[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH for-4.12] x86/altp2m: fix HVMOP_altp2m_set_domain_state race
On 2/8/19 12:51 PM, Jan Beulich wrote: Well, yes, that would have been my second attempt: set the "altp2m enabled" bool after the init, and before the uninit and no longer domain_pause() explicitly; however I thought that was a brittle solution, relying on comments / programmer attention to the code sequence rather than taking a proper lock.On 08.02.19 at 10:56, <rcojocaru@xxxxxxxxxxxxxxx> wrote:HVMOP_altp2m_set_domain_state does not domain_pause(), presumably on purpose (as it was originally supposed to cater to a in-guest agent, and a domain pausing itself is not a good idea). This can lead to domain crashes in the vmx_vmexit_handler() code that checks if the guest has the ability to switch EPTP without an exit. That code can __vmread() the host p2m's EPT_POINTER (before HVMOP_altp2m_set_domain_state "for_each_vcpu()" has a chance to run altp2m_vcpu_initialise(), but after d->arch.altp2m_active is set). While the in-guest scenario continues to pose problems, this patch fixes the "external" case.IOW you're papering over the problem rather than fixing it. Why does altp2m_active get set to true before actually having set up everything? Shouldn't it get cleared early, but set late? I'll test that scenario then and return with the results / possibly another patch. Thanks, Razvan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |