hv: uart: enable early boot uart

Enable uart as early as possible to make things easier for debugging.
After this we could use printf to output information to the uart. As for
pr_xxx APIs, they start to work when init_logmsg is called.

Tracked-On: #2987
Signed-off-by: Li, Fei1 <fei1.li@intel.com>

hypervisor/arch/x86/cpu.c

@@ -26,6 +26,7 @@
 #include <cat.h>
 #include <vboot.h>
 #include <sgx.h>
+#include <uart16550.h>
 
 #define CPU_UP_TIMEOUT		100U /* millisecond */
 #define CPU_DOWN_TIMEOUT	100U /* millisecond */
@@ -106,6 +107,14 @@ void init_pcpu_pre(bool is_bsp)
 		/* Clear BSS */
 		(void)memset(&ld_bss_start, 0U, (size_t)(&ld_bss_end - &ld_bss_start));
 
+		(void)parse_hv_cmdline();
+		/*
+		 * WARNNING: here assume that vaddr2paddr is identical mapping.
+		 * Enable UART as early as possible.
+		 * Then we could use printf for debugging on early boot stage.
+		 */
+		uart16550_init(true);
+
 		/* Get CPU capabilities thru CPUID, including the physical address bit
 		 * limit which is required for initializing paging.
 		 */