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From: David Woodhouse <dwmw2@infradead.org>
To: kernel test robot <lkp@intel.com>, kvm <kvm@vger.kernel.org>
Cc: kbuild-all@lists.01.org, linux-kernel@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Joao Martins <joao.m.martins@oracle.com>,
	"jmattson@google.com" <jmattson@google.com>,
	"wanpengli@tencent.com" <wanpengli@tencent.com>,
	"seanjc@google.com" <seanjc@google.com>,
	"vkuznets@redhat.com" <vkuznets@redhat.com>,
	"mtosatti@redhat.com" <mtosatti@redhat.com>,
	"joro@8bytes.org" <joro@8bytes.org>,
	karahmed@amazon.com
Subject: [PATCH] KVM: Fix steal time asm constraints in 32-bit mode
Date: Sun, 14 Nov 2021 08:59:02 +0000	[thread overview]
Message-ID: <89bf72db1b859990355f9c40713a34e0d2d86c98.camel@infradead.org> (raw)
In-Reply-To: <202111141550.hY7mszt8-lkp@intel.com>

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From: David Woodhouse <dwmw@amazon.co.uk>

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".

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>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8f156905ae38..0a689bb62e9e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3307,7 +3307,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
 			     "xor %1, %1\n"
 			     "2:\n"
 			     _ASM_EXTABLE_UA(1b, 2b)
-			     : "+r" (st_preempted),
+			     : "+q" (st_preempted),
 			       "+&r" (err)
 			     : "m" (st->preempted));
 		if (err)
-- 
2.25.1


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  reply	other threads:[~2021-11-14  8:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-14  7:17 arch/x86/kvm/x86.c:3354:1: error: unsupported size for integer register kernel test robot
2021-11-14  8:59 ` David Woodhouse [this message]
2021-11-16  9:46   ` [PATCH] KVM: Fix steal time asm constraints in 32-bit mode Paolo Bonzini

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