linux

iv/linux

History

Paolo Bonzini c822a075ab 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.
 -----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.

2024-03-18 19:03:42 -04:00

arm

KVM: arm64: Document vCPU feature selection UAPIs

2023-10-04 17:11:51 +00:00

devices

KVM: arm64: Clarify the ordering requirements for vcpu/RD creation

2023-09-30 18:15:44 +00:00

s390

ARM:

2022-08-04 14:59:54 -07:00

x86

KVM: x86: Improve documentation of MSR_KVM_ASYNC_PF_EN