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hvc_xen: make early_printk work with HVM guests

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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: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Stefano Stabellini 2016-02-25 12:10:39 +00:00
parent 5de738b3fb
commit a4d7b75be0
1 changed files with 16 additions and 11 deletions
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27
drivers/tty/hvc/hvc_xen.c
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@ -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, ...)