[tip: x86/urgent] x86/setup: Call early_reserve_memory() earlier

[tip-bot2 for Juergen Gross]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     1c1046581f1a3809e075669a3df0191869d96dd1
Gitweb:        https://git.kernel.org/tip/1c1046581f1a3809e075669a3df0191869d96dd1
Author:        Juergen Gross <jgross@xxxxxxxx>
AuthorDate:    Tue, 14 Sep 2021 11:41:08 +02:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 16 Sep 2021 12:38:05 +02:00

x86/setup: Call early_reserve_memory() earlier

Commit in Fixes introduced early_reserve_memory() to do all needed
initial memblock_reserve() calls in one function. Unfortunately, the call
of early_reserve_memory() is done too late for Xen dom0, as in some
cases a Xen hook called by e820__memory_setup() will need those memory
reservations to have happened already.

Move the call of early_reserve_memory() to the beginning of setup_arch()
in order to avoid such problems.

Fixes: a799c2bd29d1 ("x86/setup: Consolidate early memory reservations")
Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20210914094108.22482-1-jgross@xxxxxxxx
---
 arch/x86/kernel/setup.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index bff3a78..9095158 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -766,6 +766,20 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 
 void __init setup_arch(char **cmdline_p)
 {
+	/*
+	 * Do some memory reservations *before* memory is added to memblock, so
+	 * memblock allocations won't overwrite it.
+	 *
+	 * After this point, everything still needed from the boot loader or
+	 * firmware or kernel text should be early reserved or marked not RAM in
+	 * e820. All other memory is free game.
+	 *
+	 * This call needs to happen before e820__memory_setup() which calls
+	 * xen_memory_setup() on Xen dom0 which relies on the fact that those
+	 * early reservations have happened already.
+	 */
+	early_reserve_memory();
+
 #ifdef CONFIG_X86_32
 	memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
 
@@ -885,18 +899,6 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
-	/*
-	 * Do some memory reservations *before* memory is added to
-	 * memblock, so memblock allocations won't overwrite it.
-	 * Do it after early param, so we could get (unlikely) panic from
-	 * serial.
-	 *
-	 * After this point everything still needed from the boot loader or
-	 * firmware or kernel text should be early reserved or marked not
-	 * RAM in e820. All other memory is free game.
-	 */
-	early_reserve_memory();
-
 #ifdef CONFIG_MEMORY_HOTPLUG
 	/*
 	 * Memory used by the kernel cannot be hot-removed because Linux