KVM: SVM: Set target pCPU during IRTE update if target vCPU is running

Update the target pCPU for IOMMU doorbells when updating IRTE routing if
KVM is actively running the associated vCPU.  KVM currently only updates
the pCPU when loading the vCPU (via avic_vcpu_load()), and so doorbell
events will be delayed until the vCPU goes through a put+load cycle (which
might very well "never" happen for the lifetime of the VM).

To avoid inserting a stale pCPU, e.g. due to racing between updating IRTE
routing and vCPU load/put, get the pCPU information from the vCPU's
Physical APIC ID table entry (a.k.a. avic_physical_id_cache in KVM) and
update the IRTE while holding ir_list_lock.  Add comments with --verbose
enabled to explain exactly what is and isn't protected by ir_list_lock.

Fixes: 411b44ba80ab ("svm: Implements update_pi_irte hook to setup posted interrupt")
Reported-by: dengqiao.joey <[email protected]>
Cc: [email protected]
Cc: Alejandro Jimenez <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Maxim Levitsky <[email protected]>
Cc: Suravee Suthikulpanit <[email protected]>
Tested-by: Alejandro Jimenez <[email protected]>
Reviewed-by: Joao Martins <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>

0 files changed, 0 insertions, 0 deletions