c822a075ab
Delete kvm_vcpu_pv_apf_data.enabled to fix a goof in KVM's async #PF ABI where the enabled field pushes the size of "struct kvm_vcpu_pv_apf_data" from 64 to 68 bytes, i.e. beyond a single cache line. The enabled field is purely a guest-side flag that Linux-as-a-guest uses to track whether or not the guest has enabled async #PF support. The actual flag that is passed to the host, i.e. to KVM proper, is a single bit in a synthetic MSR, MSR_KVM_ASYNC_PF_EN, i.e. is in a location completely unrelated to the shared kvm_vcpu_pv_apf_data structure. Simply drop the the field and use a dedicated guest-side per-CPU variable to fix the ABI, as opposed to fixing the documentation to match reality. KVM has never consumed kvm_vcpu_pv_apf_data.enabled, so the odds of the ABI change breaking anything are extremely low. -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEKTobbabEP7vbhhN9OlYIJqCjN/0FAmXZBsMACgkQOlYIJqCj N/1H5g/8CgK81MpaTI4CsCf0rwD4orhmghAnJmllJHi676dteUm7gYzbDE8wajym rS7gtJwqe6cnK7hJt7SH31sfDEhYds43wD7o6VrLewjWCgaZ7YilYb+qJhzGOUt5 OxQwzZu/57hOhXFFS7P7ZamgkiQu05IYLuK5BSWQbsuMLaGkA+uWoNKopr5588VW MQhR4jVCQSEdgYakgpy+TjWVi4/usiHHCFhcGV54ErKAKL/nCjyUOrgApINTzawQ Czh3ZAKMo6UanHOB6lZACc3MdSOTooDnIItzWOFDMJSLW376tmC70OGI42qi3ht6 CB5zoUN9p4WyQkb7BluJ40PTmpNPEQQVglmU0bjVAKuGmDZ6YgkQ1OWAap6mH+q1 JOzuFgXMXP+aCYXfeZYHedmPsqW+BJ4dd9vOtnoFE7sgCMye26gFb45wbuTWPFpX LcjykG6YUJJI/LcIc3i68onHPn7RI9XXOIVCyAh39zclCPkIKrlI8RKMlg2yBIdv pkLYHUsXRJ+02GHd7YQGFe6ph1rHs3P5LsNoUh8cLetGharww2fqpuAVDwftMvAg MG3zgA6BGv4bpHDNjGPEh+3g36d9C6hOheek2Wgjwy7zF6JxQme4UsXzecqETT5o j7LxLfjUaPzAvfTlGA9jZYO3X7tqpJomj1YxQQEd2p/36nGR+3k= =3ujw -----END PGP SIGNATURE----- Merge tag 'kvm-x86-asyncpf_abi-6.9' of https://github.com/kvm-x86/linux into HEAD Guest-side KVM async #PF ABI cleanup for 6.9 Delete kvm_vcpu_pv_apf_data.enabled to fix a goof in KVM's async #PF ABI where the enabled field pushes the size of "struct kvm_vcpu_pv_apf_data" from 64 to 68 bytes, i.e. beyond a single cache line. The enabled field is purely a guest-side flag that Linux-as-a-guest uses to track whether or not the guest has enabled async #PF support. The actual flag that is passed to the host, i.e. to KVM proper, is a single bit in a synthetic MSR, MSR_KVM_ASYNC_PF_EN, i.e. is in a location completely unrelated to the shared kvm_vcpu_pv_apf_data structure. Simply drop the the field and use a dedicated guest-side per-CPU variable to fix the ABI, as opposed to fixing the documentation to match reality. KVM has never consumed kvm_vcpu_pv_apf_data.enabled, so the odds of the ABI change breaking anything are extremely low. |
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