Attachment 310081 Details for Bug 452587 – Fix paranoia about using BIOS quickboot mechanism.

[patch] Fix paranoia about using BIOS quickboot mechanism.

bios_quickboot.patch (text/plain), 2.78 KB, created by Alok Kataria on 2008-06-23 22:05:41 UTC

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Creator: Alok Kataria

Created: 2008-06-23 22:05:41 UTC

Size: 2.78 KB

patch

obsolete

>VMware, Inc. is providing the following patch to you under the terms of the GPL
>version 2 and no later version. This patch is provided as is, with no
>warranties or support. VMware disclaims all liability in connection with
>the use/inability to use this patch. Any use of the attached is
>considered acceptance of the above.
>
>Author : Alok Kataria <akataria@vmware.com>
>Commit : 63d38198a0f57dca87e6cb79931c7bedbb7ab069
>
>The shutdown status flag set to "0xA", corresponds to "JMP double word
>request without INT init".
>    
>This JMP at reboot time is at an unintended location. And results in
>Triple faults in our case.
>Though this error at reboot can be safely ignored in a VM environment,
>am not sure what the effect would be on a physical system. May be it
>will result in a triple fault and an eventual hardware reset thus
>masking this BUG in the kernel.
>    
>This fix just makes sure that we reset that status flag after
>initialization is done.
>    
>Fix paranoia about using BIOS quickboot mechanism.
>  
>Make sure that we clear the "shutdown status flag" in the CMOS register
>after each CPU is brought up.  This fixes a problem where the "shutdown
>status flag" may remain set when a CPU is brought up after booting.
>
>Signed-off-by: Alok N Kataria <akataria@vmware.com>
>
>Index: linux-2.6.18-92/arch/x86_64/kernel/smpboot.c
>===================================================================
>--- linux-2.6.18-92.orig/arch/x86_64/kernel/smpboot.c	2008-05-20 17:10:27.000000000 -0700
>+++ linux-2.6.18-92/arch/x86_64/kernel/smpboot.c	2008-06-11 16:23:05.000000000 -0700
>@@ -762,6 +762,23 @@
> }
> 
> /*
>+ * Cleanup possible dangling ends...
>+ */
>+static __cpuinit void smp_cleanup_boot(void)
>+{
>+	/*
>+	 * Paranoid:  Set warm reset code and vector here back
>+	 * to default values.
>+	 */
>+	CMOS_WRITE(0, 0xf);
>+
>+	/*
>+	 * Reset trampoline flag
>+	 */
>+	*((volatile int *) phys_to_virt(0x467)) = 0;
>+}
>+
>+/*
>  * Boot one CPU.
>  */
> static int __cpuinit do_boot_cpu(int cpu, int apicid)
>@@ -916,6 +933,8 @@
> #endif
> 		}
> 	}
>+
>+	smp_cleanup_boot();
> 	if (boot_error) {
> 		cpu_clear(cpu, cpu_callout_map); /* was set here (do_boot_cpu()) */
> 		clear_bit(cpu, &cpu_initialized); /* was set by cpu_init() */
>@@ -934,23 +953,6 @@
> unsigned long cache_decay_ticks;
> 
> /*
>- * Cleanup possible dangling ends...
>- */
>-static __cpuinit void smp_cleanup_boot(void)
>-{
>-	/*
>-	 * Paranoid:  Set warm reset code and vector here back
>-	 * to default values.
>-	 */
>-	CMOS_WRITE(0, 0xf);
>-
>-	/*
>-	 * Reset trampoline flag
>-	 */
>-	*((volatile int *) phys_to_virt(0x467)) = 0;
>-}
>-
>-/*
>  * Fall back to non SMP mode after errors.
>  *
>  * RED-PEN audit/test this more. I bet there is more state messed up here.
>@@ -1174,8 +1176,6 @@
>  */
> void __init smp_cpus_done(unsigned int max_cpus)
> {
>-	smp_cleanup_boot();
>-
> #ifdef CONFIG_X86_IO_APIC
> 	setup_ioapic_dest();
> #endif

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Attachments on bug 452587: 310080 | 310081 | 310082