Hi John, On Wed, Aug 20, 2014 at 8:31 AM, John Baldwin <j...@freebsd.org> wrote: > On Wednesday, August 20, 2014 9:31:54 am Roger Pau Monné wrote: >> On 20/08/14 11:19, Wei Hu wrote: >> > Hello, >> > >> > Sending to Xen, drivers and virtualization mailing lists since this might > be of interest to the folks on these aliases. >> > >> > I am working for Microsoft to improve the performance of FreeBSD running > on Hyper-V. Right now I am adding a feature in the vmbus driver which could > handle the host-guest channel communications on all vCPUs simultaneously. In > order to achieve this, the hypervisor will send same interrupt concurrently on > all the vCPUs. The traditional way on FreeBSD to set up interrupt handling for > devicse, such as calling bus_alloc_resource() to reserve an IRQ line, and then > calling bus_setup_intr() to create a vector, doesn't seem to work in this > case. It seems if the interrupt is routed via legacy IRQ, it can only be > active on one vCPU at a time. In order to allow the same interrupt to be > handled on all vCPUs concurrently, all I need is an IDT entry, not an IRQ > line. >> > >> > I checked current FreeBSD code. It looks to me Xen directly uses the > vector number IDT_EVTCHN (0x93) to achieve the same purpose. I am proposing > both Xen and Hyper-V share this same vector. Following is a little bit detail > of my proposal for the changes in the current kernel. >> > >> > >> > 1. In machdep.c: >> > >> > #ifdef XENHVM >> > >> > setidt(IDT_EVTCHN, &IDTVEC(xen_intr_upcall), SDT_SYSIGT, SEL_UPL, > 0); >> > >> > #else >> > >> > setidt(IDT_EVTCHN, &IDTVEC(hv_vmbus_intr), SDT_SYSIGT, SEL_UPL, > 0); >> > >> > #endif >> > >> > 2. Apic_vector.S >> > >> > Add IDTVEC(hv_vmbus_intr) to call Hyper-V vmbus interrupt service routine. >> > >> > Any thoughts, objections and feedbacks are all welcome. >> >> Hello, >> >> I don't think using the same IDT vector is the right approach, I would >> just pick a different IDT vector and use that for Hyper-V. Using the >> same IDT vector (like your suggestion above) would prevent shipping a >> kernel with with both Hyper-V and Xen support (like it's done now in >> GENERIC). >> >> Roger. > > Hmm, can't you make this a runtime check to only call setidt() if you detect > you are under the appropriate hypervisor? > > Also, bhyve currently has a hackish way of requesting a free IDT slot. > Perhaps it would be best if I added little API to reserve an IDT slot assuming > that callers could accept a dynamic IDT vector rather than a static one. >
Yup, it'll be good to get rid of vmm_ipi.c. best Neel > -- > John Baldwin > _______________________________________________ > freebsd-virtualizat...@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > To unsubscribe, send any mail to > "freebsd-virtualization-unsubscr...@freebsd.org" _______________________________________________ freebsd-xen@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-xen To unsubscribe, send any mail to "freebsd-xen-unsubscr...@freebsd.org"
