[PATCH v5 0/3] KVM: SVM: Flush cache only on CPUs running SEV guest

Zheyun Shen
2025-01-20T12:13:04Z

Previous versions pointed out the problem of wbinvd_on_all_cpus() in SEV
and tried to maintain a cpumask to solve it. This version futher removes
unnecessary calls to wbinvd().

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.

---
v4 -> v5:
- Added a commit to remove unnecessary calls to wbinvd().

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 | 45 +++++++++++++++++++++++++++++++++---------
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, 50 insertions(+), 12 deletions(-)

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2.34.1