HV: save the cs limit field for SOS

Save the native cs limit and reuse it for SOS cs limit. To remove
the hardcode of cs limit for guest in hypervisor.

Tracked-On: #1231
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Acked-by: Eddie Dong <Eddie.dong@intel.com>

Author: fyin1

hypervisor/arch/x86/cpu_save_boot_ctx.S

@@ -32,6 +32,13 @@ cpu_primary_save_32:
     /* Clear Limit field, bit 8-11 */
     andl    $0x0000f0ff, %ecx
     mov     %ecx, BOOT_CTX_CS_AR_OFFSET(%eax)
+
+    /* Save CS limit field */
+    mov     %cs, %cx
+    xor     %edx, %edx
+    lsl     %ecx, %edx
+    mov     %edx, BOOT_CTX_CS_LIMIT_OFFSET(%eax)
+
     mov     %es,  BOOT_CTX_ES_SEL_OFFSET(%eax)
     mov     %ss,  BOOT_CTX_SS_SEL_OFFSET(%eax)
     mov     %ds,  BOOT_CTX_DS_SEL_OFFSET(%eax)
@@ -62,6 +69,13 @@ cpu_primary_save_64:
     /* Clear Limit field, bit 8-11 */
     andl    $0x0000f0ff, %ecx
     mov     %ecx, BOOT_CTX_CS_AR_OFFSET(%r8)
+
+    /* Save CS limit field */
+    mov     %cs, %cx
+    xor     %edx, %edx
+    lsl     %ecx, %edx
+    mov     %edx, BOOT_CTX_CS_LIMIT_OFFSET(%r8)
+
     mov     %es,  BOOT_CTX_ES_SEL_OFFSET(%r8)
     mov     %ss,  BOOT_CTX_SS_SEL_OFFSET(%r8)
     mov     %ds,  BOOT_CTX_DS_SEL_OFFSET(%r8)

hypervisor/include/arch/x86/guest/vm0_boot.h

@@ -22,6 +22,7 @@
 #define BOOT_CTX_FS_SEL_OFFSET      276
 #define BOOT_CTX_GS_SEL_OFFSET      278
 #define BOOT_CTX_CS_AR_OFFSET       248
+#define BOOT_CTX_CS_LIMIT_OFFSET    252
 #define BOOT_CTX_EFER_LOW_OFFSET    200
 #define BOOT_CTX_EFER_HIGH_OFFSET   204
 #define SIZE_OF_BOOT_CTX            296
@@ -40,6 +41,7 @@
 #define BOOT_CTX_FS_SEL_OFFSET      276U
 #define BOOT_CTX_GS_SEL_OFFSET      278U
 #define BOOT_CTX_CS_AR_OFFSET       248U
+#define BOOT_CTX_CS_LIMIT_OFFSET    252U
 #define BOOT_CTX_EFER_LOW_OFFSET    200U
 #define BOOT_CTX_EFER_HIGH_OFFSET   204U
 #define SIZE_OF_BOOT_CTX            296U

hypervisor/include/public/acrn_common.h

@@ -295,7 +295,8 @@ struct acrn_vcpu_regs {
 	uint64_t        reserved_64[4];
 
 	uint32_t        cs_ar;
-	uint32_t        reserved_32[4];
+	uint32_t        cs_limit;
+	uint32_t        reserved_32[3];
 
 	/* don't change the order of following sel */
 	uint16_t        cs_sel;