KVM: MMU: Store nx bit for large page shadows

We need to distinguish between large page shadows which have the nx bit set
and those which don't.  The problem shows up when booting a newer smp Linux
kernel, where the trampoline page (which is in real mode, which uses the
same shadow pages as large pages) is using the same mapping as a kernel data
page, which is mapped using nx, causing kvm to spin on that page.

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index a7c5e6bee034e0b9d178f6cda5122756112d319b..65ab268d425609df2f38d18cf7eb9b87eb03d3da 100644 (file)
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -121,7 +121,7 @@ struct kvm_pte_chain {
  *   bits 4:7 - page table level for this shadow (1-4)
  *   bits 8:9 - page table quadrant for 2-level guests
  *   bit   16 - "metaphysical" - gfn is not a real page (huge page/real mode)
- *   bits 17:18 - "access" - the user and writable bits of a huge page pde
+ *   bits 17:19 - "access" - the user, writable, and nx bits of a huge page pde
  */
 union kvm_mmu_page_role {
        unsigned word;
@@ -131,7 +131,7 @@ union kvm_mmu_page_role {
                unsigned quadrant : 2;
                unsigned pad_for_nice_hex_output : 6;
                unsigned metaphysical : 1;
-               unsigned hugepage_access : 2;
+               unsigned hugepage_access : 3;
        };
 };
 

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index a7c5cb0319ea8ae70a18dce47b3c3cafe580662d..4b5391c717f8d4ddece1a84883cfb12b2efe3656 100644 (file)
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -366,6 +366,8 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
                        metaphysical = 1;
                        hugepage_access = *guest_ent;
                        hugepage_access &= PT_USER_MASK | PT_WRITABLE_MASK;
+                       if (*guest_ent & PT64_NX_MASK)
+                               hugepage_access |= (1 << 2);
                        hugepage_access >>= PT_WRITABLE_SHIFT;
                        table_gfn = (*guest_ent & PT_BASE_ADDR_MASK)
                                >> PAGE_SHIFT;