On Tue, 8 Oct 2019 at 13:27, Laszlo Ersek <ler...@redhat.com> wrote: > > Repo: https://github.com/lersek/edk2.git > Branch: max_cpus_bz_1515 > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1515 > > UefiCpuPkg/MpInitLib currently lacks support for the following use case: > > - time-limited AP enumeration is not reliable on the platform > (individual AP check-in may take arbitrarily long), and > > - APs may finish the wakeup routine, and report in to the BSP, in any > sequence whatsoever, and > > - the number of boot CPUs (which is known in advance) is strictly less > than the number of maximum CPUs (which is also known in advance). > > In the above case, the platform cannot tell UefiCpuPkg/MpInitLib to wait > exactly until all boot APs check in. That is, the platform can't request > that the AP enumeration never time out, but also not wait for too long. > > For supporting this use case, the patch series introduces > PcdCpuBootLogicalProcessorNumber to UefiCpuPkg, and makes MpInitLib wait > for exactly that many CPUs (= BSP + APs) to show up during CPU > enumeration. > > Working towards VCPU hotplug with OVMF, OvmfPkg/PlatformPei fetches both > the boot and the max CPU counts from QEMU, co-operating with the > following QEMU patch set: > > [qemu-devel] [PATCH 0/4] hw/i386: pass "MachineState.smp.max_cpus" to OVMF > http://mid.mail-archive.com/20191008105259.5378-1-lersek@redhat.com > > and passes them to UefiCpuPkg via PcdCpuBootLogicalProcessorNumber and > PcdCpuMaxLogicalProcessorNumber. > > As a result, PcdCpuApInitTimeOutInMicroSeconds becomes irrelevant for, > and unused by, OVMF -- time-limited AP enumeration is never going to be > used. > > When OVMF is built with -D SMM_REQUIRE, this patch series is just a > small building block, towards the full VCPU hotplug feature. However, > when OVMF is built without -D SMM_REQUIRE, this series (together with > the counterpart patch set for QEMU) completes the VCPU hotplug feature: > it allows S3 resume to work with VCPUs hot-plugged previously (at OS > runtime, of course). > > Cc: Anthony Perard <anthony.per...@citrix.com> > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > Cc: Eric Dong <eric.d...@intel.com> > Cc: Igor Mammedov <imamm...@redhat.com> > Cc: Jordan Justen <jordan.l.jus...@intel.com> > Cc: Julien Grall <julien.gr...@arm.com> > Cc: Ray Ni <ray...@intel.com> > > Thanks > Laszlo > > Laszlo Ersek (4): > UefiCpuPkg/MpInitLib: honor the platform's boot CPU count in AP > detection
Assuming this ^^^ patch gets accepted by the maintainers, > OvmfPkg/OvmfXen.dsc: remove PcdCpu* dynamic defaults > OvmfPkg/IndustryStandard: define FW_CFG_X86_TOPOLOGY structure type > OvmfPkg/PlatformPei: rewrite MaxCpuCountInitialization() for CPU > hotplug > Acked-by: Ard Biesheuvel <ard.biesheu...@linaro.org> for the OvmfPkg changes. -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#48567): https://edk2.groups.io/g/devel/message/48567 Mute This Topic: https://groups.io/mt/34441227/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
