1 files changed, 22 insertions, 14 deletions

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index db832fd65ec..13ee258442a 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -71,7 +71,8 @@
 #include <asm/stackprotector.h>
 #include <asm/reboot.h>         /* for struct machine_ops */
 
-/*G:010 Welcome to the Guest!
+/*G:010
+ * Welcome to the Guest!
  *
  * The Guest in our tale is a simple creature: identical to the Host but
  * behaving in simplified but equivalent ways.  In particular, the Guest is the
@@ -190,15 +191,23 @@ static void lazy_hcall4(unsigned long call,
 #endif
 
 /*G:036
- * When lazy mode is turned off reset the per-cpu lazy mode variable and then
- * issue the do-nothing hypercall to flush any stored calls.
-:*/
+ * When lazy mode is turned off, we issue the do-nothing hypercall to
+ * flush any stored calls, and call the generic helper to reset the
+ * per-cpu lazy mode variable.
+ */
 static void lguest_leave_lazy_mmu_mode(void)
 {
         hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
         paravirt_leave_lazy_mmu();
 }
 
+/*
+ * We also catch the end of context switch; we enter lazy mode for much of
+ * that too, so again we need to flush here.
+ *
+ * (Technically, this is lazy CPU mode, and normally we're in lazy MMU
+ * mode, but unlike Xen, lguest doesn't care about the difference).
+ */
 static void lguest_end_context_switch(struct task_struct *next)
 {
         hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0);
@@ -391,7 +400,7 @@ static void lguest_load_tr_desc(void)
  * giant ball of hair.  Its entry in the current Intel manual runs to 28 pages.
  *
  * This instruction even it has its own Wikipedia entry.  The Wikipedia entry
- * has been translated into 5 languages.  I am not making this up!
+ * has been translated into 6 languages.  I am not making this up!
  *
  * We could get funky here and identify ourselves as "GenuineLguest", but
  * instead we just use the real "cpuid" instruction.  Then I pretty much turned
@@ -458,7 +467,7 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
         /*
          * PAE systems can mark pages as non-executable.  Linux calls this the
          * NX bit.  Intel calls it XD (eXecute Disable), AMD EVP (Enhanced
-         * Virus Protection).  We just switch turn if off here, since we don't
+         * Virus Protection).  We just switch it off here, since we don't
          * support it.
          */
         case 0x80000001:
@@ -520,17 +529,16 @@ static unsigned long lguest_read_cr2(void)
 
 /* See lguest_set_pte() below. */
 static bool cr3_changed = false;
+static unsigned long current_cr3;
 
 /*
  * cr3 is the current toplevel pagetable page: the principle is the same as
- * cr0.  Keep a local copy, and tell the Host when it changes.  The only
- * difference is that our local copy is in lguest_data because the Host needs
- * to set it upon our initial hypercall.
+ * cr0.  Keep a local copy, and tell the Host when it changes.
  */
 static void lguest_write_cr3(unsigned long cr3)
 {
-        lguest_data.pgdir = cr3;
         lazy_hcall1(LHCALL_NEW_PGTABLE, cr3);
+        current_cr3 = cr3;
 
         /* These two page tables are simple, linear, and used during boot */
         if (cr3 != __pa(swapper_pg_dir) && cr3 != __pa(initial_page_table))
@@ -539,7 +547,7 @@ static void lguest_write_cr3(unsigned long cr3)
 
 static unsigned long lguest_read_cr3(void)
 {
-        return lguest_data.pgdir;
+        return current_cr3;
 }
 
 /* cr4 is used to enable and disable PGE, but we don't care. */
@@ -641,7 +649,7 @@ static void lguest_write_cr4(unsigned long val)
 
 /*
  * The Guest calls this after it has set a second-level entry (pte), ie. to map
- * a page into a process' address space.  Wetell the Host the toplevel and
+ * a page into a process' address space.  We tell the Host the toplevel and
  * address this corresponds to.  The Guest uses one pagetable per process, so
  * we need to tell the Host which one we're changing (mm->pgd).
  */
@@ -758,7 +766,7 @@ static void lguest_pmd_clear(pmd_t *pmdp)
 static void lguest_flush_tlb_single(unsigned long addr)
 {
         /* Simply set it to zero: if it was not, it will fault back in. */
-        lazy_hcall3(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0);
+        lazy_hcall3(LHCALL_SET_PTE, current_cr3, addr, 0);
 }
 
 /*
@@ -1140,7 +1148,7 @@ static struct notifier_block paniced = {
 static __init char *lguest_memory_setup(void)
 {
         /*
-         *The Linux bootloader header contains an "e820" memory map: the
+         * The Linux bootloader header contains an "e820" memory map: the
          * Launcher populated the first entry with our memory limit.
          */
         e820_add_region(boot_params.e820_map[0].addr,