From: Dave Young dyoung@redhat.com
[ Upstream commit 2ecb7402cfc7f22764e7bbc80790e66eadb20560 ]
kexec reboot fails randomly in UEFI based KVM guest. The firmware just resets 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 the 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 a dummy object.
Drop the efi_delete_dummy_variable so that kexec reboot can work.
Signed-off-by: Dave Young dyoung@redhat.com Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org Acked-by: Matthew Garrett mjg59@google.com Cc: Ben Dooks ben.dooks@codethink.co.uk Cc: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Cc: Jerry Snitselaar jsnitsel@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Lukas Wunner lukas@wunner.de Cc: Lyude Paul lyude@redhat.com Cc: Octavian Purdila octavian.purdila@intel.com Cc: Peter Jones pjones@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Scott Talbert swt@techie.net Cc: Thomas Gleixner tglx@linutronix.de Cc: linux-efi@vger.kernel.org Cc: linux-integrity@vger.kernel.org Link: https://lkml.kernel.org/r/20191002165904.8819-8-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/platform/efi/efi.c | 3 --- 1 file changed, 3 deletions(-)
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index a7189a3b4d70f..3304f61538a26 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -894,9 +894,6 @@ static void __init kexec_enter_virtual_mode(void)
if (efi_enabled(EFI_OLD_MEMMAP) && (__supported_pte_mask & _PAGE_NX)) runtime_code_page_mkexec(); - - /* clean DUMMY object */ - efi_delete_dummy_variable(); #endif }