linux-kernel - [PATCHv2 13/59] x86/mm: Add a helper to retrieve KeyID for a VMA

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Date:   Wed, 31 Jul 2019 18:07:27 +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 13/59] x86/mm: Add a helper to retrieve KeyID for a VMA

We store KeyID in upper bits for vm_page_prot that match position of
KeyID in PTE. vma_keyid() extracts KeyID from vm_page_prot.

With KeyID in vm_page_prot we don't need to modify any page table helper
to propagate the KeyID to page table entires.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 arch/x86/include/asm/mktme.h | 12 ++++++++++++
 arch/x86/mm/mktme.c          |  7 +++++++
 2 files changed, 19 insertions(+)

diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h
index 46041075f617..52b115b30a42 100644
--- a/arch/x86/include/asm/mktme.h
+++ b/arch/x86/include/asm/mktme.h
@@ -5,6 +5,8 @@
 #include <linux/page_ext.h>
 #include <linux/jump_label.h>
 
+struct vm_area_struct;
+
 #ifdef CONFIG_X86_INTEL_MKTME
 extern phys_addr_t __mktme_keyid_mask;
 extern phys_addr_t mktme_keyid_mask(void);
@@ -31,6 +33,16 @@ static inline int page_keyid(const struct page *page)
 	return lookup_page_ext(page)->keyid;
 }
 
+#define vma_keyid vma_keyid
+int __vma_keyid(struct vm_area_struct *vma);
+static inline int vma_keyid(struct vm_area_struct *vma)
+{
+	if (!mktme_enabled())
+		return 0;
+
+	return __vma_keyid(vma);
+}
+
 #else
 #define mktme_keyid_mask()	((phys_addr_t)0)
 #define mktme_nr_keyids()	0
diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c
index 48c2d4c97356..d02867212e33 100644
--- a/arch/x86/mm/mktme.c
+++ b/arch/x86/mm/mktme.c
@@ -1,3 +1,4 @@
+#include <linux/mm.h>
 #include <asm/mktme.h>
 
 /* Mask to extract KeyID from physical address. */
@@ -48,3 +49,9 @@ struct page_ext_operations page_mktme_ops = {
 	.need = need_page_mktme,
 	.init = init_page_mktme,
 };
+
+int __vma_keyid(struct vm_area_struct *vma)
+{
+	pgprotval_t prot = pgprot_val(vma->vm_page_prot);
+	return (prot & mktme_keyid_mask()) >> mktme_keyid_shift();
+}
-- 
2.21.0