linux-kernel - [RFC PATCH v3 18/20] x86: Access the setup data through debugfs un-encrypted

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Message-ID: <20161110003814.3280.56548.stgit@tlendack-t1.amdoffice.net>
Date:   Wed, 9 Nov 2016 18:38:15 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     <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>
CC:     Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        "Paolo Bonzini" <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        "Ingo Molnar" <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: [RFC PATCH v3 18/20] x86: Access the setup data through debugfs
 un-encrypted

Since the setup data is in memory in the clear, it must be accessed as
un-encrypted.  Always use ioremap (similar to sysfs setup data support)
to map the data.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 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..a58a82e 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 = ioremap_cache(pa, count);
+	if (!p)
+		return -ENXIO;
 
 	remain = copy_to_user(user_buf, p, count);
 
-	if (PageHighMem(pg))
-		iounmap(p);
+	iounmap(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 = ioremap_cache(pa_data, sizeof(*data));
+		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);
+		iounmap(data);
 		if (error)
 			goto err_dir;
 		no++;