From 4d1ab432acc9391a5ae13c629dbb5882c29fd1b0 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Thu, 30 Sep 2021 14:19:16 +0200
Subject: [PATCH] xen/x86: generalize preferred console model from PV to PVH
 Dom0

Without announcing hvc0 as preferred it won't get used as long as tty0
gets registered earlier. This is particularly problematic with there not
being any screen output for PVH Dom0 when the screen is in graphics
mode, as the necessary information doesn't get conveyed yet from the
hypervisor.

Follow PV's model, but be conservative and do this for Dom0 only for
now.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/582328b6-c86c-37f3-d802-5539b7a86736@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/xen/enlighten.c     | 12 ++++++++++++
 arch/x86/xen/enlighten_pv.c  |  8 +-------
 arch/x86/xen/enlighten_pvh.c |  3 +++
 arch/x86/xen/xen-ops.h       |  2 ++
 4 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 5014660..c5b1fd606 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -3,6 +3,7 @@
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
 #include <linux/memblock.h>
 #endif
+#include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/kexec.h>
 #include <linux/slab.h>
@@ -18,6 +19,7 @@
 #include <asm/xen/hypervisor.h>
 #include <asm/cpu.h>
 #include <asm/e820/api.h> 
+#include <asm/setup.h>
 
 #include "xen-ops.h"
 #include "smp.h"
@@ -274,6 +276,16 @@ bool xen_running_on_version_or_later(unsigned int major, unsigned int minor)
 	return false;
 }
 
+void __init xen_add_preferred_consoles(void)
+{
+	add_preferred_console("xenboot", 0, NULL);
+	if (!boot_params.screen_info.orig_video_isVGA)
+		add_preferred_console("tty", 0, NULL);
+	add_preferred_console("hvc", 0, NULL);
+	if (boot_params.screen_info.orig_video_isVGA)
+		add_preferred_console("tty", 0, NULL);
+}
+
 void xen_reboot(int reason)
 {
 	struct sched_shutdown r = { .reason = reason };
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index b1c0e06..fb3095b 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -28,7 +28,6 @@
 #include <linux/mm.h>
 #include <linux/page-flags.h>
 #include <linux/highmem.h>
-#include <linux/console.h>
 #include <linux/pci.h>
 #include <linux/gfp.h>
 #include <linux/edd.h>
@@ -1392,12 +1391,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 #endif
 	}
 
-	add_preferred_console("xenboot", 0, NULL);
-	if (!boot_params.screen_info.orig_video_isVGA)
-		add_preferred_console("tty", 0, NULL);
-	add_preferred_console("hvc", 0, NULL);
-	if (boot_params.screen_info.orig_video_isVGA)
-		add_preferred_console("tty", 0, NULL);
+	xen_add_preferred_consoles();
 
 #ifdef CONFIG_PCI
 	/* PCI BIOS service won't work from a PV guest. */
diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
index 0d5e34b..9029c5ab 100644
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -36,6 +36,9 @@ void __init xen_pvh_init(struct boot_params *boot_params)
 	pfn = __pa(hypercall_page);
 	wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
 
+	if (xen_initial_domain())
+		x86_init.oem.arch_setup = xen_add_preferred_consoles;
+
 	xen_efi_init(boot_params);
 }
 
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 6d9b2b3..524d124 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -118,6 +118,8 @@ static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
 }
 #endif
 
+void xen_add_preferred_consoles(void);
+
 void __init xen_init_apic(void);
 
 #ifdef CONFIG_XEN_EFI
-- 
2.7.4