIT_GDT_SKIP_SIZE	0x8000UL
+#define GUEST_INIT_GDT_START	(CONFIG_LOW_RAM_START +	\
+					GUEST_INIT_GDT_SKIP_SIZE)
+
+/* The GDT defined below compatible with linux kernel */
+#define GUEST_INIT_GDT_DESC_0	(0x0)
+#define GUEST_INIT_GDT_DESC_1	(0x0)
+#define GUEST_INIT_GDT_DESC_2	(0x00CF9B000000FFFFULL) /* Linear Code */
+#define GUEST_INIT_GDT_DESC_3	(0x00CF93000000FFFFULL) /* Linear Data */
+
+static const uint64_t guest_init_gdt[] = {
+	GUEST_INIT_GDT_DESC_0,
+	GUEST_INIT_GDT_DESC_1,
+	GUEST_INIT_GDT_DESC_2,
+	GUEST_INIT_GDT_DESC_3,
+};
+
+uint32_t create_guest_init_gdt(struct vm *vm, uint32_t *limit)
+{
+	void *gtd_addr = GPA2HVA(vm, GUEST_INIT_GDT_START);
+
+	*limit = sizeof(guest_init_gdt) - 1;
+	memcpy_s(gtd_addr, 64, guest_init_gdt, sizeof(guest_init_gdt));
+
+	return GUEST_INIT_GDT_START;
+};

hypervisor/include/arch/x86/guest/guest.h

@@ -123,6 +123,8 @@ extern vm_sw_loader_t vm_sw_loader;
 
 int copy_from_vm(struct vm *vm, void *h_ptr, uint64_t gpa, uint32_t size);
 int copy_to_vm(struct vm *vm, void *h_ptr, uint64_t gpa, uint32_t size);
+
+uint32_t create_guest_init_gdt(struct vm *vm, uint32_t *limit);
 #endif	/* !ASSEMBLER */
 
 #endif /* GUEST_H*/