lguest: PAE support

This version requires that host and guest have the same PAE status.
NX cap is not offered to the guest, yet.

Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 66 insertions, 6 deletions

diff --git a/arch/x86/lguest/Kconfig b/arch/x86/lguest/Kconfig
index 8dab8f7844d3..38718041efc3 100644
--- a/arch/x86/lguest/Kconfig
+++ b/arch/x86/lguest/Kconfig
@@ -2,7 +2,6 @@ config LGUEST_GUEST
         bool "Lguest guest support"
         select PARAVIRT
         depends on X86_32
-        depends on !X86_PAE
         select VIRTIO
         select VIRTIO_RING
         select VIRTIO_CONSOLE
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index d12f554e5f6a..7bc65f0f62c4 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -167,6 +167,7 @@ static void lazy_hcall3(unsigned long call,
                 async_hcall(call, arg1, arg2, arg3, 0);
 }
 
+#ifdef CONFIG_X86_PAE
 static void lazy_hcall4(unsigned long call,
                        unsigned long arg1,
                        unsigned long arg2,
@@ -178,6 +179,7 @@ static void lazy_hcall4(unsigned long call,
         else
                 async_hcall(call, arg1, arg2, arg3, arg4);
 }
+#endif
 
 /* 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. */
@@ -380,8 +382,8 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
         case 1: /* Basic feature request. */
                 /* We only allow kernel to see SSE3, CMPXCHG16B and SSSE3 */
                 *cx &= 0x00002201;
-                /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, TSC, FPU. */
-                *dx &= 0x07808111;
+                /* SSE, SSE2, FXSR, MMX, CMOV, CMPXCHG8B, TSC, FPU, PAE. */
+                *dx &= 0x07808151;
                 /* The Host can do a nice optimization if it knows that the
                  * kernel mappings (addresses above 0xC0000000 or whatever
                  * PAGE_OFFSET is set to) haven't changed.  But Linux calls
@@ -400,6 +402,11 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
                 if (*ax > 0x80000008)
                         *ax = 0x80000008;
                 break;
+        case 0x80000001:
+                /* Here we should fix nx cap depending on host. */
+                /* For this version of PAE, we just clear NX bit. */
+                *dx &= ~(1 << 20);
+                break;
         }
 }
 
@@ -533,7 +540,12 @@ static void lguest_write_cr4(unsigned long val)
 static void lguest_pte_update(struct mm_struct *mm, unsigned long addr,
                                pte_t *ptep)
 {
+#ifdef CONFIG_X86_PAE
+        lazy_hcall4(LHCALL_SET_PTE, __pa(mm->pgd), addr,
+                    ptep->pte_low, ptep->pte_high);
+#else
         lazy_hcall3(LHCALL_SET_PTE, __pa(mm->pgd), addr, ptep->pte_low);
+#endif
 }
 
 static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
@@ -543,15 +555,37 @@ static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
         lguest_pte_update(mm, addr, ptep);
 }
 
-/* The Guest calls this to set a top-level entry.  Again, we set the entry then
- * tell the Host which top-level page we changed, and the index of the entry we
- * changed. */
+/* The Guest calls lguest_set_pud to set a top-level entry and lguest_set_pmd
+ * to set a middle-level entry when PAE is activated.
+ * Again, we set the entry then tell the Host which page we changed,
+ * and the index of the entry we changed. */
+#ifdef CONFIG_X86_PAE
+static void lguest_set_pud(pud_t *pudp, pud_t pudval)
+{
+        native_set_pud(pudp, pudval);
+
+        /* 32 bytes aligned pdpt address and the index. */
+        lazy_hcall2(LHCALL_SET_PGD, __pa(pudp) & 0xFFFFFFE0,
+                   (__pa(pudp) & 0x1F) / sizeof(pud_t));
+}
+
+static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
+{
+        native_set_pmd(pmdp, pmdval);
+        lazy_hcall2(LHCALL_SET_PMD, __pa(pmdp) & PAGE_MASK,
+                   (__pa(pmdp) & (PAGE_SIZE - 1)) / sizeof(pmd_t));
+}
+#else
+
+/* The Guest calls lguest_set_pmd to set a top-level entry when PAE is not
+ * activated. */
 static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
 {
         native_set_pmd(pmdp, pmdval);
         lazy_hcall2(LHCALL_SET_PGD, __pa(pmdp) & PAGE_MASK,
                    (__pa(pmdp) & (PAGE_SIZE - 1)) / sizeof(pmd_t));
 }
+#endif
 
 /* There are a couple of legacy places where the kernel sets a PTE, but we
  * don't know the top level any more.  This is useless for us, since we don't
@@ -569,6 +603,26 @@ static void lguest_set_pte(pte_t *ptep, pte_t pteval)
                 lazy_hcall1(LHCALL_FLUSH_TLB, 1);
 }
 
+#ifdef CONFIG_X86_PAE
+static void lguest_set_pte_atomic(pte_t *ptep, pte_t pte)
+{
+        native_set_pte_atomic(ptep, pte);
+        if (cr3_changed)
+                lazy_hcall1(LHCALL_FLUSH_TLB, 1);
+}
+
+void lguest_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+        native_pte_clear(mm, addr, ptep);
+        lguest_pte_update(mm, addr, ptep);
+}
+
+void lguest_pmd_clear(pmd_t *pmdp)
+{
+        lguest_set_pmd(pmdp, __pmd(0));
+}
+#endif
+
 /* Unfortunately for Lguest, the pv_mmu_ops for page tables were based on
  * native page table operations.  On native hardware you can set a new page
  * table entry whenever you want, but if you want to remove one you have to do
@@ -1035,6 +1089,7 @@ __init void lguest_init(void)
         pv_info.name = "lguest";
         pv_info.paravirt_enabled = 1;
         pv_info.kernel_rpl = 1;
+        pv_info.shared_kernel_pmd = 1;
 
         /* We set up all the lguest overrides for sensitive operations.  These
          * are detailed with the operations themselves. */
@@ -1080,6 +1135,12 @@ __init void lguest_init(void)
         pv_mmu_ops.set_pte = lguest_set_pte;
         pv_mmu_ops.set_pte_at = lguest_set_pte_at;
         pv_mmu_ops.set_pmd = lguest_set_pmd;
+#ifdef CONFIG_X86_PAE
+        pv_mmu_ops.set_pte_atomic = lguest_set_pte_atomic;
+        pv_mmu_ops.pte_clear = lguest_pte_clear;
+        pv_mmu_ops.pmd_clear = lguest_pmd_clear;
+        pv_mmu_ops.set_pud = lguest_set_pud;
+#endif
         pv_mmu_ops.read_cr2 = lguest_read_cr2;
         pv_mmu_ops.read_cr3 = lguest_read_cr3;
         pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu;