[Xen-devel] [RFC PATCH 77/84] x86: properly (un)map pages in restore_all_guests.

[<hongyax@xxxxxxxxxx>]

From: Hongyan Xia <hongyax@xxxxxxxxxx>

Before, it assumed both cr3 could be accessed via a direct map. This is
no longer true. Also, this means we can remove a xenheap mapping hack
we introduced earlier when building the cr3 of dom0.

Signed-off-by: Hongyan Xia <hongyax@xxxxxxxxxx>
---
 xen/arch/x86/pv/dom0_build.c | 11 +++++------
 xen/arch/x86/x86_64/entry.S  | 32 +++++++++++++++++++++++++++++---
 2 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index 0ec30988b8..202edcaa17 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -623,9 +623,7 @@ int __init dom0_construct_pv(struct domain *d,
     if ( !is_pv_32bit_domain(d) )
     {
         maddr_to_page(mpt_alloc)->u.inuse.type_info = PGT_l4_page_table;
-        l4start = l4tab = __va(mpt_alloc);
-        map_pages_to_xen((unsigned long)l4start, maddr_to_mfn(mpt_alloc), 1,
-                PAGE_HYPERVISOR);
+        l4start = l4tab = map_xen_pagetable(maddr_to_mfn(mpt_alloc));
         mpt_alloc += PAGE_SIZE;
         clear_page(l4tab);
         init_xen_l4_slots(l4tab, _mfn(virt_to_mfn(l4start)),
@@ -635,9 +633,8 @@ int __init dom0_construct_pv(struct domain *d,
     else
     {
         /* Monitor table already created by switch_compat(). */
-        l4start = l4tab = __va(pagetable_get_paddr(v->arch.guest_table));
-        map_pages_to_xen((unsigned long)l4start,
-                pagetable_get_mfn(v->arch.guest_table), 1, PAGE_HYPERVISOR);
+        l4start = l4tab =
+                map_xen_pagetable(pagetable_get_mfn(v->arch.guest_table));
         /* See public/xen.h on why the following is needed. */
         maddr_to_page(mpt_alloc)->u.inuse.type_info = PGT_l3_page_table;
         l3start = map_xen_pagetable(maddr_to_mfn(mpt_alloc));
@@ -907,6 +904,8 @@ int __init dom0_construct_pv(struct domain *d,
         pv_shim_setup_dom(d, l4start, v_start, vxenstore_start, vconsole_start,
                           vphysmap_start, si);
 
+    UNMAP_XEN_PAGETABLE(l4start);
+
     if ( is_pv_32bit_domain(d) )
         xlat_start_info(si, pv_shim ? XLAT_start_info_console_domU
                                     : XLAT_start_info_console_dom0);
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 11385857fa..8ca9a8e0ea 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -150,11 +150,27 @@ restore_all_guest:
         je    .Lrag_copy_done
         movb  $0, STACK_CPUINFO_FIELD(root_pgt_changed)(%rdx)
         movabs $PADDR_MASK & PAGE_MASK, %rsi
-        movabs $DIRECTMAP_VIRT_START, %rcx
         and   %rsi, %rdi
         and   %r9, %rsi
-        add   %rcx, %rdi
-        add   %rcx, %rsi
+
+        /* Without a direct map, we have to map pages first before copying. */
+        /* FIXME: optimisations may be needed. */
+        pushq %r9
+        pushq %rdx
+        pushq %rax
+        pushq %rsi
+        shr   $PAGE_SHIFT, %rdi
+        callq map_xen_pagetable
+        popq  %rdi
+        pushq %rax
+        shr   $PAGE_SHIFT, %rdi
+        callq map_xen_pagetable
+        mov   %rax, %rsi
+        mov   0(%rsp), %rdi
+
+        /* %rsi and %rdi are on top the stack for unmapping. */
+        pushq %rsi
+
         mov   $ROOT_PAGETABLE_FIRST_XEN_SLOT, %ecx
         mov   root_table_offset(SH_LINEAR_PT_VIRT_START)*8(%rsi), %r8
         mov   %r8, root_table_offset(SH_LINEAR_PT_VIRT_START)*8(%rdi)
@@ -166,6 +182,16 @@ restore_all_guest:
         sub   $(ROOT_PAGETABLE_FIRST_XEN_SLOT - \
                 ROOT_PAGETABLE_LAST_XEN_SLOT - 1) * 8, %rdi
         rep movsq
+
+        /* Unmap the two pages. */
+        popq  %rdi
+        callq unmap_xen_pagetable
+        popq  %rdi
+        callq unmap_xen_pagetable
+        popq  %rax
+        popq  %rdx
+        popq  %r9
+
 .Lrag_copy_done:
         mov   %r9, STACK_CPUINFO_FIELD(xen_cr3)(%rdx)
         movb  $1, STACK_CPUINFO_FIELD(use_pv_cr3)(%rdx)
-- 
2.17.1


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