From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Andrew Morton <akpm@linux-foundation.org>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@amacapital.net>,
David Howells <dhowells@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
Dave Hansen <dave.hansen@intel.com>,
Kai Huang <kai.huang@linux.intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Alison Schofield <alison.schofield@intel.com>,
linux-mm@kvack.org, kvm@vger.kernel.org,
keyrings@vger.kernel.org, linux-kernel@vger.kernel.org,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCHv2 45/59] x86/mm: Keep reference counts on hardware key usage for MKTME
Date: Wed, 31 Jul 2019 18:07:59 +0300 [thread overview]
Message-ID: <20190731150813.26289-46-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <20190731150813.26289-1-kirill.shutemov@linux.intel.com>
From: Alison Schofield <alison.schofield@intel.com>
The MKTME (Multi-Key Total Memory Encryption) Key Service needs
a reference count the key usage. This reference count is used
to determine when a hardware encryption KeyID is no longer in use
and can be freed and reassigned to another Userspace Key.
The MKTME Key service does the percpu_ref_init and _kill.
Encrypted VMA's and encrypted pages are included in the reference
counts per keyid.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/include/asm/mktme.h | 5 +++++
arch/x86/mm/mktme.c | 37 ++++++++++++++++++++++++++++++++++--
include/linux/mm.h | 2 ++
kernel/fork.c | 2 ++
4 files changed, 44 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h
index e8f7f80bb013..a5f664d3805b 100644
--- a/arch/x86/include/asm/mktme.h
+++ b/arch/x86/include/asm/mktme.h
@@ -20,6 +20,11 @@ extern unsigned int mktme_algs;
extern void mprotect_set_encrypt(struct vm_area_struct *vma, int newkeyid,
unsigned long start, unsigned long end);
+/* MTKME encrypt_count for VMAs */
+extern struct percpu_ref *encrypt_count;
+extern void vma_get_encrypt_ref(struct vm_area_struct *vma);
+extern void vma_put_encrypt_ref(struct vm_area_struct *vma);
+
DECLARE_STATIC_KEY_FALSE(mktme_enabled_key);
static inline bool mktme_enabled(void)
{
diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c
index 05bbf5058ade..17366d81c21b 100644
--- a/arch/x86/mm/mktme.c
+++ b/arch/x86/mm/mktme.c
@@ -84,11 +84,12 @@ void mprotect_set_encrypt(struct vm_area_struct *vma, int newkeyid,
if (oldkeyid == newkeyid)
return;
-
+ vma_put_encrypt_ref(vma);
newprot = pgprot_val(vma->vm_page_prot);
newprot &= ~mktme_keyid_mask();
newprot |= (unsigned long)newkeyid << mktme_keyid_shift();
vma->vm_page_prot = __pgprot(newprot);
+ vma_get_encrypt_ref(vma);
/*
* The VMA doesn't have any inherited pages.
@@ -97,6 +98,18 @@ void mprotect_set_encrypt(struct vm_area_struct *vma, int newkeyid,
unlink_anon_vmas(vma);
}
+void vma_get_encrypt_ref(struct vm_area_struct *vma)
+{
+ if (vma_keyid(vma))
+ percpu_ref_get(&encrypt_count[vma_keyid(vma)]);
+}
+
+void vma_put_encrypt_ref(struct vm_area_struct *vma)
+{
+ if (vma_keyid(vma))
+ percpu_ref_put(&encrypt_count[vma_keyid(vma)]);
+}
+
/* Prepare page to be used for encryption. Called from page allocator. */
void __prep_encrypted_page(struct page *page, int order, int keyid, bool zero)
{
@@ -137,6 +150,22 @@ void __prep_encrypted_page(struct page *page, int order, int keyid, bool zero)
page++;
}
+
+ /*
+ * Make sure the KeyID cannot be freed until the last page that
+ * uses the KeyID is gone.
+ *
+ * This is required because the page may live longer than VMA it
+ * is mapped into (i.e. in get_user_pages() case) and having
+ * refcounting per-VMA is not enough.
+ *
+ * Taking a reference per-4K helps in case if the page will be
+ * split after the allocation. free_encrypted_page() will balance
+ * out the refcount even if the page was split and freed as bunch
+ * of 4K pages.
+ */
+
+ percpu_ref_get_many(&encrypt_count[keyid], 1 << order);
}
/*
@@ -145,7 +174,9 @@ void __prep_encrypted_page(struct page *page, int order, int keyid, bool zero)
*/
void free_encrypted_page(struct page *page, int order)
{
- int i;
+ int i, keyid;
+
+ keyid = page_keyid(page);
/*
* The hardware/CPU does not enforce coherency between mappings
@@ -177,6 +208,8 @@ void free_encrypted_page(struct page *page, int order)
lookup_page_ext(page)->keyid = 0;
page++;
}
+
+ percpu_ref_put_many(&encrypt_count[keyid], 1 << order);
}
static int sync_direct_mapping_pte(unsigned long keyid,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8551b5ebdedf..be27cb0cc0c7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2911,6 +2911,8 @@ static inline void mprotect_set_encrypt(struct vm_area_struct *vma,
int newkeyid,
unsigned long start,
unsigned long end) {}
+static inline void vma_get_encrypt_ref(struct vm_area_struct *vma) {}
+static inline void vma_put_encrypt_ref(struct vm_area_struct *vma) {}
#endif /* CONFIG_X86_INTEL_MKTME */
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index d8ae0f1b4148..00735092d370 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -349,12 +349,14 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
if (new) {
*new = *orig;
INIT_LIST_HEAD(&new->anon_vma_chain);
+ vma_get_encrypt_ref(new);
}
return new;
}
void vm_area_free(struct vm_area_struct *vma)
{
+ vma_put_encrypt_ref(vma);
kmem_cache_free(vm_area_cachep, vma);
}
--
2.21.0
next prev parent reply other threads:[~2019-07-31 15:24 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 15:07 [PATCHv2 00/59] Intel MKTME enabling Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 01/59] mm: Do no merge VMAs with different encryption KeyIDs Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 02/59] mm: Add helpers to setup zero page mappings Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 03/59] mm/ksm: Do not merge pages with different KeyIDs Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 04/59] mm/page_alloc: Unify alloc_hugepage_vma() Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 05/59] mm/page_alloc: Handle allocation for encrypted memory Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 06/59] mm/khugepaged: Handle encrypted pages Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 07/59] x86/mm: Mask out KeyID bits from page table entry pfn Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 08/59] x86/mm: Introduce helpers to read number, shift and mask of KeyIDs Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 09/59] x86/mm: Store bitmask of the encryption algorithms supported by MKTME Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 10/59] x86/mm: Preserve KeyID on pte_modify() and pgprot_modify() Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 11/59] x86/mm: Detect MKTME early Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 12/59] x86/mm: Add a helper to retrieve KeyID for a page Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 13/59] x86/mm: Add a helper to retrieve KeyID for a VMA Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 14/59] x86/mm: Add hooks to allocate and free encrypted pages Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 15/59] x86/mm: Map zero pages into encrypted mappings correctly Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 16/59] x86/mm: Rename CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 17/59] x86/mm: Allow to disable MKTME after enumeration Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 18/59] x86/mm: Calculate direct mapping size Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 19/59] x86/mm: Implement syncing per-KeyID direct mappings Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 20/59] x86/mm: Handle encrypted memory in page_to_virt() and __pa() Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 21/59] mm/page_ext: Export lookup_page_ext() symbol Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 22/59] mm/rmap: Clear vma->anon_vma on unlink_anon_vmas() Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 23/59] x86/pconfig: Set an activated algorithm in all MKTME commands Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 24/59] keys/mktme: Introduce a Kernel Key Service for MKTME Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 25/59] keys/mktme: Preparse the MKTME key payload Kirill A. Shutemov
2019-08-05 11:58 ` Ben Boeckel
2019-08-05 20:31 ` Alison Schofield
2019-08-13 13:06 ` Ben Boeckel
2019-07-31 15:07 ` [PATCHv2 26/59] keys/mktme: Instantiate MKTME keys Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 27/59] keys/mktme: Destroy " Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 28/59] keys/mktme: Move the MKTME payload into a cache aligned structure Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 29/59] keys/mktme: Set up PCONFIG programming targets for MKTME keys Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 30/59] keys/mktme: Program MKTME keys into the platform hardware Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 31/59] keys/mktme: Set up a percpu_ref_count for MKTME keys Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 32/59] keys/mktme: Clear the key programming from the MKTME hardware Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 33/59] keys/mktme: Require CAP_SYS_RESOURCE capability for MKTME keys Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 34/59] acpi: Remove __init from acpi table parsing functions Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 35/59] acpi/hmat: Determine existence of an ACPI HMAT Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 36/59] keys/mktme: Require ACPI HMAT to register the MKTME Key Service Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 37/59] acpi/hmat: Evaluate topology presented in ACPI HMAT for MKTME Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 38/59] keys/mktme: Do not allow key creation in unsafe topologies Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 39/59] keys/mktme: Support CPU hotplug for MKTME key service Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 40/59] keys/mktme: Block memory hotplug additions when MKTME is enabled Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 41/59] mm: Generalize the mprotect implementation to support extensions Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 42/59] syscall/x86: Wire up a system call for MKTME encryption keys Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 43/59] x86/mm: Set KeyIDs in encrypted VMAs for MKTME Kirill A. Shutemov
2019-07-31 15:07 ` [PATCHv2 44/59] mm: Add the encrypt_mprotect() system call " Kirill A. Shutemov
2019-07-31 15:07 ` Kirill A. Shutemov [this message]
2019-07-31 15:08 ` [PATCHv2 46/59] mm: Restrict MKTME memory encryption to anonymous VMAs Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 47/59] kvm, x86, mmu: setup MKTME keyID to spte for given PFN Kirill A. Shutemov
2019-08-06 20:26 ` Lendacky, Thomas
2019-08-07 14:28 ` Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 48/59] iommu/vt-d: Support MKTME in DMA remapping Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 49/59] x86/mm: introduce common code for mem encryption Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 50/59] x86/mm: Use common code for DMA memory encryption Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 51/59] x86/mm: Disable MKTME on incompatible platform configurations Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 52/59] x86/mm: Disable MKTME if not all system memory supports encryption Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 53/59] x86: Introduce CONFIG_X86_INTEL_MKTME Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 54/59] x86/mktme: Overview of Multi-Key Total Memory Encryption Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 55/59] x86/mktme: Document the MKTME provided security mitigations Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 56/59] x86/mktme: Document the MKTME kernel configuration requirements Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 57/59] x86/mktme: Document the MKTME Key Service API Kirill A. Shutemov
2019-08-05 11:58 ` Ben Boeckel
2019-08-05 20:44 ` Alison Schofield
2019-08-13 13:07 ` Ben Boeckel
2019-07-31 15:08 ` [PATCHv2 58/59] x86/mktme: Document the MKTME API for anonymous memory encryption Kirill A. Shutemov
2019-07-31 15:08 ` [PATCHv2 59/59] x86/mktme: Demonstration program using the MKTME APIs Kirill A. Shutemov
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