[v2,0/4] target/i386: add support for FRED

Message

Li, Xin3 Oct. 2, 2023, 7:23 a.m. UTC

This patch set adds support for the Intel flexible return and event delivery
(FRED) architecture to allow Qemu to run KVM guests with FRED enabled.

The FRED architecture defines simple new transitions that change privilege
level (ring transitions). The FRED architecture was designed with the
following goals:
1) Improve overall performance and response time by replacing event delivery
   through the interrupt descriptor table (IDT event delivery) and event
   return by the IRET instruction with lower latency transitions.
2) Improve software robustness by ensuring that event delivery establishes
   the full supervisor context and that event return establishes the full
   user context.

Search for the latest FRED spec in most search engines with this search pattern:

  site:intel.com FRED (flexible return and event delivery) specification


---
Changelog
v2:
- Add VMX nested-exception support to scripts/kvm/vmxcap (Paolo Bonzini).
- Move FRED MSRs from basic x86_cpu part to .subsections part (Weijiang Yang).


Xin Li (4):
  target/i386: add support for FRED in CPUID enumeration
  target/i386: mark CR4.FRED not reserved
  target/i386: enumerate VMX nested-exception support
  target/i386: Add get/set/migrate support for FRED MSRs

 scripts/kvm/vmxcap    |  1 +
 target/i386/cpu.c     |  7 +++++-
 target/i386/cpu.h     | 43 +++++++++++++++++++++++++++++++++-
 target/i386/kvm/kvm.c | 54 +++++++++++++++++++++++++++++++++++++++++++
 target/i386/machine.c | 29 +++++++++++++++++++++++
 5 files changed, 132 insertions(+), 2 deletions(-)