This is a note to let you know that I've just added the patch titled
KVM: Fix steal time asm constraints
to the 5.15-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:
kvm-fix-steal-time-asm-constraints.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 964b7aa0b040bdc6ec1c543ee620cda3f8b4c68a Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Date: Sun, 14 Nov 2021 08:59:02 +0000
Subject: KVM: Fix steal time asm constraints
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
commit 964b7aa0b040bdc6ec1c543ee620cda3f8b4c68a upstream.
In 64-bit mode, x86 instruction encoding allows us to use the low 8 bits
of any GPR as an 8-bit operand. In 32-bit mode, however, we can only use
the [abcd] registers. For which, GCC has the "q" constraint instead of
the less restrictive "r".
Also fix st->preempted, which is an input/output operand rather than an
input.
Fixes: 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempted status")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Message-Id: <89bf72db1b859990355f9c40713a34e0d2d86c98.camel@xxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3242,9 +3242,9 @@ static void record_steal_time(struct kvm
"xor %1, %1\n"
"2:\n"
_ASM_EXTABLE_UA(1b, 2b)
- : "+r" (st_preempted),
- "+&r" (err)
- : "m" (st->preempted));
+ : "+q" (st_preempted),
+ "+&r" (err),
+ "+m" (st->preempted));
if (err)
goto out;
Patches currently in stable-queue which might be from dwmw@xxxxxxxxxxxx are
queue-5.15/kvm-fix-steal-time-asm-constraints.patch
