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

Mi, Dapeng
2025-12-08T09:37:29Z

On 12/6/2025 8:17 AM, Sean Christopherson wrote:
> 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)

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>