KVM: nSVM: Avoid clearing VMCB_LBR in vmcb12

svm_copy_lbrs() always marks VMCB_LBR dirty in the destination VMCB.
However, nested_svm_vmexit() uses it to copy LBRs to vmcb12, and
clearing clean bits in vmcb12 is not architecturally defined.

Move vmcb_mark_dirty() to callers and drop it for vmcb12.

This also facilitates incoming refactoring that does not pass the entire
VMCB to svm_copy_lbrs().

Fixes: d20c796ca370 ("KVM: x86: nSVM: implement nested LBR virtualization")
Cc: stable@vger.kernel.org
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260303003421.2185681-2-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 3e2841598a36c4a6faf0883e0b7c342626d29852..0a35c815f4d2668475189d91ef1c8bf6f0a10172 100644 (file)
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -715,6 +715,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
        } else {
                svm_copy_lbrs(vmcb02, vmcb01);
        }
+       vmcb_mark_dirty(vmcb02, VMCB_LBR);
        svm_update_lbrv(&svm->vcpu);
 }
 
@@ -1231,10 +1232,12 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
                kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
 
        if (unlikely(guest_cpu_cap_has(vcpu, X86_FEATURE_LBRV) &&
-                    (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK)))
+                    (svm->nested.ctl.virt_ext & LBR_CTL_ENABLE_MASK))) {
                svm_copy_lbrs(vmcb12, vmcb02);
-       else
+       } else {
                svm_copy_lbrs(vmcb01, vmcb02);
+               vmcb_mark_dirty(vmcb01, VMCB_LBR);
+       }
 
        svm_update_lbrv(vcpu);
 

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 543f9f3f966e3925ea42c84610b6c404ef095158..9b4f5a46d55061f15fb3d0ae9f5a1b163644edde 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -848,8 +848,6 @@ void svm_copy_lbrs(struct vmcb *to_vmcb, struct vmcb *from_vmcb)
        to_vmcb->save.br_to             = from_vmcb->save.br_to;
        to_vmcb->save.last_excp_from    = from_vmcb->save.last_excp_from;
        to_vmcb->save.last_excp_to      = from_vmcb->save.last_excp_to;
-
-       vmcb_mark_dirty(to_vmcb, VMCB_LBR);
 }
 
 static void __svm_enable_lbrv(struct kvm_vcpu *vcpu)