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KVM: Fix steal time asm constraints

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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: Rishabh Bhatnagar <risbhat@amazon.com>
Tested-by: Allen Pais <apais@linux.microsoft.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rishabh Bhatnagar 2023-05-10 18:15:41 +00:00 committed by Greg Kroah-Hartman
parent ebd3010d42
commit 8e39c2f407
1 changed files with 3 additions and 3 deletions
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6
arch/x86/kvm/x86.c
View File

@ -3064,9 +3064,9 @@ 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;