From: Tom Lendacky <thomas.lendacky@amd.com>
Subject: [RFC PATCH v3 18/20] x86: Access the setup data through debugfs
 un-encrypted
To: <linux-arch@vger.kernel.org>, <linux-efi@vger.kernel.org>,
        <kvm@vger.kernel.org>, <linux-doc@vger.kernel.org>, <x86@kernel.org>,
        <linux-kernel@vger.kernel.org>, <kasan-dev@googlegroups.com>,
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CC: Rik van Riel <riel@redhat.com>,
        Radim =?utf-8?b?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, Jonathan Corbet <corbet@lwn.net>,
        Matt Fleming <matt@codeblueprint.co.uk>,
        Joerg Roedel <joro@8bytes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        "Paolo Bonzini" <pbonzini@redhat.com>,
        Larry Woodman <lwoodman@redhat.com>, "Ingo Molnar" <mingo@redhat.com>,
        Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        Dmitry Vyukov <dvyukov@google.com>
Date: Wed, 9 Nov 2016 18:38:15 -0600
Message-ID: <20161110003814.3280.56548.stgit@tlendack-t1.amdoffice.net>
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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@amd.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++;