[Xen-changelog] [xen staging] efi: optionally call SetVirtualAddressMap()

[patchbot@xxxxxxx]

commit 49450415d6ba646c34d62605457cff36bc4b52ed
Author:     Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
AuthorDate: Fri Oct 25 17:49:28 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Oct 25 17:49:28 2019 +0200

    efi: optionally call SetVirtualAddressMap()
    
    Some UEFI implementations are not happy about lack of
    SetVirtualAddressMap() call. Likely abuse the address map change
    notification to do things beyond the necessary ConvertPointer() calls.
    Specifically, wihtout the SetVirtualAddressMap() call, some access
    EfiBootServices{Code,Data}, or even totally unmapped areas. Example
    crash of GetVariable() call on Thinkpad W540:
    
        Xen call trace:
           [<0000000000000080>] 0000000000000080
           [<8c2b0398e0000daa>] 8c2b0398e0000daa
    
        Pagetable walk from ffffffff858483a1:
           L4[0x1ff] = 0000000000000000 ffffffffffffffff
    
        ****************************************
        Panic on CPU 0:
        FATAL PAGE FAULT
        [error_code=0002]
        Faulting linear address: ffffffff858483a1
        ****************************************
    
    Fix this by calling SetVirtualAddressMap() runtime service, giving it
    1:1 map for areas marked as needed during runtime. The address space in
    which EFI runtime services are called is unchanged, but UEFI view of it
    may be.
    Since it's fairly late in Xen 4.13 development cycle, disable it
    by default and hide behind EXPERT.
    
    Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Release-acked-by: Juergen Gross <jgross@xxxxxxxx>
---
 xen/common/Kconfig    | 10 ++++++++++
 xen/common/efi/boot.c | 33 ++++++++++++++++++++++++++++++---
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index 5c0f8d30c7..7fe538b027 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -115,6 +115,16 @@ config KEXEC
 
          If unsure, say Y.
 
+config EFI_SET_VIRTUAL_ADDRESS_MAP
+    bool "EFI: call SetVirtualAddressMap()" if EXPERT = "y"
+    ---help---
+      Call EFI SetVirtualAddressMap() runtime service to setup memory map for
+      further runtime services. According to UEFI spec, it isn't strictly
+      necessary, but many UEFI implementations misbehave when this call is
+      missing.
+
+      If unsure, say N.
+
 config XENOPROF
        def_bool y
        prompt "Xen Oprofile Support" if EXPERT = "y"
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 5473716a07..bbe80ec02d 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1060,11 +1060,17 @@ static void __init 
efi_set_gop_mode(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop, UINTN gop
         efi_arch_video_init(gop, info_size, mode_info);
 }
 
+#define INVALID_VIRTUAL_ADDRESS (0xBAAADUL << \
+                                 (EFI_PAGE_SHIFT + BITS_PER_LONG - 32))
+
 static void __init efi_exit_boot(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE 
*SystemTable)
 {
     EFI_STATUS status;
     UINTN info_size = 0, map_key;
     bool retry;
+#ifdef CONFIG_EFI_SET_VIRTUAL_ADDRESS_MAP
+    unsigned int i;
+#endif
 
     efi_bs->GetMemoryMap(&info_size, NULL, &map_key,
                          &efi_mdesc_size, &mdesc_ver);
@@ -1098,6 +1104,26 @@ static void __init efi_exit_boot(EFI_HANDLE ImageHandle, 
EFI_SYSTEM_TABLE *Syste
     if ( EFI_ERROR(status) )
         PrintErrMesg(L"Cannot exit boot services", status);
 
+#ifdef CONFIG_EFI_SET_VIRTUAL_ADDRESS_MAP
+    for ( i = 0; i < efi_memmap_size; i += efi_mdesc_size )
+    {
+        EFI_MEMORY_DESCRIPTOR *desc = efi_memmap + i;
+
+        if ( desc->Attribute & EFI_MEMORY_RUNTIME )
+            desc->VirtualStart = desc->PhysicalStart;
+        else
+            desc->VirtualStart = INVALID_VIRTUAL_ADDRESS;
+    }
+    status = efi_rs->SetVirtualAddressMap(efi_memmap_size, efi_mdesc_size,
+                                          mdesc_ver, efi_memmap);
+    if ( status != EFI_SUCCESS )
+    {
+        printk(XENLOG_ERR "EFI: SetVirtualAddressMap() failed (%#lx), 
disabling runtime services\n",
+               status);
+        __clear_bit(EFI_RS, &efi_flags);
+    }
+#endif
+
     /* Adjust pointers into EFI. */
     efi_ct = (void *)efi_ct + DIRECTMAP_VIRT_START;
     efi_memmap = (void *)efi_memmap + DIRECTMAP_VIRT_START;
@@ -1464,8 +1490,6 @@ static bool __init rt_range_valid(unsigned long smfn, 
unsigned long emfn)
     return true;
 }
 
-#define INVALID_VIRTUAL_ADDRESS (0xBAAADUL << \
-                                 (EFI_PAGE_SHIFT + BITS_PER_LONG - 32))
 
 void __init efi_init_memory(void)
 {
@@ -1580,7 +1604,10 @@ void __init efi_init_memory(void)
         return;
     }
 
-    /* Set up 1:1 page tables to do runtime calls in "physical" mode. */
+    /*
+     * Set up 1:1 page tables for runtime calls. See SetVirtualAddressMap() in
+     * efi_exit_boot().
+     */
     efi_l4_pgtable = alloc_xen_pagetable();
     BUG_ON(!efi_l4_pgtable);
     clear_page(efi_l4_pgtable);
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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