KVM: nSVM: Implement Enlightened MSR-Bitmap feature

Similar to nVMX commit 502d2bf5f2fd ("KVM: nVMX: Implement Enlightened MSR
Bitmap feature"), add support for the feature for nSVM (Hyper-V on KVM).

Notable differences from nVMX implementation:
- As the feature uses SW reserved fields in VMCB control, KVM needs to
make sure it's dealing with a Hyper-V guest (kvm_hv_hypercall_enabled()).

- 'msrpm_base_pa' needs to be always be overwritten in
nested_svm_vmrun_msrpm(), even when the update is skipped. As an
optimization, nested_vmcb02_prepare_control() copies it from VMCB01
so when MSR-Bitmap feature for L2 is disabled nothing needs to be done.

- 'struct vmcb_ctrl_area_cached' needs to be extended with clean
fields/sw reserved data and __nested_copy_vmcb_control_to_cache() needs to
copy it so nested_svm_vmrun_msrpm() can use it later.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220202095100.129834-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 365c17b9fe55..efcab4d2a062 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -137,6 +137,8 @@ struct vmcb_ctrl_area_cached {
 	u32 event_inj_err;
 	u64 nested_cr3;
 	u64 virt_ext;
+	u32 clean;
+	u8 reserved_sw[32];
 };
 
 struct svm_nested_state {