These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / Documentation / virtual / kvm / mmu.txt

diff --git a/kernel/Documentation/virtual/kvm/mmu.txt b/kernel/Documentation/virtual/kvm/mmu.txt
index c59bd9b..b653641 100644 (file)
--- a/kernel/Documentation/virtual/kvm/mmu.txt
+++ b/kernel/Documentation/virtual/kvm/mmu.txt
@@ -173,6 +173,12 @@ Shadow pages contain the following information:
     Contains the value of cr4.smap && !cr0.wp for which the page is valid
     (pages for which this is true are different from other pages; see the
     treatment of cr0.wp=0 below).
+  role.smm:
+    Is 1 if the page is valid in system management mode.  This field
+    determines which of the kvm_memslots array was used to build this
+    shadow page; it is also used to go back from a struct kvm_mmu_page
+    to a memslot, through the kvm_memslots_for_spte_role macro and
+    __gfn_to_memslot.
   gfn:
     Either the guest page table containing the translations shadowed by this
     page, or the base page frame for linear translations.  See role.direct.
@@ -352,7 +358,8 @@ In the first case there are two additional complications:
 - if CR4.SMEP is enabled: since we've turned the page into a kernel page,
   the kernel may now execute it.  We handle this by also setting spte.nx.
   If we get a user fetch or read fault, we'll change spte.u=1 and
-  spte.nx=gpte.nx back.
+  spte.nx=gpte.nx back.  For this to work, KVM forces EFER.NX to 1 when
+  shadow paging is in use.
 - if CR4.SMAP is disabled: since the page has been changed to a kernel
   page, it can not be reused when CR4.SMAP is enabled. We set
   CR4.SMAP && !CR0.WP into shadow page's role to avoid this case. Note,