[PATCH] do not clean dummy variable in kexec path

From: Dave Young
Date: Mon Aug 05 2019 - 04:36:02 EST


kexec reboot fails randomly in UEFI based kvm guest. The firmware
just reset while calling efi_delete_dummy_variable(); Unfortunately
I don't know how to debug the firmware, it is also possible a potential
problem on real hardware as well although nobody reproduced it.

The intention of efi_delete_dummy_variable is to trigger garbage collection
when entering virtual mode. But SetVirtualAddressMap can only run once
for each physical reboot, thus kexec_enter_virtual_mode is not necessarily
a good place to clean dummy object.

Drop efi_delete_dummy_variable so that kexec reboot can work.

Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
---
arch/x86/platform/efi/efi.c | 3 ---
1 file changed, 3 deletions(-)

--- linux-x86.orig/arch/x86/platform/efi/efi.c
+++ linux-x86/arch/x86/platform/efi/efi.c
@@ -894,9 +894,6 @@ static void __init kexec_enter_virtual_m

if (efi_enabled(EFI_OLD_MEMMAP) && (__supported_pte_mask & _PAGE_NX))
runtime_code_page_mkexec();
-
- /* clean DUMMY object */
- efi_delete_dummy_variable();
#endif
}