On 8/1/19 4:59 PM, Thomas Gleixner wrote: > On Thu, 1 Aug 2019, Peter Zijlstra wrote: >> On Thu, Aug 01, 2019 at 11:34:23PM +0200, Thomas Gleixner wrote: >>> Avoid the whole NMI mess, make the PMC interrupt a proper vector in the >>> highest prio bucket and instead of using CLI/STI use CR8. That would have >>> the additional advantage that we could prevent perf "NMI" then occsionally >>> :) >> >> Exactly, and not only the PMC, we can basically start giving out actual >> vectors on register_nmi_handler() and do away with all that shared line >> crap. >> >> And then the actual NMI line will be mostly empty again, and it can read >> its stupid slow reason port again. >> >> One complication though; IRET et al only do EFLAGS, not CR8, so that's >> going to be massive fun :-(
Talking to the hardware folks, they say setting CR8 is a serializing instruction and has to communicate out to the APIC, so it's better to use CLI/STI. Thanks, Tom >> >> Did I say I hates the x86 interrupt scheme? > > You're not alone. > > That stuff definitely violates article 3 of the Convention for the > Protection of Human Rights and Fundamental Freedoms. > >
