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From: Dave Young <>
Subject: [PATCH] do not clean dummy variable in kexec path
Date: Mon, 5 Aug 2019 16:35:53 +0800	[thread overview]
Message-ID: <> (raw)

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 <>
 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))
-	/* clean DUMMY object */
-	efi_delete_dummy_variable();

             reply	other threads:[~2019-08-05  8:36 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-05  8:35 Dave Young [this message]
2019-08-05 15:55 ` Ard Biesheuvel
2019-08-06  2:41   ` Dave Young
2019-08-08  7:49   ` Dave Young
2019-08-05 17:09 ` Matthew Garrett
2019-08-06  2:44   ` Dave Young

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