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05 April 2024, 19:05:47 UTC
Revision c112b5f50232a257056903040c66d97efb536889 authored by Luwei Kang on 14 February 2019, 02:48:07 UTC, committed by Paolo Bonzini on 14 February 2019, 15:20:31 UTC 
KVM: x86: Recompute PID.ON when clearing PID.SN
 
Some Posted-Interrupts from passthrough devices may be lost or
overwritten when the vCPU is in runnable state.

The SN (Suppress Notification) of PID (Posted Interrupt Descriptor) will
be set when the vCPU is preempted (vCPU in KVM_MP_STATE_RUNNABLE state but
not running on physical CPU). If a posted interrupt comes at this time,
the irq remapping facility will set the bit of PIR (Posted Interrupt
Requests) but not ON (Outstanding Notification).  Then, the interrupt
will not be seen by KVM, which always expects PID.ON=1 if PID.PIR=1
as documented in the Intel processor SDM but not in the VT-d specification.
To fix this, restore the invariant after PID.SN is cleared.

Signed-off-by: Luwei Kang <luwei.kang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent 08e1675
History
Tip revision: c112b5f50232a257056903040c66d97efb536889 authored by Luwei Kang on 14 February 2019, 02:48:07 UTC
KVM: x86: Recompute PID.ON when clearing PID.SN
Tip revision: c112b5f
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