DM: Add funciton to update PM_WAK_STS

According to ACPI spec, when system back to working mode from
S3, WAK_STS bit (15) should be set.

Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Victor Sun <victor.sun@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

Author: fyin1

devicemodel/arch/x86/pm.c

@@ -175,6 +175,15 @@ pm1_status_handler(struct vmctx *ctx, int vcpu, int in, int port, int bytes,
 	return 0;
 }
 
+void
+pm_backto_wakeup(struct vmctx *ctx)
+{
+	/* According to ACPI 5.0 Table 4-16: bit 15, WAK_STS should be
+	 * set when system trasition to the working state
+	 */
+	pm1_status |= PM1_WAK_STS;
+}
+
 static int
 pm1_enable_handler(struct vmctx *ctx, int vcpu, int in, int port, int bytes,
 		   uint32_t *eax, void *arg)

devicemodel/core/main.c

@@ -622,6 +622,7 @@ vm_suspend_resume(struct vmctx *ctx)
 	vm_stop_watchdog(ctx);
 	wait_for_resume(ctx);
 
+	pm_backto_wakeup(ctx);
 	vm_reset_watchdog(ctx);
 	vm_reset(ctx);
 }

devicemodel/include/acpi.h

@@ -58,5 +58,6 @@ void	dsdt_indent(int levels);
 void	dsdt_unindent(int levels);
 void	sci_init(struct vmctx *ctx);
 void	pm_write_dsdt(struct vmctx *ctx, int ncpu);
+void	pm_backto_wakeup(struct vmctx *ctx);
 
 #endif /* _ACPI_H_ */