> -----Original Message----- > From: Jan Beulich [mailto:jbeul...@suse.com] > Sent: Tuesday, May 31, 2016 7:58 PM > To: Wu, Feng <feng...@intel.com> > Cc: andrew.coop...@citrix.com; dario.faggi...@citrix.com; > george.dun...@eu.citrix.com; Tian, Kevin <kevin.t...@intel.com>; xen- > de...@lists.xen.org; konrad.w...@oracle.com; k...@xen.org > Subject: RE: [PATCH v2 3/4] VMX: Assign the right value to 'NDST' field in a > concern case > > >>> On 31.05.16 at 12:27, <feng...@intel.com> wrote: > >> From: Jan Beulich [mailto:jbeul...@suse.com] > >> Sent: Friday, May 27, 2016 10:00 PM > >> >>> On 26.05.16 at 15:39, <feng...@intel.com> wrote: > >> > Normally, in vmx_cpu_block() 'NDST' filed should have the same > >> > value with 'dest' or 'MASK_INSR(dest, PI_xAPIC_NDST_MASK)' depending > >> > on whether x2apic is enabled. However, in the following scenario, > >> > 'NDST' has different value: > >> > > >> > 'vcpu_block' hook gets assigned in vmx_pi_hooks_assign(), but all > >> > other three PI hooks have not been assigned or not been excuted yet. > >> > And during this interval, we are running in vmx_vcpu_block(), then > >> > 'NDST' may have different value. > >> > >> How about simply assigning vcpu_block last? Or alternatively > >> holding pi_blocking_list_lock around all four assignments? Or > >> (maybe in addition to one of these) writing something sensible in > >> vmx_pi_hooks_assign() before doing the hook assignments? > > > > The problem is vmx_vcpu_block() can still get called first, since > > the other ones might not get called yet. > > That refers to the first two questions, yet the third (unanswered > one) was added by me because I anticipated that response. So > what's wrong with that last option?
Do you mean " Or (maybe in addition to one of these) writing something sensible in vmx_pi_hooks_assign() before doing the hook assignments?"? The problem is you cannot know whether vmx_vcpu_block() is called before or after the other hooks. And I am wondering why do you think the current solution is not good. Thanks, Feng > > Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
