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    SubjectRe: [PATCH 7/9] KVM, VMX: add support for switching of PERF_GLOBAL_CTRL
    On 10/03/2011 03:49 PM, Gleb Natapov wrote:
    > Some cpus have special support for switching PERF_GLOBAL_CTRL msr.
    > Add logic to detect if such support exists and works properly and extend
    > msr switching code to use it if available. Also extend number of generic
    > msr switching entries to 8.
    >
    >
    > static DECLARE_BITMAP(vmx_vpid_bitmap, VMX_NR_VPIDS);
    > static DEFINE_SPINLOCK(vmx_vpid_lock);
    > @@ -1195,10 +1196,29 @@ static void clear_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr)
    > {
    > unsigned i;
    > struct msr_autoload *m =&vmx->msr_autoload;
    > + u32 entry_load, exit_load;
    > + bool done = false;
    >
    > - if (msr == MSR_EFER&& cpu_has_load_ia32_efer) {
    > - vmcs_clear_bits(VM_ENTRY_CONTROLS, VM_ENTRY_LOAD_IA32_EFER);
    > - vmcs_clear_bits(VM_EXIT_CONTROLS, VM_EXIT_LOAD_IA32_EFER);
    > + switch (msr) {
    > + case MSR_EFER:
    > + if (cpu_has_load_ia32_efer) {
    > + entry_load = VM_ENTRY_LOAD_IA32_EFER;
    > + exit_load = VM_EXIT_LOAD_IA32_EFER;
    > + done = true;
    > + }
    > + break;
    > + case MSR_CORE_PERF_GLOBAL_CTRL:
    > + if (cpu_has_load_perf_global_ctrl) {
    > + entry_load = VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
    > + exit_load = VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
    > + done = true;
    > + }
    > + break;
    > + }
    > +
    > + if (done) {
    > + vmcs_clear_bits(VM_ENTRY_CONTROLS, entry_load);
    > + vmcs_clear_bits(VM_EXIT_CONTROLS, exit_load);
    > return;
    > }
    >
    >

    This is ugly. How about

    if (msr == MSR_EFER && cpu_has_load_ia32_efer) {
    clear_atomic_switch_msr_special(VM_ENTRY_LOAD_IA32_EFER,
    VM_EXIT_LOAD_IA32_EFER);
    return;
    }

    avoids the fake 'done' variable.

    --
    error compiling committee.c: too many arguments to function



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