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Message-Id: <20190731150813.26289-13-kirill.shutemov@linux.intel.com>
Date: Wed, 31 Jul 2019 18:07:26 +0300
From: "Kirill A. Shutemov" <kirill@...temov.name>
To: Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>,
Andy Lutomirski <luto@...capital.net>,
David Howells <dhowells@...hat.com>
Cc: Kees Cook <keescook@...omium.org>,
Dave Hansen <dave.hansen@...el.com>,
Kai Huang <kai.huang@...ux.intel.com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>,
Alison Schofield <alison.schofield@...el.com>,
linux-mm@...ck.org, kvm@...r.kernel.org, keyrings@...r.kernel.org,
linux-kernel@...r.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv2 12/59] x86/mm: Add a helper to retrieve KeyID for a page
page_ext allows to store additional per-page information without growing
main struct page. The additional space can be requested at boot time.
Store KeyID in bits 31:16 of extended page flags. These bits are unused.
page_keyid() returns zero until page_ext is ready. page_ext initializer
enables a static branch to indicate that page_keyid() can use page_ext.
The same static branch will gate MKTME readiness in general.
We don't yet set KeyID for the page. It will come in the following
patch that implements prep_encrypted_page(). All pages have KeyID-0 for
now.
page_keyid() will be used by KVM which can be built as a module. We need
to export mktme_enabled_key to be able to inline page_keyid().
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
arch/x86/include/asm/mktme.h | 26 ++++++++++++++++++++++++++
arch/x86/include/asm/page.h | 1 +
arch/x86/mm/mktme.c | 21 +++++++++++++++++++++
include/linux/mm.h | 2 +-
include/linux/page_ext.h | 11 ++++++++++-
mm/page_ext.c | 3 +++
6 files changed, 62 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h
index 42a3b1b44669..46041075f617 100644
--- a/arch/x86/include/asm/mktme.h
+++ b/arch/x86/include/asm/mktme.h
@@ -2,6 +2,8 @@
#define _ASM_X86_MKTME_H
#include <linux/types.h>
+#include <linux/page_ext.h>
+#include <linux/jump_label.h>
#ifdef CONFIG_X86_INTEL_MKTME
extern phys_addr_t __mktme_keyid_mask;
@@ -12,10 +14,34 @@ extern int __mktme_nr_keyids;
extern int mktme_nr_keyids(void);
extern unsigned int mktme_algs;
+DECLARE_STATIC_KEY_FALSE(mktme_enabled_key);
+static inline bool mktme_enabled(void)
+{
+ return static_branch_unlikely(&mktme_enabled_key);
+}
+
+extern struct page_ext_operations page_mktme_ops;
+
+#define page_keyid page_keyid
+static inline int page_keyid(const struct page *page)
+{
+ if (!mktme_enabled())
+ return 0;
+
+ return lookup_page_ext(page)->keyid;
+}
+
#else
#define mktme_keyid_mask() ((phys_addr_t)0)
#define mktme_nr_keyids() 0
#define mktme_keyid_shift() 0
+
+#define page_keyid(page) 0
+
+static inline bool mktme_enabled(void)
+{
+ return false;
+}
#endif
#endif
diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 7555b48803a8..39af59487d5f 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -19,6 +19,7 @@
struct page;
#include <linux/range.h>
+#include <asm/mktme.h>
extern struct range pfn_mapped[];
extern int nr_pfn_mapped;
diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c
index 755afc6935b5..48c2d4c97356 100644
--- a/arch/x86/mm/mktme.c
+++ b/arch/x86/mm/mktme.c
@@ -27,3 +27,24 @@ int mktme_nr_keyids(void)
}
unsigned int mktme_algs;
+
+DEFINE_STATIC_KEY_FALSE(mktme_enabled_key);
+EXPORT_SYMBOL_GPL(mktme_enabled_key);
+
+static bool need_page_mktme(void)
+{
+ /* Make sure keyid doesn't collide with extended page flags */
+ BUILD_BUG_ON(__NR_PAGE_EXT_FLAGS > 16);
+
+ return !!mktme_nr_keyids();
+}
+
+static void init_page_mktme(void)
+{
+ static_branch_enable(&mktme_enabled_key);
+}
+
+struct page_ext_operations page_mktme_ops = {
+ .need = need_page_mktme,
+ .init = init_page_mktme,
+};
diff --git a/include/linux/mm.h b/include/linux/mm.h
index af1a56ff6764..3f9640f388ac 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1645,7 +1645,7 @@ static inline int vma_keyid(struct vm_area_struct *vma)
#endif
#ifndef page_keyid
-static inline int page_keyid(struct page *page)
+static inline int page_keyid(const struct page *page)
{
return 0;
}
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 09592951725c..a9fa95ae9847 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -22,6 +22,7 @@ enum page_ext_flags {
PAGE_EXT_YOUNG,
PAGE_EXT_IDLE,
#endif
+ __NR_PAGE_EXT_FLAGS
};
/*
@@ -32,7 +33,15 @@ enum page_ext_flags {
* then the page_ext for pfn always exists.
*/
struct page_ext {
- unsigned long flags;
+ union {
+ unsigned long flags;
+#ifdef CONFIG_X86_INTEL_MKTME
+ struct {
+ unsigned short __pad;
+ unsigned short keyid;
+ };
+#endif
+ };
};
extern void pgdat_page_ext_init(struct pglist_data *pgdat);
diff --git a/mm/page_ext.c b/mm/page_ext.c
index 5f5769c7db3b..c52b77c13cd9 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -65,6 +65,9 @@ static struct page_ext_operations *page_ext_ops[] = {
#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
&page_idle_ops,
#endif
+#ifdef CONFIG_X86_INTEL_MKTME
+ &page_mktme_ops,
+#endif
};
static unsigned long total_usage;
--
2.21.0
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