diff options
| author | Kirill A. Shutemov <[email protected]> | 2019-02-06 14:52:53 +0300 |
|---|---|---|
| committer | Borislav Petkov <[email protected]> | 2019-02-06 18:56:18 +0100 |
| commit | 45b13b424faafb81c8c44541f093a682fdabdefc (patch) | |
| tree | bfe1aa77e018ab73e84ef5e0eeb560d4e4d05adc | |
| parent | d28af26faa0b1daf3c692603d46bc4687c16f19e (diff) | |
x86/boot/compressed/64: Do not corrupt EDX on EFER.LME=1 setting
RDMSR in the trampoline code overwrites EDX but that register is used
to indicate whether 5-level paging has to be enabled and if clobbered,
leads to failure to boot on a 5-level paging machine.
Preserve EDX on the stack while we are dealing with EFER.
Fixes: b677dfae5aa1 ("x86/boot/compressed/64: Set EFER.LME=1 in 32-bit trampoline before returning to long mode")
Reported-by: Kyle D Pelton <[email protected]>
Signed-off-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: [email protected]
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Wei Huang <[email protected]>
Cc: x86-ml <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index f105ae8651c9..f62e347862cc 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -602,10 +602,12 @@ ENTRY(trampoline_32bit_src) 3: /* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */ pushl %ecx + pushl %edx movl $MSR_EFER, %ecx rdmsr btsl $_EFER_LME, %eax wrmsr + popl %edx popl %ecx /* Enable PAE and LA57 (if required) paging modes */ |