ACK: [Precise][SRU][PATCH 1/1] Revert "x86/ioapic: Add register level checks to detect bogus io-apic entries"

[Stefan Bader]

On 10.04.2012 15:35, leann.ogasawara at canonical.com wrote:
> From: Leann Ogasawara <leann.ogasawara at canonical.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/974982
> 
> This reverts commit 73d63d038ee9f769f5e5b46792d227fe20e442c5.
> 
> This patch results in a NULL pointer dereference which renders a system
> unbootable if attempting to boot in pvops mode.  We received this patch
> via upstream stable v3.2.14.  However, upstream discussion indicates
> this patch was not meant to be included in any v3.2.y upstream stable
> release.  Revert it.
> 
> http://www.mail-archive.com/stable@vger.kernel.org/msg04782.html
> 
> Signed-off-by: Leann Ogasawara <leann.ogasawara at canonical.com>
> ---
>  arch/x86/kernel/apic/io_apic.c |   40 ++++++++--------------------------------
>  1 files changed, 8 insertions(+), 32 deletions(-)
> 
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index a25e276..6d939d7 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -3963,36 +3963,18 @@ int mp_find_ioapic_pin(int ioapic, u32 gsi)
>  static __init int bad_ioapic(unsigned long address)
>  {
>  	if (nr_ioapics >= MAX_IO_APICS) {
> -		pr_warn("WARNING: Max # of I/O APICs (%d) exceeded (found %d), skipping\n",
> -			MAX_IO_APICS, nr_ioapics);
> +		printk(KERN_WARNING "WARNING: Max # of I/O APICs (%d) exceeded "
> +		       "(found %d), skipping\n", MAX_IO_APICS, nr_ioapics);
>  		return 1;
>  	}
>  	if (!address) {
> -		pr_warn("WARNING: Bogus (zero) I/O APIC address found in table, skipping!\n");
> +		printk(KERN_WARNING "WARNING: Bogus (zero) I/O APIC address"
> +		       " found in table, skipping!\n");
>  		return 1;
>  	}
>  	return 0;
>  }
>  
> -static __init int bad_ioapic_register(int idx)
> -{
> -	union IO_APIC_reg_00 reg_00;
> -	union IO_APIC_reg_01 reg_01;
> -	union IO_APIC_reg_02 reg_02;
> -
> -	reg_00.raw = io_apic_read(idx, 0);
> -	reg_01.raw = io_apic_read(idx, 1);
> -	reg_02.raw = io_apic_read(idx, 2);
> -
> -	if (reg_00.raw == -1 && reg_01.raw == -1 && reg_02.raw == -1) {
> -		pr_warn("I/O APIC 0x%x registers return all ones, skipping!\n",
> -			mpc_ioapic_addr(idx));
> -		return 1;
> -	}
> -
> -	return 0;
> -}
> -
>  void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
>  {
>  	int idx = 0;
> @@ -4009,12 +3991,6 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
>  	ioapics[idx].mp_config.apicaddr = address;
>  
>  	set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
> -
> -	if (bad_ioapic_register(idx)) {
> -		clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
> -		return;
> -	}
> -
>  	ioapics[idx].mp_config.apicid = io_apic_unique_id(id);
>  	ioapics[idx].mp_config.apicver = io_apic_get_version(idx);
>  
> @@ -4035,10 +4011,10 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
>  	if (gsi_cfg->gsi_end >= gsi_top)
>  		gsi_top = gsi_cfg->gsi_end + 1;
>  
> -	pr_info("IOAPIC[%d]: apic_id %d, version %d, address 0x%x, GSI %d-%d\n",
> -		idx, mpc_ioapic_id(idx),
> -		mpc_ioapic_ver(idx), mpc_ioapic_addr(idx),
> -		gsi_cfg->gsi_base, gsi_cfg->gsi_end);
> +	printk(KERN_INFO "IOAPIC[%d]: apic_id %d, version %d, address 0x%x, "
> +	       "GSI %d-%d\n", idx, mpc_ioapic_id(idx),
> +	       mpc_ioapic_ver(idx), mpc_ioapic_addr(idx),
> +	       gsi_cfg->gsi_base, gsi_cfg->gsi_end);
>  
>  	nr_ioapics++;
>  }

Likely needs to be working sooner than later. So ack for the revert.



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