Re: [RFC PATCH v4 24/28] x86: Access the setup data through debugfs decrypted

[Tom Lendacky]

On 3/8/2017 1:04 AM, Dave Young wrote:
> On 02/16/17 at 09:47am, Tom Lendacky wrote:
> > Use memremap() to map the setup data.  This simplifies the code and will
> > make the appropriate decision as to whether a RAM remapping can be done
> > or if a fallback to ioremap_cache() is needed (which includes checking
> > PageHighMem).
> >
> > Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > ---
> >  arch/x86/kernel/kdebugfs.c |   30 +++++++++++-------------------
> >  1 file changed, 11 insertions(+), 19 deletions(-)
> >
> > diff --git a/arch/x86/kernel/kdebugfs.c b/arch/x86/kernel/kdebugfs.c
> > index bdb83e4..c3d354d 100644
> > --- a/arch/x86/kernel/kdebugfs.c
> > +++ b/arch/x86/kernel/kdebugfs.c
> > @@ -48,17 +48,13 @@ static ssize_t setup_data_read(struct file *file, char __user *user_buf,
> >
> >  	pa = node->paddr + sizeof(struct setup_data) + pos;
> >  	pg = pfn_to_page((pa + count - 1) >> PAGE_SHIFT);
> > -	if (PageHighMem(pg)) {
> > -		p = ioremap_cache(pa, count);
> > -		if (!p)
> > -			return -ENXIO;
> > -	} else
> > -		p = __va(pa);
> > +	p = memremap(pa, count, MEMREMAP_WB);
> > +	if (!p)
> > +		return -ENXIO;
>
> -ENOMEM looks better for memremap, ditto for other places..

Makes sense, I'll change them.

Thanks,
Tom

> >  	remain = copy_to_user(user_buf, p, count);
> >
> > -	if (PageHighMem(pg))
> > -		iounmap(p);
> > +	memunmap(p);
> >
> >  	if (remain)
> >  		return -EFAULT;
> > @@ -127,15 +123,12 @@ static int __init create_setup_data_nodes(struct dentry *parent)
> >  		}
> >
> >  		pg = pfn_to_page((pa_data+sizeof(*data)-1) >> PAGE_SHIFT);
> > -		if (PageHighMem(pg)) {
> > -			data = ioremap_cache(pa_data, sizeof(*data));
> > -			if (!data) {
> > -				kfree(node);
> > -				error = -ENXIO;
> > -				goto err_dir;
> > -			}
> > -		} else
> > -			data = __va(pa_data);
> > +		data = memremap(pa_data, sizeof(*data), MEMREMAP_WB);
> > +		if (!data) {
> > +			kfree(node);
> > +			error = -ENXIO;
> > +			goto err_dir;
> > +		}
> >
> >  		node->paddr = pa_data;
> >  		node->type = data->type;
> > @@ -143,8 +136,7 @@ static int __init create_setup_data_nodes(struct dentry *parent)
> >  		error = create_setup_data_node(d, no, node);
> >  		pa_data = data->next;
> >
> > -		if (PageHighMem(pg))
> > -			iounmap(data);
> > +		memunmap(data);
> >  		if (error)
> >  			goto err_dir;
> >  		no++;
>
> Thanks
> Dave