[Xen-changelog] [xen stable-4.4] x86: tolerate running on EFI runtime services page tables in map_domain_page()

[patchbot@xxxxxxx]

commit 62569eb8ce837cb548410b94bf2f8c16f3d0d2c9
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Nov 13 09:45:42 2014 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Nov 13 09:45:42 2014 +0100

    x86: tolerate running on EFI runtime services page tables in 
map_domain_page()
    
    In the event of a #PF while in an EFI runtime service function we
    otherwise can't dump the page tables, making the analysis of the
    problem more cumbersome.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: e65436ba36be8f1b735573d8fc9af7d8a053ba5f
    master date: 2014-10-27 16:43:12 +0100
---
 xen/arch/x86/domain_page.c |    6 +++++-
 xen/arch/x86/efi/runtime.c |    5 +++++
 xen/arch/x86/efi/stub.c    |    6 ++++++
 xen/include/xen/efi.h      |    1 +
 4 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/domain_page.c b/xen/arch/x86/domain_page.c
index 3903952..158a164 100644
--- a/xen/arch/x86/domain_page.c
+++ b/xen/arch/x86/domain_page.c
@@ -7,6 +7,7 @@
  */
 
 #include <xen/domain_page.h>
+#include <xen/efi.h>
 #include <xen/mm.h>
 #include <xen/perfc.h>
 #include <xen/pfn.h>
@@ -37,11 +38,14 @@ static inline struct vcpu *mapcache_current_vcpu(void)
      */
     if ( unlikely(pagetable_is_null(v->arch.guest_table)) && is_pv_vcpu(v) )
     {
+        unsigned long cr3;
+
         /* If we really are idling, perform lazy context switch now. */
         if ( (v = idle_vcpu[smp_processor_id()]) == current )
             sync_local_execstate();
         /* We must now be running on the idle page table. */
-        ASSERT(read_cr3() == __pa(idle_pg_table));
+        ASSERT((cr3 = read_cr3()) == __pa(idle_pg_table) ||
+               (efi_enabled && cr3 == efi_rs_page_table()));
     }
 
     return v;
diff --git a/xen/arch/x86/efi/runtime.c b/xen/arch/x86/efi/runtime.c
index 166852d..1a57526 100644
--- a/xen/arch/x86/efi/runtime.c
+++ b/xen/arch/x86/efi/runtime.c
@@ -93,6 +93,11 @@ void efi_rs_leave(unsigned long cr3)
     stts();
 }
 
+paddr_t efi_rs_page_table(void)
+{
+    return virt_to_maddr(efi_l4_pgtable);
+}
+
 unsigned long efi_get_time(void)
 {
     EFI_TIME time;
diff --git a/xen/arch/x86/efi/stub.c b/xen/arch/x86/efi/stub.c
index 8916a2e..b8f49f8 100644
--- a/xen/arch/x86/efi/stub.c
+++ b/xen/arch/x86/efi/stub.c
@@ -9,6 +9,12 @@ const bool_t efi_enabled = 0;
 
 void __init efi_init_memory(void) { }
 
+paddr_t efi_rs_page_table(void)
+{
+    BUG();
+    return 0;
+}
+
 unsigned long efi_get_time(void)
 {
     BUG();
diff --git a/xen/include/xen/efi.h b/xen/include/xen/efi.h
index 8a2b788..5e02724 100644
--- a/xen/include/xen/efi.h
+++ b/xen/include/xen/efi.h
@@ -28,6 +28,7 @@ struct xenpf_efi_runtime_call;
 struct compat_pf_efi_runtime_call;
 
 void efi_init_memory(void);
+paddr_t efi_rs_page_table(void);
 unsigned long efi_get_time(void);
 void efi_halt_system(void);
 void efi_reset_system(bool_t warm);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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