Re: PATCH: setup_vmcs_config: disable TSC scaling on unlike processors

[Don Bowman <db@donbowman.ca>]

OK, based on previous feedback, this patch version simply ignores any
inconsistency if a knowing and trusting user wishes.

In my case, two identical processors in stepping and version and all
others have 1 flag missing (retail vs tray version of chip), but the
next person might have another flag.

Comments?

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5382b82..264870e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -103,6 +103,9 @@ module_param_named(enable_shadow_vmcs,
enable_shadow_vmcs, bool, S_IRUGO);
 static bool __read_mostly nested = 0;
 module_param(nested, bool, S_IRUGO);

+static bool __read_mostly ignore_inconsistency = false;
+module_param(ignore_inconsistency, bool, S_IRUGO);
+
 static u64 __read_mostly host_xss;

 static bool __read_mostly enable_pml = 1;
@@ -3449,6 +3452,7 @@ static __init int setup_vmcs_config(struct
vmcs_config *vmcs_conf)
        vmcs_conf->pin_based_exec_ctrl = _pin_based_exec_control;
        vmcs_conf->cpu_based_exec_ctrl = _cpu_based_exec_control;
        vmcs_conf->cpu_based_2nd_exec_ctrl = _cpu_based_2nd_exec_control;
+       vmcs_conf->cpu_based_2nd_exec_ctrl &= ~SECONDARY_EXEC_TSC_SCALING;
        vmcs_conf->vmexit_ctrl         = _vmexit_control;
        vmcs_conf->vmentry_ctrl        = _vmentry_control;

@@ -9202,9 +9206,11 @@ static void __init vmx_check_processor_compat(void *rtn)
        if (setup_vmcs_config(&vmcs_conf) < 0)
                *(int *)rtn = -EIO;
        if (memcmp(&vmcs_config, &vmcs_conf, sizeof(struct vmcs_config)) != 0) {
-               printk(KERN_ERR "kvm: CPU %d feature inconsistency!\n",
-                               smp_processor_id());
-               *(int *)rtn = -EIO;
+               printk(KERN_ERR "kvm: CPU %d feature inconsistency%s!\n",
+                               smp_processor_id(),
+                               ignore_inconsistency ? " -- ignored" : "");
+               if (!ignore_inconsistency)
+                       *(int *)rtn = -EIO;
        }
 }