[PATCH v6 42/44] KVM: VMX: Dedup code for adding MSR to VMCS's auto list

Sean Christopherson
2025-12-06T00:18:51Z

Add a helper to add an MSR to a VMCS's "auto" list to deduplicate the code
in add_atomic_switch_msr(), and so that the functionality can be used in
the future for managing the MSR auto-store list.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/vmx.c | 41 +++++++++++++++++++----------------------
1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 018e01daab68..3f64d4b1b19c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1093,12 +1093,28 @@ static __always_inline void add_atomic_switch_msr_special(struct vcpu_vmx *vmx,
vm_exit_controls_setbit(vmx, exit);
}

+static void vmx_add_auto_msr(struct vmx_msrs *m, u32 msr, u64 value,
+ unsigned long vmcs_count_field, struct kvm *kvm)
+{
+ int i;
+
+ i = vmx_find_loadstore_msr_slot(m, msr);
+ if (i < 0) {
+ if (KVM_BUG_ON(m->nr == MAX_NR_LOADSTORE_MSRS, kvm))
+ return;
+
+ i = m->nr++;
+ m->val[i].index = msr;
+ vmcs_write32(vmcs_count_field, m->nr);
+ }
+ m->val[i].value = value;
+}
+
static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr,
u64 guest_val, u64 host_val)
{
struct msr_autoload *m = &vmx->msr_autoload;
struct kvm *kvm = vmx->vcpu.kvm;
- int i;

switch (msr) {
case MSR_EFER:
@@ -1132,27 +1148,8 @@ static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr,
wrmsrq(MSR_IA32_PEBS_ENABLE, 0);
}

- i = vmx_find_loadstore_msr_slot(&m->guest, msr);
- if (i < 0) {
- if (KVM_BUG_ON(m->guest.nr == MAX_NR_LOADSTORE_MSRS, kvm))
- return;
-
- i = m->guest.nr++;
- m->guest.val[i].index = msr;
- vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->guest.nr);
- }
- m->guest.val[i].value = guest_val;
-
- i = vmx_find_loadstore_msr_slot(&m->host, msr);
- if (i < 0) {
- if (KVM_BUG_ON(m->host.nr == MAX_NR_LOADSTORE_MSRS, kvm))
- return;
-
- i = m->host.nr++;
- m->host.val[i].index = msr;
- vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->host.nr);
- }
- m->host.val[i].value = host_val;
+ vmx_add_auto_msr(&m->guest, msr, guest_val, VM_ENTRY_MSR_LOAD_COUNT, kvm);
+ vmx_add_auto_msr(&m->guest, msr, host_val, VM_EXIT_MSR_LOAD_COUNT, kvm);
}

static bool update_transition_efer(struct vcpu_vmx *vmx)
--
2.52.0.223.gf5cc29aaa4-goog