This is a note to let you know that I've just added the patch titled
x86/xen: Use clear_bss() for Xen PV guests
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-xen-use-clear_bss-for-xen-pv-guests.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 96e8fc5818686d4a1591bb6907e7fdb64ef29884 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@xxxxxxxx>
Date: Thu, 30 Jun 2022 09:14:39 +0200
Subject: x86/xen: Use clear_bss() for Xen PV guests
From: Juergen Gross <jgross@xxxxxxxx>
commit 96e8fc5818686d4a1591bb6907e7fdb64ef29884 upstream.
Instead of clearing the bss area in assembly code, use the clear_bss()
function.
This requires to pass the start_info address as parameter to
xen_start_kernel() in order to avoid the xen_start_info being zeroed
again.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220630071441.28576-2-jgross@xxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/setup.h | 3 +++
arch/x86/kernel/head64.c | 2 +-
arch/x86/xen/enlighten_pv.c | 8 ++++++--
arch/x86/xen/xen-head.S | 10 +---------
4 files changed, 11 insertions(+), 12 deletions(-)
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -132,6 +132,9 @@ void *extend_brk(size_t size, size_t ali
}
extern void probe_roms(void);
+
+void clear_bss(void);
+
#ifdef __i386__
asmlinkage void __init i386_start_kernel(void);
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -421,7 +421,7 @@ void __init do_early_exception(struct pt
/* Don't add a printk in there. printk relies on the PDA which is not initialized
yet. */
-static void __init clear_bss(void)
+void __init clear_bss(void)
{
memset(__bss_start, 0,
(unsigned long) __bss_stop - (unsigned long) __bss_start);
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1183,15 +1183,19 @@ static void __init xen_domu_set_legacy_f
extern void early_xen_iret_patch(void);
/* First C function to be called on Xen boot */
-asmlinkage __visible void __init xen_start_kernel(void)
+asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
{
struct physdev_set_iopl set_iopl;
unsigned long initrd_start = 0;
int rc;
- if (!xen_start_info)
+ if (!si)
return;
+ clear_bss();
+
+ xen_start_info = si;
+
__text_gen_insn(&early_xen_iret_patch,
JMP32_INSN_OPCODE, &early_xen_iret_patch, &xen_iret,
JMP32_INSN_SIZE);
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -48,15 +48,6 @@ SYM_CODE_START(startup_xen)
ANNOTATE_NOENDBR
cld
- /* Clear .bss */
- xor %eax,%eax
- mov $__bss_start, %rdi
- mov $__bss_stop, %rcx
- sub %rdi, %rcx
- shr $3, %rcx
- rep stosq
-
- mov %rsi, xen_start_info
mov initial_stack(%rip), %rsp
/* Set up %gs.
@@ -71,6 +62,7 @@ SYM_CODE_START(startup_xen)
cdq
wrmsr
+ mov %rsi, %rdi
call xen_start_kernel
SYM_CODE_END(startup_xen)
__FINIT
Patches currently in stable-queue which might be from jgross@xxxxxxxx are
queue-5.18/x86-xen-use-clear_bss-for-xen-pv-guests.patch
