Merge branch 'kvm-late-6.1' into HEAD

[linux-block.git] / arch / x86 / kernel / cpu / mshyperv.c

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index e402923800d7aee9a94e2f686791bf7f338cb3d3..bfbdc072017db1bf8c678c548ebde7861958fc06 100644 (file)
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -475,6 +475,12 @@ static bool __init ms_hyperv_x2apic_available(void)
  * (logically) generates MSIs directly to the system APIC irq domain.
  * There is no HPET, and PCI MSI/MSI-X interrupts are remapped by the
  * pci-hyperv host bridge.
+ *
+ * Note: for a Hyper-V root partition, this will always return false.
+ * The hypervisor doesn't expose these HYPERV_CPUID_VIRT_STACK_* cpuids by
+ * default, they are implemented as intercepts by the Windows Hyper-V stack.
+ * Even a nested root partition (L2 root) will not get them because the
+ * nested (L1) hypervisor filters them out.
  */
 static bool __init ms_hyperv_msi_ext_dest_id(void)
 {