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Bug #13156

support APIC shorthand for self-IPI

Added by Patrick Mooney 8 days ago. Updated 8 days ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
kernel
Start date:
Due date:
% Done:

0%

Estimated time:
Difficulty:
Medium
Tags:
Gerrit CR:

Description

Per the architectural definition of the APIC, several shorthand notations are support for specifying IPI destination:

Destination Shorthand — A quick method of specifying all processors, all excluding self, or self as the destination.

While the all and all-but-self modes seem of dubious value for current kernel consumers, the self-ipi shorthand could be useful for VMM workloads which use them to incur guest exits after event injection. Indeed there may be some performance benefits:

The destination shorthand field of the ICR allows the delivery mode to be by-passed in favor of broadcasting the IPI to all the processors on the system bus and/or back to itself (see Section 10.6.1, “Interrupt Command Register (ICR)”). Three destination shorthands are supported: self, all excluding self, and all including self. The destination mode is ignored when a destination shorthand is used.

Using the tables provided in the SDM, such self-ipi shorthand must be constrained to only edge triggered interrupts in the fixed delivery mode.

History

#1

Updated by Electric Monk 8 days ago

  • Gerrit CR set to 929
#2

Updated by Ryan Zezeski 8 days ago

  • Gerrit CR deleted (929)

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