This is a note to let you know that I've just added the patch titled
x86/mm: fix poking_init() for Xen PV guests
to the 6.1-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-mm-fix-poking_init-for-xen-pv-guests.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 26ce6ec364f18d2915923bc05784084e54a5c4cc Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@xxxxxxxx>
Date: Mon, 9 Jan 2023 16:09:22 +0100
Subject: x86/mm: fix poking_init() for Xen PV guests
From: Juergen Gross <jgross@xxxxxxxx>
commit 26ce6ec364f18d2915923bc05784084e54a5c4cc upstream.
Commit 3f4c8211d982 ("x86/mm: Use mm_alloc() in poking_init()") broke
the kernel for running as Xen PV guest.
It seems as if the new address space is never activated before being
used, resulting in Xen rejecting to accept the new CR3 value (the PGD
isn't pinned).
Fix that by adding the now missing call of paravirt_arch_dup_mmap() to
poking_init(). That call was previously done by dup_mm()->dup_mmap() and
it is a NOP for all cases but for Xen PV, where it is just doing the
pinning of the PGD.
Fixes: 3f4c8211d982 ("x86/mm: Use mm_alloc() in poking_init()")
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20230109150922.10578-1-jgross@xxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/init.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -27,6 +27,7 @@
#include <asm/pti.h>
#include <asm/text-patching.h>
#include <asm/memtype.h>
+#include <asm/paravirt.h>
/*
* We need to define the tracepoints somewhere, and tlb.c
@@ -829,6 +830,9 @@ void __init poking_init(void)
poking_mm = copy_init_mm();
BUG_ON(!poking_mm);
+ /* Xen PV guests need the PGD to be pinned. */
+ paravirt_arch_dup_mmap(NULL, poking_mm);
+
/*
* Randomize the poking address, but make sure that the following page
* will be mapped at the same PMD. We need 2 pages, so find space for 3,
Patches currently in stable-queue which might be from jgross@xxxxxxxx are
queue-6.1/x86-mm-fix-poking_init-for-xen-pv-guests.patch
queue-6.1/x86-xen-fix-secondary-processors-fpu-initialization.patch
queue-6.1/xen-netback-fix-buffer-overrun-triggered-by-unusual-packet.patch
