linux-kernel - Re: [PATCH v5 5/8] iommu/amd: copy old trans table from old kernel

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Message-ID: <20160921101807.GB13350@x1.redhat.com>
Date:   Wed, 21 Sep 2016 18:18:07 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, dyoung@...hat.com, xlpang@...hat.com,
        Vincent.Wan@....com
Subject: Re: [PATCH v5 5/8] iommu/amd: copy old trans table from old kernel

On 09/20/16 at 02:40pm, Joerg Roedel wrote:
> On Thu, Sep 15, 2016 at 11:03:23PM +0800, Baoquan He wrote:
> > Here several things need be done:
> > 1) If iommu is pre-enabled in a normal kernel, just disable it and print
> >    warning.
> > 2) If failed to copy dev table of old kernel, continue to proceed as
> >    it does in normal kernel.
> > 3) Re-enable event/cmd buffer and install the new DTE table to reg.
> > 4) Flush all caches
> > 
> > Signed-off-by: Baoquan He <bhe@...hat.com>
> > ---
> >  drivers/iommu/amd_iommu_init.c | 44 +++++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 41 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
> > index ce49641..47a8fc9 100644
> > --- a/drivers/iommu/amd_iommu_init.c
> > +++ b/drivers/iommu/amd_iommu_init.c
> > @@ -34,7 +34,7 @@
> >  #include <asm/iommu_table.h>
> >  #include <asm/io_apic.h>
> >  #include <asm/irq_remapping.h>
> > -
> > +#include <linux/crash_dump.h>
> 
> Please keep that empty line, it is there for readability.

Thanks, will change.

> 
> >  #include "amd_iommu_proto.h"
> >  #include "amd_iommu_types.h"
> >  #include "irq_remapping.h"
> > @@ -1344,6 +1344,12 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
> >  	iommu->int_enabled = false;
> >  
> >  	init_translation_status(iommu);
> > +	if (translation_pre_enabled(iommu) && !is_kdump_kernel()) {
> > +		iommu_disable(iommu);
> > +		clear_translation_pre_enabled(iommu);
> > +		pr_warn("Translation was enabled for IOMMU:%d but we are not in kdump mode\n",
> > +			iommu->index);
> > +	}
> >  
> >  	if (translation_pre_enabled(iommu))
> >  		pr_warn("Translation is already enabled - trying to copy translation structures\n");
> > @@ -1946,9 +1952,41 @@ static void early_enable_iommu(struct amd_iommu *iommu)
> >  static void early_enable_iommus(void)
> >  {
> >  	struct amd_iommu *iommu;
> > +	bool is_pre_enabled=false;
> >  
> > -	for_each_iommu(iommu)
> > -		early_enable_iommu(iommu);
> > +	for_each_iommu(iommu) {
> > +		if ( translation_pre_enabled(iommu) ) {
> 
> Coding style, too many spaces. There is more of that below.

Will change.

> 
> > +			is_pre_enabled = true;
> > +			break;
> > +		}
> > +	}
> > +
> > +	if ( !is_pre_enabled) {
> > +		for_each_iommu(iommu)
> > +			early_enable_iommu(iommu);
> > +	} else {
> > +		if (copy_dev_tables()) {
> > +			pr_err("Failed to copy DEV table from previous kernel.\n");
> > +			/*
> > +			 * If failed to copy dev tables from old kernel, continue to proceed
> > +			 * as it does in normal kernel.
> > +			 */
> > +			for_each_iommu(iommu) {
> > +				clear_translation_pre_enabled(iommu);
> > +				early_enable_iommu(iommu);
> > +			}
> > +		} else {
> > +			pr_info("Copied DEV table from previous kernel.\n");
> > +			for_each_iommu(iommu) {
> > +				iommu_feature_disable(iommu, CONTROL_CMDBUF_EN);
> > +		                iommu_feature_disable(iommu, CONTROL_EVT_LOG_EN);
> 
> Could you move that into new helpers (iommu_disable_command_buffer...)?

Yes, sure, will do.

> 
> > +		                iommu_enable_command_buffer(iommu);
> > +		                iommu_enable_event_buffer(iommu);
> > +		                iommu_set_device_table(iommu);
> > +		                iommu_flush_all_caches(iommu);
> > +			}
> > +		}
> > +	}
> >  }
> >  
> >  static void enable_iommus_v2(void)
> > -- 
> > 2.5.5
> >