From 16e506efc08e5cab313588bd0e38803d4bbaad59 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Thu, 25 Feb 2016 12:10:37 +0000 Subject: hvc_xen: add earlycon support Introduce EARLYCON support in hvc_xen, useful for early debugging on arm and arm64, where xen early_printk is not available. It is different from xenboot_write_console on x86 in two ways: - it does not return if !xen_pv_domain(), not only because ARM guests are xen_hvm_domain(), but also because we want to capture all the early boot messages, before xen support is discovered - it does not try to print to the domU console at all, because xen support will only be discovered at a later point Signed-off-by: Stefano Stabellini Reviewed-by: Boris Ostrovsky --- drivers/tty/hvc/hvc_xen.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'drivers/tty/hvc') diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c index fa816b7193b6..68b8ec886bec 100644 --- a/drivers/tty/hvc/hvc_xen.c +++ b/drivers/tty/hvc/hvc_xen.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include @@ -664,3 +665,18 @@ void xen_raw_printk(const char *fmt, ...) xen_raw_console_write(buf); } + +static void xenboot_earlycon_write(struct console *console, + const char *string, + unsigned len) +{ + dom0_write_console(0, string, len); +} + +static int __init xenboot_earlycon_setup(struct earlycon_device *device, + const char *opt) +{ + device->con->write = xenboot_earlycon_write; + return 0; +} +EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup); -- cgit v1.2.3 From 5de738b3fbbd52a21850d5c1b6c1e5823db18b21 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Thu, 25 Feb 2016 12:10:38 +0000 Subject: hvc_xen: fix xenboot for DomUs The xenboot early console has been partially broken for DomU for a long time: the output would only go to the hypervisor via hypercall (HYPERVISOR_console_io), while it wouldn't actually go to the DomU console. The reason is that domU_write_console would return early as no xencons structs are configured for it. Add an appropriate xencons struct for xenboot from the xenboot setup callback. Signed-off-by: Stefano Stabellini Reviewed-by: Boris Ostrovsky --- drivers/tty/hvc/hvc_xen.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) (limited to 'drivers/tty/hvc') diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c index 68b8ec886bec..f34dec1d588a 100644 --- a/drivers/tty/hvc/hvc_xen.c +++ b/drivers/tty/hvc/hvc_xen.c @@ -246,6 +246,18 @@ err: return -ENODEV; } +static int xencons_info_pv_init(struct xencons_info *info, int vtermno) +{ + info->evtchn = xen_start_info->console.domU.evtchn; + /* GFN == MFN for PV guest */ + info->intf = gfn_to_virt(xen_start_info->console.domU.mfn); + info->vtermno = vtermno; + + list_add_tail(&info->list, &xenconsoles); + + return 0; +} + static int xen_pv_console_init(void) { struct xencons_info *info; @@ -265,13 +277,8 @@ static int xen_pv_console_init(void) /* already configured */ return 0; } - info->evtchn = xen_start_info->console.domU.evtchn; - /* GFN == MFN for PV guest */ - info->intf = gfn_to_virt(xen_start_info->console.domU.mfn); - info->vtermno = HVC_COOKIE; - spin_lock(&xencons_lock); - list_add_tail(&info->list, &xenconsoles); + xencons_info_pv_init(info, HVC_COOKIE); spin_unlock(&xencons_lock); return 0; @@ -599,6 +606,18 @@ static int xen_cons_init(void) console_initcall(xen_cons_init); #ifdef CONFIG_EARLY_PRINTK +static int __init xenboot_setup_console(struct console *console, char *string) +{ + static struct xencons_info xenboot; + + if (xen_initial_domain()) + return 0; + if (!xen_pv_domain()) + return -ENODEV; + + return xencons_info_pv_init(&xenboot, 0); +} + static void xenboot_write_console(struct console *console, const char *string, unsigned len) { @@ -629,6 +648,7 @@ static void xenboot_write_console(struct console *console, const char *string, struct console xenboot_console = { .name = "xenboot", .write = xenboot_write_console, + .setup = xenboot_setup_console, .flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME, .index = -1, }; -- cgit v1.2.3 From a4d7b75be034115d36b6a20db566eb8b11bacaf8 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Thu, 25 Feb 2016 12:10:39 +0000 Subject: 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: Stefano Stabellini Reviewed-by: Boris Ostrovsky --- drivers/tty/hvc/hvc_xen.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) (limited to 'drivers/tty/hvc') diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c index f34dec1d588a..71784950048f 100644 --- a/drivers/tty/hvc/hvc_xen.c +++ b/drivers/tty/hvc/hvc_xen.c @@ -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, ...) -- cgit v1.2.3