From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
Subject: Re: [PATCH] KVM: Avoid using vmx instruction directly
Date: Thu, 9 Nov 2006 14:29:41 +0100
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On Thursday 09 November 2006 12:08, Avi Kivity wrote:
> Index: linux-2.6/drivers/kvm/kvm_main.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- linux-2.6.orig/drivers/kvm/kvm_main.c
> +++ linux-2.6/drivers/kvm/kvm_main.c
> @@ -369,8 +369,8 @@ static void vmcs_clear(struct vmcs *vmcs
> =A0=A0=A0=A0=A0=A0=A0=A0u64 phys_addr =3D __pa(vmcs);
> =A0=A0=A0=A0=A0=A0=A0=A0u8 error;
> =A0
> -=A0=A0=A0=A0=A0=A0=A0asm volatile ("vmclear %1; setna %0"
> -=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0 =A0 =A0 : "=3Dm"(error=
) : "m"(phys_addr) : "cc", "memory" );
> +=A0=A0=A0=A0=A0=A0=A0asm volatile (ASM_VMX_VMCLEAR_RAX "; setna %0"
> +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0 =A0 =A0 : "=3Dg"(error=
) : "a"(&phys_addr) : "cc", "memory" );
> =A0=A0=A0=A0=A0=A0=A0=A0if (error)
> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0printk(KERN_ERR "kvm: vmc=
lear fail: %p/%llx\n",
> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0 =A0 =A0 vmcs, phys_a=
ddr);

I'm not an expert on inline assembly, but don't you need an extra
'"m" (phys_addr)' to make sure that gcc actually puts the variable
on the stack instead of passing a NULL pointer as '"a"(&phys_addr)'?

	Arnd <><

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