hv: add function to set AP entry

With reset_vcpu_regs as pre-condition, we only need to set
cs_selector and cs_base for AP.

We call set_ap_entry in two places:
 1. When emulation AP SIPI
 2. When sos BSP resume from S3. The BSP is resumed to real
    mode with entry set to wakeup_vec. We call set_ap_entry
    API here with entry twisted from wakeup_vec.

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/guest/vcpu.c

@@ -252,6 +252,17 @@ void reset_vcpu_regs(struct vcpu *vcpu)
 	set_vcpu_regs(vcpu, &realmode_init_regs);
 }
 
+void set_ap_entry(struct vcpu *vcpu, uint64_t entry)
+{
+	struct ext_context *ectx;
+
+	ectx = &(vcpu->arch_vcpu.contexts[vcpu->arch_vcpu.cur_context].ext_ctx);
+	ectx->cs.selector = (uint16_t)((entry >> 4UL) & 0xFFFFU);
+	ectx->cs.base = ectx->cs.selector << 4UL;
+
+	vcpu_set_rip(vcpu, 0UL);
+}
+
 /***********************************************************************
  *
  *  @pre vm != NULL && rtn_vcpu_handle != NULL

hypervisor/arch/x86/guest/vlapic.c

@@ -1207,11 +1207,11 @@ vlapic_icrlo_write_handler(struct acrn_vlapic *vlapic)
 				continue;
 			}
 
-			target_vcpu->arch_vcpu.cpu_mode = CPU_MODE_REAL;
-			target_vcpu->arch_vcpu.sipi_vector = vec;
 			pr_err("Start Secondary VCPU%hu for VM[%d]...",
 					target_vcpu->vcpu_id,
 					target_vcpu->vm->vm_id);
+			target_vcpu->arch_vcpu.cpu_mode = CPU_MODE_REAL;
+			set_ap_entry(target_vcpu, vec << 12U);
 			schedule_vcpu(target_vcpu);
 		} else if (mode == APIC_DELMODE_SMI) {
 			pr_info("vlapic: SMI IPI do not support\n");

hypervisor/arch/x86/guest/vm.c

@@ -374,10 +374,14 @@ void resume_vm_from_s3(struct vm *vm, uint32_t wakeup_vec)
 	vm->state = VM_STARTED;
 
 	reset_vcpu(bsp);
-	bsp->entry_addr = (void *)(uint64_t)wakeup_vec;
+
+	/* When SOS resume from S3, it will return to real mode
+	 * with entry set to wakeup_vec.
+	 */
 	bsp->arch_vcpu.cpu_mode = CPU_MODE_REAL;
-	init_vmcs(bsp);
+	set_ap_entry(bsp, wakeup_vec);
 
+	init_vmcs(bsp);
 	schedule_vcpu(bsp);
 }
 

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

@@ -287,6 +287,7 @@ uint64_t vcpu_get_pat_ext(struct vcpu *vcpu);
 void vcpu_set_pat_ext(struct vcpu *vcpu, uint64_t val);
 void set_vcpu_regs(struct vcpu *vcpu, struct acrn_vcpu_regs *vcpu_regs);
 void reset_vcpu_regs(struct vcpu *vcpu);
+void set_ap_entry(struct vcpu *vcpu, uint64_t entry);
 
 static inline bool is_long_mode(struct vcpu *vcpu)
 {