Excerpts from Paul Mackerras's message of April 1, 2021 3:41 pm: > On Tue, Mar 23, 2021 at 11:02:34AM +1000, Nicholas Piggin wrote: >> System calls / hcalls have a different calling convention than >> other interrupts, so there is code in the KVMTEST to massage these >> into the same form as other interrupt handlers. >> >> Move this work into the KVM hcall handler. This means teaching KVM >> a little more about the low level interrupt handler setup, PACA save >> areas, etc., although that's not obviously worse than the current >> approach of coming up with an entirely different interrupt register >> / save convention. > > [snip] > >> @@ -1964,29 +1948,8 @@ EXC_VIRT_END(system_call, 0x4c00, 0x100) >> >> #ifdef CONFIG_KVM_BOOK3S_64_HANDLER >> TRAMP_REAL_BEGIN(system_call_kvm) >> - /* >> - * This is a hcall, so register convention is as above, with these >> - * differences: > > I haven't checked all the code changes in detail yet, but this comment > at least is slightly misleading, since under PR KVM, system calls (to > the guest kernel) and hypercalls both come through this path. Yeah good point, I'll update the comment at its destination. Thanks, Nick
