[v7,0/3] KVM: SVM: Flush cache only on CPUs running SEV guest

Message

Zheyun Shen Jan. 28, 2025, 1:53 a.m. UTC

Previous versions pointed out the problem of wbinvd_on_all_cpus() in SEV
and tried to maintain a cpumask to solve it. This version includes
further code cleanup.

Although dirty_mask is not maintained perfectly and may lead to wbinvd on 
physical CPUs that are not running a SEV guest, it's still better than 
wbinvd_on_all_cpus(). And vcpu migration is designed to be solved in 
future work.

---
v6 -> v7:
- Fixed the writing oversight in sev_vcpu_load().

v5 -> v6:
- Replaced sev_get_wbinvd_dirty_mask() with the helper function 
to_kvm_sev_info().

v4 -> v5:
- rebase to tip @ 15e2f65f2ecf .
- Added a commit to remove unnecessary calls to wbinvd().
- Changed some comments.

v3 -> v4:
- Added a wbinvd helper and export it to SEV.
- Changed the struct cpumask in kvm_sev_info into cpumask*, which should
be dynamically allocated and freed.
- Changed the time of recording the CPUs from pre_sev_run() to vcpu_load().
- Removed code of clearing the mask.

v2 -> v3:
- Replaced get_cpu() with parameter cpu in pre_sev_run().

v1 -> v2:
- Added sev_do_wbinvd() to wrap two operations.
- Used cpumask_test_and_clear_cpu() to avoid concurrent problems.
---

Zheyun Shen (3):
  KVM: x86: Add a wbinvd helper
  KVM: SVM: Remove wbinvd in sev_vm_destroy()
  KVM: SVM: Flush cache only on CPUs running SEV guest

 arch/x86/kvm/svm/sev.c | 36 +++++++++++++++++++++++++++---------
 arch/x86/kvm/svm/svm.c |  2 ++
 arch/x86/kvm/svm/svm.h |  5 ++++-
 arch/x86/kvm/x86.c     |  9 +++++++--
 arch/x86/kvm/x86.h     |  1 +
 5 files changed, 41 insertions(+), 12 deletions(-)