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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2019-02-06 14:52:53 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2019-02-06 18:56:18 +0100 |
| commit | 45b13b424faafb81c8c44541f093a682fdabdefc (patch) | |
| tree | bfe1aa77e018ab73e84ef5e0eeb560d4e4d05adc /arch/x86/boot | |
| parent | d28af26faa0b1daf3c692603d46bc4687c16f19e (diff) | |
| download | lwn-45b13b424faafb81c8c44541f093a682fdabdefc.tar.gz lwn-45b13b424faafb81c8c44541f093a682fdabdefc.zip | |
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 <kyle.d.pelton@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: dave.hansen@linux.intel.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Huang <wei@redhat.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190206115253.1907-1-kirill.shutemov@linux.intel.com
Diffstat (limited to 'arch/x86/boot')
| -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 */ |