linux-kernel - Re: [PATCH v4 20/28] x86, irq: More strict checking about registering ioapic

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Date:	Mon, 21 Oct 2013 18:54:44 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>, Tony Luck <tony.luck@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, <linux-pci@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
	Joerg Roedel <joro@...tes.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
	Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
Subject: Re: [PATCH v4 20/28] x86, irq: More strict checking about registering
 ioapic

>  int mp_find_ioapic_pin(int ioapic, u32 gsi)
>  {
>  	struct mp_ioapic_gsi *gsi_cfg;
> @@ -3888,6 +3894,11 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
>  	if (bad_ioapic(address))
>  		return;
>  
> +	/* already registered ? */
> +	idx = __mp_find_ioapic(gsi_base);
> +	if (idx >= 0)
> +		return;

Hi Yinghai,
   If you add whether ioapic was already registered check here, so we will fail to add ioapic into global ioapic_list.
Then we also can not hot remove this ioapic.


1. We will call mp_register_ioapic during analyze MADT first.
2. We will try to add hotplug ioapic(which contain _GSB) to ioapic_list in acpi_pci_ioapic_add(), but will found this
ioapic has been registered.

Thanks!
Yijing.


> +
>  	idx = find_first_zero_bit(ioapics_mask, MAX_IO_APICS);
>  	if (idx >= MAX_IO_APICS) {
>  		pr_warn("WARNING: Max # of I/O APICs (%d) exceeded, skipping\n",
> @@ -3914,6 +3925,13 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
>  	 * and to prevent reprogramming of IOAPIC pins (PCI GSIs).
>  	 */
>  	entries = io_apic_get_redir_entries(idx);
> +
> +	if (!entries || entries > MP_MAX_IOAPIC_PIN) {
> +		clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
> +		memset(&ioapics[idx], 0, sizeof(struct ioapic));
> +		return;
> +	}
> +
>  	gsi_cfg = mp_ioapic_gsi_routing(idx);
>  	gsi_cfg->gsi_base = gsi_base;
>  	gsi_cfg->gsi_end = gsi_base + entries - 1;
> 


-- 
Thanks!
Yijing

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