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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen: do live patching only from main idle loop
On 3/2/20 2:28 PM, Jan Beulich wrote: > On 11.02.2020 10:31, Juergen Gross wrote: >> One of the main design goals of core scheduling is to avoid actions >> which are not directly related to the domain currently running on a >> given cpu or core. Live patching is one of those actions which are >> allowed taking place on a cpu only when the idle scheduling unit is >> active on that cpu. >> >> Unfortunately live patching tries to force the cpus into the idle loop >> just by raising the schedule softirq, which will no longer be >> guaranteed to work with core scheduling active. Additionally there are >> still some places in the hypervisor calling check_for_livepatch_work() >> without being in the idle loop. >> >> It is easy to force a cpu into the main idle loop by scheduling a >> tasklet on it. So switch live patching to use tasklets for switching to >> idle and raising scheduling events. Additionally the calls of >> check_for_livepatch_work() outside the main idle loop can be dropped. >> >> As tasklets are only running on idle vcpus and stop_machine_run() >> is activating tasklets on all cpus but the one it has been called on >> to rendezvous, it is mandatory for stop_machine_run() to be called on >> an idle vcpu, too, as otherwise there is no way for scheduling to >> activate the idle vcpu for the tasklet on the sibling of the cpu >> stop_machine_run() has been called on. >> >> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> >> --- >> xen/arch/arm/domain.c | 9 ++++----- >> xen/arch/arm/traps.c | 6 ------ >> xen/arch/x86/domain.c | 9 ++++----- >> xen/arch/x86/hvm/svm/svm.c | 2 +- >> xen/arch/x86/hvm/vmx/vmcs.c | 2 +- >> xen/arch/x86/pv/domain.c | 2 +- >> xen/arch/x86/setup.c | 2 +- >> xen/common/livepatch.c | 39 ++++++++++++++++++++++++++++++++++----- >> 8 files changed, 46 insertions(+), 25 deletions(-) > > Konrad, Ross - I was about to apply this when I noticed an ack > by one of the two of you is still needed. Care to provide one > (or comment if there are issues)? > Sorry. Reviewed-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx> _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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