linux-kernel - Re: [RFC PATCH v4 25/28] x86: Access the setup data through sysfs decrypted

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Date:   Fri, 17 Mar 2017 15:09:43 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Dave Young <dyoung@...hat.com>
CC:     <linux-arch@...r.kernel.org>, <linux-efi@...r.kernel.org>,
        <kvm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <kasan-dev@...glegroups.com>, <linux-mm@...ck.org>,
        <iommu@...ts.linux-foundation.org>, Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Larry Woodman <lwoodman@...hat.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [RFC PATCH v4 25/28] x86: Access the setup data through sysfs
 decrypted

On 3/8/2017 1:09 AM, Dave Young wrote:
> On 02/16/17 at 09:47am, Tom Lendacky wrote:
>> Use memremap() to map the setup data.  This will make the appropriate
>> decision as to whether a RAM remapping can be done or if a fallback to
>> ioremap_cache() is needed (similar to the setup data debugfs support).
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> ---
>>  arch/x86/kernel/ksysfs.c |   27 ++++++++++++++-------------
>>  1 file changed, 14 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/x86/kernel/ksysfs.c b/arch/x86/kernel/ksysfs.c
>> index 4afc67f..d653b3e 100644
>> --- a/arch/x86/kernel/ksysfs.c
>> +++ b/arch/x86/kernel/ksysfs.c
>> @@ -16,6 +16,7 @@
>>  #include <linux/stat.h>
>>  #include <linux/slab.h>
>>  #include <linux/mm.h>
>> +#include <linux/io.h>
>>
>>  #include <asm/io.h>
>>  #include <asm/setup.h>
>> @@ -79,12 +80,12 @@ static int get_setup_data_paddr(int nr, u64 *paddr)
>>  			*paddr = pa_data;
>>  			return 0;
>>  		}
>> -		data = ioremap_cache(pa_data, sizeof(*data));
>> +		data = memremap(pa_data, sizeof(*data), MEMREMAP_WB);
>>  		if (!data)
>>  			return -ENOMEM;
>>
>>  		pa_data = data->next;
>> -		iounmap(data);
>> +		memunmap(data);
>>  		i++;
>>  	}
>>  	return -EINVAL;
>> @@ -97,17 +98,17 @@ static int __init get_setup_data_size(int nr, size_t *size)
>>  	u64 pa_data = boot_params.hdr.setup_data;
>>
>>  	while (pa_data) {
>> -		data = ioremap_cache(pa_data, sizeof(*data));
>> +		data = memremap(pa_data, sizeof(*data), MEMREMAP_WB);
>>  		if (!data)
>>  			return -ENOMEM;
>>  		if (nr == i) {
>>  			*size = data->len;
>> -			iounmap(data);
>> +			memunmap(data);
>>  			return 0;
>>  		}
>>
>>  		pa_data = data->next;
>> -		iounmap(data);
>> +		memunmap(data);
>>  		i++;
>>  	}
>>  	return -EINVAL;
>> @@ -127,12 +128,12 @@ static ssize_t type_show(struct kobject *kobj,
>>  	ret = get_setup_data_paddr(nr, &paddr);
>>  	if (ret)
>>  		return ret;
>> -	data = ioremap_cache(paddr, sizeof(*data));
>> +	data = memremap(paddr, sizeof(*data), MEMREMAP_WB);
>>  	if (!data)
>>  		return -ENOMEM;
>>
>>  	ret = sprintf(buf, "0x%x\n", data->type);
>> -	iounmap(data);
>> +	memunmap(data);
>>  	return ret;
>>  }
>>
>> @@ -154,7 +155,7 @@ static ssize_t setup_data_data_read(struct file *fp,
>>  	ret = get_setup_data_paddr(nr, &paddr);
>>  	if (ret)
>>  		return ret;
>> -	data = ioremap_cache(paddr, sizeof(*data));
>> +	data = memremap(paddr, sizeof(*data), MEMREMAP_WB);
>>  	if (!data)
>>  		return -ENOMEM;
>>
>> @@ -170,15 +171,15 @@ static ssize_t setup_data_data_read(struct file *fp,
>>  		goto out;
>>
>>  	ret = count;
>> -	p = ioremap_cache(paddr + sizeof(*data), data->len);
>> +	p = memremap(paddr + sizeof(*data), data->len, MEMREMAP_WB);
>>  	if (!p) {
>>  		ret = -ENOMEM;
>>  		goto out;
>>  	}
>>  	memcpy(buf, p + off, count);
>> -	iounmap(p);
>> +	memunmap(p);
>>  out:
>> -	iounmap(data);
>> +	memunmap(data);
>>  	return ret;
>>  }
>>
>> @@ -250,13 +251,13 @@ static int __init get_setup_data_total_num(u64 pa_data, int *nr)
>>  	*nr = 0;
>>  	while (pa_data) {
>>  		*nr += 1;
>> -		data = ioremap_cache(pa_data, sizeof(*data));
>> +		data = memremap(pa_data, sizeof(*data), MEMREMAP_WB);
>>  		if (!data) {
>>  			ret = -ENOMEM;
>>  			goto out;
>>  		}
>>  		pa_data = data->next;
>> -		iounmap(data);
>> +		memunmap(data);
>>  	}
>>
>>  out:
>>
>
> It would be better that these cleanup patches are sent separately.

Bjorn suggested something along the same line so I've combined all the
changes from ioremap to memremap as a single pre-patch in the series.
I could send them separately if needed.

Thanks,
Tom

>
> Acked-by: Dave Young <dyoung@...hat.com>
>
> Thanks
> Dave
>