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From: Joerg Roedel <joro@8bytes.org>
To: Takao Indoh <indou.takao@jp.fujitsu.com>
Cc: bhe@redhat.com, kexec@lists.infradead.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	alex.williamson@redhat.com, dwmw2@infradead.org
Subject: Re: [PATCH v2] intel-iommu: Quiesce devices before disabling IOMMU
Date: Tue, 24 Sep 2013 15:16:23 +0200	[thread overview]
Message-ID: <20130924131621.GC5150@8bytes.org> (raw)
In-Reply-To: <1379484541-4496-1-git-send-email-indou.takao@jp.fujitsu.com>

On Wed, Sep 18, 2013 at 03:09:01PM +0900, Takao Indoh wrote:
> +	/*
> +	 *  In the case of kdump, ioremap is needed because root-entry table
> +	 *  exists in first kernel's memory area which is not mapped in second
> +	 *  kernel
> +	 */
> +	root = (struct root_entry *)ioremap(addr, PAGE_SIZE);
> +	if (!root)
> +		return;
> +
> +	for (bus = 0; bus < ROOT_ENTRY_NR; bus++) {
> +		if (!root_present(&root[bus]))
> +			continue;
> +
> +		context = (struct context_entry *)ioremap(
> +			root[bus].val & VTD_PAGE_MASK, PAGE_SIZE);
> +		if (!context)
> +			continue;
> +
> +		for (devfn = 0; devfn < CONTEXT_ENTRY_NR; devfn++) {
> +			if (!context_present(&context[devfn]))
> +				continue;
> +
> +			dev = pci_get_domain_bus_and_slot(segment, bus, devfn);
> +			if (!dev)
> +				continue;
> +
> +			if (!pci_reset_bus(dev->bus)) /* go to next bus */
> +				break;
> +			else /* Try per-function reset */
> +				pci_reset_function(dev);
> +
> +		}
> +		iounmap(context);
> +	}
> +	iounmap(root);

I am not convinced that this is the right approach. If a device wasn't
translated by VT-d in the old kernel doesn't mean it will not be
translated in the new kernel. How about unconditionally resetting all
PCI busses and/or functions here before IOMMU initialization proceeds?


	Joerg



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WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Takao Indoh <indou.takao-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
Cc: bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org
Subject: Re: [PATCH v2] intel-iommu: Quiesce devices before disabling IOMMU
Date: Tue, 24 Sep 2013 15:16:23 +0200	[thread overview]
Message-ID: <20130924131621.GC5150@8bytes.org> (raw)
In-Reply-To: <1379484541-4496-1-git-send-email-indou.takao-+CUm20s59erQFUHtdCDX3A@public.gmane.org>

On Wed, Sep 18, 2013 at 03:09:01PM +0900, Takao Indoh wrote:
> +	/*
> +	 *  In the case of kdump, ioremap is needed because root-entry table
> +	 *  exists in first kernel's memory area which is not mapped in second
> +	 *  kernel
> +	 */
> +	root = (struct root_entry *)ioremap(addr, PAGE_SIZE);
> +	if (!root)
> +		return;
> +
> +	for (bus = 0; bus < ROOT_ENTRY_NR; bus++) {
> +		if (!root_present(&root[bus]))
> +			continue;
> +
> +		context = (struct context_entry *)ioremap(
> +			root[bus].val & VTD_PAGE_MASK, PAGE_SIZE);
> +		if (!context)
> +			continue;
> +
> +		for (devfn = 0; devfn < CONTEXT_ENTRY_NR; devfn++) {
> +			if (!context_present(&context[devfn]))
> +				continue;
> +
> +			dev = pci_get_domain_bus_and_slot(segment, bus, devfn);
> +			if (!dev)
> +				continue;
> +
> +			if (!pci_reset_bus(dev->bus)) /* go to next bus */
> +				break;
> +			else /* Try per-function reset */
> +				pci_reset_function(dev);
> +
> +		}
> +		iounmap(context);
> +	}
> +	iounmap(root);

I am not convinced that this is the right approach. If a device wasn't
translated by VT-d in the old kernel doesn't mean it will not be
translated in the new kernel. How about unconditionally resetting all
PCI busses and/or functions here before IOMMU initialization proceeds?


	Joerg

WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Takao Indoh <indou.takao@jp.fujitsu.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	dwmw2@infradead.org, kexec@lists.infradead.org,
	alex.williamson@redhat.com, bhe@redhat.com
Subject: Re: [PATCH v2] intel-iommu: Quiesce devices before disabling IOMMU
Date: Tue, 24 Sep 2013 15:16:23 +0200	[thread overview]
Message-ID: <20130924131621.GC5150@8bytes.org> (raw)
In-Reply-To: <1379484541-4496-1-git-send-email-indou.takao@jp.fujitsu.com>

On Wed, Sep 18, 2013 at 03:09:01PM +0900, Takao Indoh wrote:
> +	/*
> +	 *  In the case of kdump, ioremap is needed because root-entry table
> +	 *  exists in first kernel's memory area which is not mapped in second
> +	 *  kernel
> +	 */
> +	root = (struct root_entry *)ioremap(addr, PAGE_SIZE);
> +	if (!root)
> +		return;
> +
> +	for (bus = 0; bus < ROOT_ENTRY_NR; bus++) {
> +		if (!root_present(&root[bus]))
> +			continue;
> +
> +		context = (struct context_entry *)ioremap(
> +			root[bus].val & VTD_PAGE_MASK, PAGE_SIZE);
> +		if (!context)
> +			continue;
> +
> +		for (devfn = 0; devfn < CONTEXT_ENTRY_NR; devfn++) {
> +			if (!context_present(&context[devfn]))
> +				continue;
> +
> +			dev = pci_get_domain_bus_and_slot(segment, bus, devfn);
> +			if (!dev)
> +				continue;
> +
> +			if (!pci_reset_bus(dev->bus)) /* go to next bus */
> +				break;
> +			else /* Try per-function reset */
> +				pci_reset_function(dev);
> +
> +		}
> +		iounmap(context);
> +	}
> +	iounmap(root);

I am not convinced that this is the right approach. If a device wasn't
translated by VT-d in the old kernel doesn't mean it will not be
translated in the new kernel. How about unconditionally resetting all
PCI busses and/or functions here before IOMMU initialization proceeds?


	Joerg



  parent reply	other threads:[~2013-09-24 13:16 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-18  6:09 [PATCH v2] intel-iommu: Quiesce devices before disabling IOMMU Takao Indoh
2013-09-18  6:09 ` Takao Indoh
2013-09-18  6:09 ` Takao Indoh
2013-09-18  9:03 ` Baoquan He
2013-09-18  9:03   ` Baoquan He
2013-09-18  9:03   ` Baoquan He
2013-09-24 13:16 ` Joerg Roedel [this message]
2013-09-24 13:16   ` Joerg Roedel
2013-09-24 13:16   ` Joerg Roedel
2013-09-24 13:39   ` David Woodhouse
2013-09-24 13:39     ` David Woodhouse
2013-09-24 13:39     ` David Woodhouse

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