Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.15 04/20] KVM: Fix steal time asm constraints | Date | Fri, 19 Nov 2021 18:39:22 +0100 |
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From: David Woodhouse <dwmw@amazon.co.uk>
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> --- 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;
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