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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/8/24 02:06, Sean Christopherson wrote: > Register KVM's cpuhp and syscore callbacks when enabling virtualization in > hardware, as the sole purpose of said callbacks is to disable and re-enable > virtualization as needed. > > The primary motivation for this series is to simplify dealing with enabling > virtualization for Intel's TDX, which needs to enable virtualization > when kvm-intel.ko is loaded, i.e. long before the first VM is created. TDX > doesn't _need_ to keep virtualization enabled, but doing so is much simpler > for KVM (see patch 3). > > That said, this is a nice cleanup on its own, assuming I haven't broken > something. By registering the callbacks on-demand, the callbacks themselves > don't need to check kvm_usage_count, because their very existence implies a > non-zero count. > > The meat is in patch 1. Patches 2 renames the helpers so that patch 3 is > less awkward. Patch 3 adds a module param to enable virtualization when KVM > is loaded. Patches 4-6 are tangentially related x86 cleanups to registers > KVM's "emergency disable" callback on-demand, same as the syscore callbacks. > > The suspend/resume and cphup paths still need to be fully tested, as do > non-x86 architectures. Also placed in kvm/queue, mostly as a reminder to myself, and added other maintainers for testing on ARM, RISC-V and LoongArch. The changes from v3 to v4 should be mostly nits, documentation and organization of the series. Thanks, Paolo > v3: > - Collect reviews/acks. > - Switch to kvm_usage_lock in a dedicated patch, Cc'd for stable@. [Chao] > - Enable virt at load by default. [Chao] > - Add comments to document how kvm_arch_{en,dis}able_virtualization() fit > into the overall flow. [Kai] > > v2: > - https://lore.kernel.org/all/20240522022827.1690416-1-seanjc@google.com > - Use a dedicated mutex to avoid lock inversion issues between kvm_lock and > the cpuhp lock. > - Register emergency disable callbacks on-demand. [Kai] > - Drop an unintended s/junk/ign rename. [Kai] > - Decrement kvm_usage_count on failure. [Chao] > > v1: https://lore.kernel.org/all/20240425233951.3344485-1-seanjc@google.com > > Sean Christopherson (8): > KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock > KVM: Register cpuhp and syscore callbacks when enabling hardware > KVM: Rename functions related to enabling virtualization hardware > KVM: Add a module param to allow enabling virtualization when KVM is > loaded > KVM: Add arch hooks for enabling/disabling virtualization > x86/reboot: Unconditionally define cpu_emergency_virt_cb typedef > KVM: x86: Register "emergency disable" callbacks when virt is enabled > KVM: Enable virtualization at load/initialization by default > > Documentation/virt/kvm/locking.rst | 19 ++- > arch/x86/include/asm/kvm_host.h | 3 + > arch/x86/include/asm/reboot.h | 2 +- > arch/x86/kvm/svm/svm.c | 5 +- > arch/x86/kvm/vmx/main.c | 2 + > arch/x86/kvm/vmx/vmx.c | 6 +- > arch/x86/kvm/vmx/x86_ops.h | 1 + > arch/x86/kvm/x86.c | 10 ++ > include/linux/kvm_host.h | 14 ++ > virt/kvm/kvm_main.c | 258 ++++++++++++++--------------- > 10 files changed, 175 insertions(+), 145 deletions(-) > > > base-commit: af0903ab52ee6d6f0f63af67fa73d5eb00f79b9a