x86/PVH: obtain VGA console info in Dom0

A new platform-op was added to Xen to allow obtaining the same VGA
console information PV Dom0 is handed. Invoke the new function and have
the output data processed by xen_init_vga().
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

Link: https://lore.kernel.org/r/8f315e92-7bda-c124-71cc-478ab9c5e610@suse.comSigned-off-by: Juergen Gross <jgross@suse.com>

arch/x86/xen/Makefile

@@ -45,6 +45,6 @@ obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
 
 obj-$(CONFIG_XEN_DEBUG_FS)	+= debugfs.o
 
-obj-$(CONFIG_XEN_PV_DOM0)	+= vga.o
+obj-$(CONFIG_XEN_DOM0)		+= vga.o
 
 obj-$(CONFIG_XEN_EFI)		+= efi.o

arch/x86/xen/enlighten_pv.c

@@ -1389,7 +1389,8 @@ asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
 
 		x86_platform.set_legacy_features =
 				xen_dom0_set_legacy_features;
-		xen_init_vga(info, xen_start_info->console.dom0.info_size);
+		xen_init_vga(info, xen_start_info->console.dom0.info_size,
+			     &boot_params.screen_info);
 		xen_start_info->console.domU.mfn = 0;
 		xen_start_info->console.domU.evtchn = 0;
 

arch/x86/xen/enlighten_pvh.c

@@ -43,6 +43,19 @@ void __init xen_pvh_init(struct boot_params *boot_params)
 	x86_init.oem.banner = xen_banner;
 
 	xen_efi_init(boot_params);
+
+	if (xen_initial_domain()) {
+		struct xen_platform_op op = {
+			.cmd = XENPF_get_dom0_console,
+		};
+		long ret = HYPERVISOR_platform_op(&op);
+
+		if (ret > 0)
+			xen_init_vga(&op.u.dom0_console,
+				     min(ret * sizeof(char),
+					 sizeof(op.u.dom0_console)),
+				     &boot_params->screen_info);
+	}
 }
 
 void __init mem_map_via_hcall(struct boot_params *boot_params_p)

arch/x86/xen/vga.c

@@ -9,10 +9,9 @@
 
 #include "xen-ops.h"
 
-void __init xen_init_vga(const struct dom0_vga_console_info *info, size_t size)
+void __init xen_init_vga(const struct dom0_vga_console_info *info, size_t size,
+			 struct screen_info *screen_info)
 {
-	struct screen_info *screen_info = &boot_params.screen_info;
-
 	/* This is drawn from a dump from vgacon:startup in
 	 * standard Linux. */
 	screen_info->orig_video_mode = 3;

arch/x86/xen/xen-ops.h

@@ -108,11 +108,12 @@ static inline void xen_uninit_lock_cpu(int cpu)
 
 struct dom0_vga_console_info;
 
-#ifdef CONFIG_XEN_PV_DOM0
-void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size);
+#ifdef CONFIG_XEN_DOM0
+void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size,
+			 struct screen_info *);
 #else
 static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
-				       size_t size)
+				       size_t size, struct screen_info *si)
 {
 }
 #endif

include/xen/interface/platform.h

@@ -483,6 +483,8 @@ struct xenpf_symdata {
 };
 DEFINE_GUEST_HANDLE_STRUCT(xenpf_symdata);
 
+#define XENPF_get_dom0_console 64
+
 struct xen_platform_op {
 	uint32_t cmd;
 	uint32_t interface_version; /* XENPF_INTERFACE_VERSION */
@@ -506,6 +508,7 @@ struct xen_platform_op {
 		struct xenpf_mem_hotadd        mem_add;
 		struct xenpf_core_parking      core_parking;
 		struct xenpf_symdata           symdata;
+		struct dom0_vga_console_info   dom0_console;
 		uint8_t                        pad[128];
 	} u;
 };