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Re: [Xen-devel] [PATCH V3] x86/vm_event: block interrupt injection for sync vm_events



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).

Could you please take a look?


Thanks,
Razvan

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