From 87304542f264d992f5922a704849130179224d5a Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@amazon.co.uk>
Date: Sun, 14 Nov 2021 08:59:02 +0000
Subject: [PATCH] KVM: Fix steal time asm constraints
Git-commit: 964b7aa0b040bdc6ec1c543ee620cda3f8b4c68a
Patch-mainline: v5.16-rc2
References: stable-5.14.21
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@intel.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-id: <89bf72db1b859990355f9c40713a34e0d2d86c98.camel@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
arch/x86/kvm/x86.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 285e86593143..599ed79581bf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3237,9 +3237,9 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
"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;
--
2.26.2