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Re: [PATCH] x86/HVM: don't mark evtchn upcall vector as pending when vLAPIC is disabled
On 18.11.22 11:31, Jan Beulich wrote:
Linux'es relatively new use of HVMOP_set_evtchn_upcall_vector has
exposed a problem with the marking of the respective vector as
pending: For quite some time Linux has been checking whether any stale
ISR or IRR bits would still be set while preparing the LAPIC for use.
This check is now triggering on the upcall vector, as the registration,
at least for APs, happens before the LAPIC is actually enabled.
In software-disabled state an LAPIC would not accept any interrupt
requests and hence no IRR bit would newly become set while in this
state. As a result it is also wrong for us to mark the upcall vector as
having a pending request when the vLAPIC is in this state.
To compensate for the "enabled" check added to the assertion logic, add
logic to (conditionally) mark the upcall vector as having a request
pending at the time the LAPIC is being software-enabled by the guest.
Fixes: 7b5b8ca7dffd ("x86/upcall: inject a spurious event after setting upcall
vector")
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Juergen
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