KVM: x86: add SMM to the MMU role, support SMRAM address space

This is now very simple to do.  The only interesting part is a simple
trick to find the right memslot in gfn_to_rmap, retrieving the address
space from the spte role word.  The same trick is used in the auditing
code.

The comment on top of union kvm_mmu_page_role has been stale forever,
so remove it.  Speaking of stale code, remove pad_for_nice_hex_output
too: it was splitting the "access" bitfield across two bytes and thus
had effectively turned into pad_for_ugly_hex_output.

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt
index c59bd9bc41ef..3a4d681c3e98 100644
--- a/Documentation/virtual/kvm/mmu.txt
+++ b/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.