Re: [PATCH] KVM: Avoid using vmx instruction directly

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Thursday 09 November 2006 12:08, Avi Kivity wrote:
> Index: linux-2.6/drivers/kvm/kvm_main.c
> ===================================================================
> --- 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
>         u64 phys_addr = __pa(vmcs);
>         u8 error;
>  
> -       asm volatile ("vmclear %1; setna %0"
> -                      : "=m"(error) : "m"(phys_addr) : "cc", "memory" );
> +       asm volatile (ASM_VMX_VMCLEAR_RAX "; setna %0"
> +                      : "=g"(error) : "a"(&phys_addr) : "cc", "memory" );
>         if (error)
>                 printk(KERN_ERR "kvm: vmclear fail: %p/%llx\n",
>                        vmcs, phys_addr);

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 <><

-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642