| Message ID | 20240608000639.3295768-1-seanjc@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: Register cpuhp/syscore callbacks when enabling virt | expand |
On Fri, 2024-06-07 at 17:06 -0700, 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. > > For this series, Acked-by: Kai Huang <kai.huang@intel.com>
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. 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