Re: [Xen-devel] RE: kernel panic when enable x2apic

[Keir Fraser <keir@xxxxxxx>]

On 30/11/2010 08:50, "Weidong Han" <weidong.han@xxxxxxxxx> wrote:

> This results in Xen to allocate xsave
> area in vcpu_initialise, we observed it may allocate a used address for
> it, therefore cause the panic.

Actually you xmalloc a zero-sized area, and then immediately write past the
end of it, corrupting neigbouring data, including possibly xmalloc metadata.

> The obvious solution is to remove
> boot_cpu_data.x86_capability[4] = cpuid_ecx(1) in start_vmx. It indeed
> works with the change. I will send out the patch after more tests.

Yes, the write to x86_capability is totally unnecessary. There is a similar
pointless one in SVM code -- in fact they don't even manage to write to the
correct array element of x86_capability[]!

Removing both writes to x86_capability[] would be an appropriate fix for 4.0
branch as well.

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel