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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Dave Young <dyoung@redhat.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Matthew Garrett <mjg59@google.com>,
	Ben Dooks <ben.dooks@codethink.co.uk>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Jerry Snitselaar <jsnitsel@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Lukas Wunner <lukas@wunner.de>, Lyude Paul <lyude@redhat.com>,
	Octavian Purdila <octavian.purdila@intel.com>,
	Peter Jones <pjones@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Scott Talbert <swt@techie.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-efi@vger.kernel.org, linux-integrity@vger.kernel.org,
	Ingo Molnar <mingo@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 16/46] efi/x86: Do not clean dummy variable in kexec path
Date: Mon,  4 Nov 2019 22:44:47 +0100
Message-ID: <20191104211844.811293602@linuxfoundation.org> (raw)
In-Reply-To: <20191104211830.912265604@linuxfoundation.org>

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 ad285404ea7f5..4bc352fc08f19 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -859,9 +859,6 @@ 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
 }
 
-- 
2.20.1




      parent reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191104211830.912265604@linuxfoundation.org>
2019-11-04 21:44 ` [PATCH 4.4 15/46] efi/cper: Fix endianness of PCIe class code Greg Kroah-Hartman
2019-11-04 21:44 ` Greg Kroah-Hartman [this message]

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