[Xen-devel] [RFC PATCH 72/84] acpi: don't assume an always-mapped direct map in acpi allocations.

[<hongyax@xxxxxxxxxx>]

From: Hongyan Xia <hongyax@xxxxxxxxxx>

Signed-off-by: Hongyan Xia <hongyax@xxxxxxxxxx>
---
 xen/drivers/acpi/osl.c | 41 +++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/xen/drivers/acpi/osl.c b/xen/drivers/acpi/osl.c
index 4c8bb7839e..dbf62325f3 100644
--- a/xen/drivers/acpi/osl.c
+++ b/xen/drivers/acpi/osl.c
@@ -216,14 +216,25 @@ acpi_os_write_memory(acpi_physical_address phys_addr, u32 
value, u32 width)
 
 void *__init acpi_os_alloc_memory(size_t sz)
 {
-       void *ptr;
-
-       if (system_state == SYS_STATE_early_boot)
-               return mfn_to_virt(mfn_x(alloc_boot_pages(PFN_UP(sz), 1)));
-
-       ptr = xmalloc_bytes(sz);
-       ASSERT(!ptr || is_xmalloc_memory(ptr));
-       return ptr;
+    void *ptr;
+    unsigned long nr_pfns = PFN_UP(sz);
+    mfn_t mfn;
+
+    if (system_state == SYS_STATE_early_boot)
+    {
+        mfn = alloc_boot_pages(nr_pfns, 1);
+        ptr = mfn_to_virt(mfn_x(mfn));
+        /*
+         * Direct map is garbage now, fill the actual mapping. Safe to do so
+         * now because map_pages got rid of the direct map even in early boot.
+         */
+        map_pages_to_xen((unsigned long)ptr, mfn, nr_pfns, PAGE_HYPERVISOR);
+        return ptr;
+    }
+
+    ptr = xmalloc_bytes(sz);
+    ASSERT(!ptr || is_xmalloc_memory(ptr));
+    return ptr;
 }
 
 void *__init acpi_os_zalloc_memory(size_t sz)
@@ -241,8 +252,14 @@ void *__init acpi_os_zalloc_memory(size_t sz)
 
 void __init acpi_os_free_memory(void *ptr)
 {
-       if (is_xmalloc_memory(ptr))
-               xfree(ptr);
-       else if (ptr && system_state == SYS_STATE_early_boot)
-               init_boot_pages(__pa(ptr), __pa(ptr) + PAGE_SIZE);
+    mfn_t mfn;
+    if (is_xmalloc_memory(ptr))
+        xfree(ptr);
+    else if (ptr && system_state == SYS_STATE_early_boot)
+    {
+        init_boot_pages(__pa(ptr), __pa(ptr) + PAGE_SIZE);
+        /* Also unmap in the 1:1 region for security. */
+        mfn = _mfn(virt_to_mfn(ptr));
+        map_pages_to_xen((unsigned long)ptr, mfn, 1, _PAGE_NONE);
+    }
 }
-- 
2.17.1


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