Revert "x86: disable IOMMUs on kernel crash"

commit 8f9f55e8 upstream.

This effectively reverts commit 61d047be.

Disabling the IOMMU can potetially allow DMA transactions to
complete without being translated.  Leave it enabled, and allow
crash kernel to do the IOMMU reinitialization properly.

Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/kernel/crash.c

@@ -27,7 +27,6 @@
 #include <asm/cpu.h>
 #include <asm/reboot.h>
 #include <asm/virtext.h>
-#include <asm/iommu.h>
 
 
 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
@@ -104,10 +103,5 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
 #ifdef CONFIG_HPET_TIMER
 	hpet_disable();
 #endif
-
-#ifdef CONFIG_X86_64
-	pci_iommu_shutdown();
-#endif
-
 	crash_save_cpu(regs, safe_smp_processor_id());
 }