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

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Date:   Wed, 8 Mar 2017 15:09:34 +0800
From:   Dave Young <dyoung@...hat.com>
To:     Tom Lendacky <thomas.lendacky@....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 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.

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

Thanks
Dave