linux

iv/linux

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Chao Gao e4aa7f88af KVM: Disable CPU hotplug during hardware enabling/disabling

Disable CPU hotplug when enabling/disabling hardware to prevent the
corner case where if the following sequence occurs:

  1. A hotplugged CPU marks itself online in cpu_online_mask
  2. The hotplugged CPU enables interrupt before invoking KVM's ONLINE
     callback
  3  hardware_{en,dis}able_all() is invoked on another CPU

the hotplugged CPU will be included in on_each_cpu() and thus get sent
through hardware_{en,dis}able_nolock() before kvm_online_cpu() is called.

        start_secondary { ...
                set_cpu_online(smp_processor_id(), true); <- 1
                ...
                local_irq_enable();  <- 2
                ...
                cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); <- 3
        }

KVM currently fudges around this race by keeping track of which CPUs have
done hardware enabling (see commit 1b6c016818a5 "KVM: Keep track of which
cpus have virtualization enabled"), but that's an inefficient, convoluted,
and hacky solution.

Signed-off-by: Chao Gao <chao.gao@intel.com>
[sean: split to separate patch, write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221130230934.1014142-43-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2022-12-29 15:48:32 -05:00

alpha

MM patches for 6.2-rc1.

2022-12-13 19:29:45 -08:00

arc

MM patches for 6.2-rc1.

2022-12-13 19:29:45 -08:00

arm

ARM: SoC fixes for 6.2

2022-12-19 16:07:59 -06:00

arm64

KVM: x86: Unify pr_fmt to use module name for all KVM modules