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Commit a4d7b75b authored by Stefano Stabellini's avatar Stefano Stabellini
Browse files

hvc_xen: make early_printk work with HVM guests 



Refactor the existing code in xen_raw_console_write to get the generic
early_printk console work with HVM guests.

Take the opportunity to replace the outb loop with a single outsb call
to reduce the number of vmexit.

Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent 5de738b3

drivers/tty/hvc/hvc_xen.c

+16 −11
Original line number Diff line number Diff line
@@ -605,6 +605,16 @@ static int xen_cons_init(void) 
}

console_initcall(xen_cons_init);



#ifdef CONFIG_X86

static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len)

{

	if (xen_cpuid_base())

		outsb(0xe9, str, len);

}

#else

static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }

#endif



#ifdef CONFIG_EARLY_PRINTK

static int __init xenboot_setup_console(struct console *console, char *string)

{
@@ -624,8 +634,10 @@ static void xenboot_write_console(struct console *console, const char *string, 
	unsigned int linelen, off = 0;

	const char *pos;



	if (!xen_pv_domain())

	if (!xen_pv_domain()) {

		xen_hvm_early_write(0, string, len);

		return;

	}



	dom0_write_console(0, string, len);
@@ -661,17 +673,10 @@ void xen_raw_console_write(const char *str) 


	if (xen_domain()) {

		rc = dom0_write_console(0, str, len);

#ifdef CONFIG_X86

		if (rc == -ENOSYS && xen_hvm_domain())

			goto outb_print;



	} else if (xen_cpuid_base()) {

		int i;

outb_print:

		for (i = 0; i < len; i++)

			outb(str[i], 0xe9);

#endif

		if (rc != -ENOSYS || !xen_hvm_domain())

			return;

	}

	xen_hvm_early_write(0, str, len);

}



void xen_raw_printk(const char *fmt, ...)