Commit 31911d3c authored by Uros Bizjak's avatar Uros Bizjak Committed by Borislav Petkov (AMD)
Browse files

x86/paravirt: Use XOR r32,r32 to clear register in pv_vcpu_is_preempted() 



x86_64 zero extends 32bit operations, so for 64bit operands, XOR r32,r32 is
functionally equal to XOR r64,r64, but avoids a REX prefix byte when legacy
registers are used.

Signed-off-by: default avatarUros Bizjak <ubizjak@gmail.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
Acked-by: default avatarAlexey Makhalov <alexey.makhalov@broadcom.com>
Link: https://patch.msgid.link/20260114211948.74774-2-ubizjak@gmail.com
parent baea32b2

arch/x86/include/asm/paravirt-spinlock.h

+1 −1
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ static __always_inline void pv_queued_spin_unlock(struct qspinlock *lock) 
static __always_inline bool pv_vcpu_is_preempted(long cpu)

{

	return PVOP_ALT_CALLEE1(bool, pv_ops_lock, vcpu_is_preempted, cpu,

				"xor %%" _ASM_AX ", %%" _ASM_AX,

				"xor %%eax, %%eax",

				ALT_NOT(X86_FEATURE_VCPUPREEMPT));

}