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When ExitBootServices() invokes efi_shutdown_hook(), there may be nothing to generate an interrupt since the timer is disabled in the first step of ExitBootServices(). Additionally, for VMs OVMF masks everything from the PIC (except the timer) by default. This means that calling cpu_nap() may hang indefinitely. This was seen in practice in netfront_reset() when running in a VM on XenServer. Fix this by skipping the halt if an EFI shutdown is in progress. Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> Modified-by: Michael Brown <mcb30@ipxe.org> Signed-off-by: Michael Brown <mcb30@ipxe.org>
58 lines
1.8 KiB
C
58 lines
1.8 KiB
C
/*
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* Copyright (C) 2016 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <ipxe/nap.h>
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#include <ipxe/efi/efi.h>
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/** @file
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*
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* iPXE CPU sleeping API for EFI
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*
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*/
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/**
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* Sleep until next interrupt
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*
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*/
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static void efiarm_cpu_nap ( void ) {
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/*
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* I can't find any EFI API that allows us to put the CPU to
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* sleep. The CpuSleep() function is defined in CpuLib.h, but
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* isn't part of any exposed protocol so we have no way to
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* call it.
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*
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* The EFI shell doesn't seem to bother sleeping the CPU; it
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* just sits there idly burning power.
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*
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* If a shutdown is in progess, there may be nothing to
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* generate an interrupt since the timer is disabled in the
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* first step of ExitBootServices().
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*/
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if ( ! efi_shutdown_in_progress )
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__asm__ __volatile__ ( "wfi" );
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}
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PROVIDE_NAP ( efiarm, cpu_nap, efiarm_cpu_nap );
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