[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V3] x86/vm_event: block interrupt injection for sync vm_events
On 14/01/2019 11:56, Razvan Cojocaru wrote: > On 1/14/19 11:53 AM, Jan Beulich wrote: >>>>> On 14.01.19 at 10:34, <rcojocaru@xxxxxxxxxxxxxxx> wrote: >>> On 1/12/19 12:04 AM, Boris Ostrovsky wrote: >>>> On 12/14/18 6:49 AM, Razvan Cojocaru wrote: >>>>> Block interrupts (in vmx_intr_assist()) for the duration of >>>>> processing a sync vm_event (similarly to the strategy >>>>> currently used for single-stepping). Otherwise, attempting >>>>> to emulate an instruction when requested by a vm_event >>>>> reply may legitimately need to call e.g. >>>>> hvm_inject_page_fault(), which then overwrites the active >>>>> interrupt in the VMCS. >>>>> >>>>> The sync vm_event handling path on x86/VMX is (roughly): >>>>> monitor_traps() -> process vm_event -> vmx_intr_assist() >>>>> (possibly writing VM_ENTRY_INTR_INFO) -> >>>>> hvm_vm_event_do_resume() -> hvm_emulate_one_vm_event() >>>>> (possibly overwriting the VM_ENTRY_INTR_INFO value). >>>>> >>>>> This patch may also be helpful for the future removal >>>>> of may_defer in hvm_set_cr{0,3,4} and hvm_set_msr(). >>>>> >>>>> Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx> >>>> >>>> >>>> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> >>> >>> Thanks! So now we have three reviewed-bys, if I'm not mistaken all we >>> need is Tamas' (for the vm_event part) and Julien / Stefano's (for ARM) >>> acks (or otherwise). >> >> And you'd need to talk Jürgen into allowing this in, now that we're >> past the freeze point. > > (Adding Jürgen to the conversation.) > > Right, that would be ideal if possible - the code has absolutely no > impact on anything unless vm_event is active on the domain, which is > never the case for the use-cases considered for a Xen release. > > So the case I'm making for the patch to go in 4.12 is that: > > 1. It's perfectly harmless (it affects nothing, except for introspection). > > 2. It's trivial and thus very easy to see that it's correct. > > 3. It fixes a major headache for us, and thus it is a great improvement > from an introspection standpoint (fixes OS crashes / hangs which we'd > otherwise need to work around in rather painful ways). > > 4. V3 of the patch has been sent out on Dec 14th - it's just that > reviewers have had other priorities and it did not gather all acks in time. > > However, if it's not possible or desirable to allow this in the next > best thing is to at least have all the acks necessary for it to go in > first thing once the freeze is over. > > From Julien's reply I understand that the last ack necessary is Tamas'. With that ack just arrived: Release-acked-by: Juergen Gross <jgross@xxxxxxxx> Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |