On Wed, 2019-01-23 at 21:26 +1100, Paul Mackerras wrote: > If H_INT_ESB is only used for LSIs, then is a guest going to be using > it at all? *emulated* LSIs, ie LSIs coming from emulated devices. It will depends in practice of what kind of emulated device you put in your guest. We need that because under the hood, we send a XIVE MSI, so we need to be notified of the EOI so we can resend if the emulated LSI is still asserted. > My understanding was that with XIVE, only a small number > of interrupts that are to do with system management functions are > LSIs; all of the interrupts relating to PCI-e devices are MSIs. So do > we actually have a real high-frequency use case for LSIs in a guest? > > For now I would prefer that you remove all the real-mode hcall > handlers. We can add them later if we get performance data showing > that they are needed. > > Regarding whether or not to have a given hcall handler in the kernel > at all - if there is for example an hcall which is just called once > on guest startup, and its function is just to provide information to > the guest, and QEMU has that information, then why not have that hcall > implemented by QEMU? Are any of the hcalls like that? > > For example, if H_INT_GET_SOURCE_INFO was implemented in QEMU, could > we then remove the VC_BASE thing from the xive device? Ben.
