Re: [PATCH v19 070/130] KVM: TDX: TDP MMU TDX support

Chao Gao
2024-03-28T03:13:10Z

>+#if IS_ENABLED(CONFIG_HYPERV)
>+static int vt_flush_remote_tlbs(struct kvm *kvm);
>+#endif
>+
> static __init int vt_hardware_setup(void)
> {
> int ret;
>@@ -49,11 +53,29 @@ static __init int vt_hardware_setup(void)
> pr_warn_ratelimited("TDX requires mmio caching. Please enable mmio caching for TDX.\n");
> }
>
>+#if IS_ENABLED(CONFIG_HYPERV)
>+ /*
>+ * TDX KVM overrides flush_remote_tlbs method and assumes
>+ * flush_remote_tlbs_range = NULL that falls back to
>+ * flush_remote_tlbs. Disable TDX if there are conflicts.
>+ */
>+ if (vt_x86_ops.flush_remote_tlbs ||
>+ vt_x86_ops.flush_remote_tlbs_range) {
>+ enable_tdx = false;
>+ pr_warn_ratelimited("TDX requires baremetal. Not Supported on VMM guest.\n");
>+ }
>+#endif
>+
> enable_tdx = enable_tdx && !tdx_hardware_setup(&vt_x86_ops);
> if (enable_tdx)
> vt_x86_ops.vm_size = max_t(unsigned int, vt_x86_ops.vm_size,
> sizeof(struct kvm_tdx));
>
>+#if IS_ENABLED(CONFIG_HYPERV)
>+ if (enable_tdx)
>+ vt_x86_ops.flush_remote_tlbs = vt_flush_remote_tlbs;

Is this hook necessary/beneficial to TDX?

if no, we can leave .flush_remote_tlbs as NULL. if yes, we should do:

struct kvm_x86_ops {
...
#if IS_ENABLED(CONFIG_HYPERV) || IS_ENABLED(TDX...)
int (*flush_remote_tlbs)(struct kvm *kvm);
int (*flush_remote_tlbs_range)(struct kvm *kvm, gfn_t gfn,
gfn_t nr_pages);
#endif