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Date: Fri, 17 Sep 2021 14:38:30 -0700
From: Tony Luck <tony.luck@...el.com>
To: Sean Christopherson <seanjc@...gle.com>,
Jarkko Sakkinen <jarkko@...nel.org>,
Dave Hansen <dave.hansen@...el.com>
Cc: Cathy Zhang <cathy.zhang@...el.com>, linux-sgx@...r.kernel.org,
x86@...nel.org, linux-kernel@...r.kernel.org,
Tony Luck <tony.luck@...el.com>
Subject: [PATCH v5 1/7] x86/sgx: Provide indication of life-cycle of EPC pages
SGX EPC pages go through the following life cycle:
DIRTY ---> FREE ---> IN-USE --\
^ |
\-----------------/
Recovery action for poison for a DIRTY or FREE page is simple. Just
make sure never to allocate the page. IN-USE pages need some extra
handling.
It would be good to use the sgx_epc_page->owner field as an indicator
of where an EPC page is currently in that cycle (owner != NULL means
the EPC page is IN-USE). But there is one caller, sgx_alloc_va_page(),
that calls with NULL.
Since there are multiple uses of the "owner" field with different types
change the sgx_epc_page structure to define an anonymous union with
each of the uses explicitly called out.
Start epc_pages out with a non-NULL owner while they are in DIRTY state.
Fix up the one holdout to provide a non-NULL owner.
Refactor the allocation sequence so that changes to/from NULL
value happen together with adding/removing the epc_page from
a free list while the node->lock is held.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
arch/x86/kernel/cpu/sgx/encl.c | 5 +++--
arch/x86/kernel/cpu/sgx/encl.h | 2 +-
arch/x86/kernel/cpu/sgx/ioctl.c | 2 +-
arch/x86/kernel/cpu/sgx/main.c | 23 ++++++++++++-----------
arch/x86/kernel/cpu/sgx/sgx.h | 12 ++++++++----
5 files changed, 25 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 001808e3901c..ad8c61933b0a 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -667,6 +667,7 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm,
/**
* sgx_alloc_va_page() - Allocate a Version Array (VA) page
+ * @va_page: struct sgx_va_page connected to this VA page
*
* Allocate a free EPC page and convert it to a Version Array (VA) page.
*
@@ -674,12 +675,12 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm,
* a VA page,
* -errno otherwise
*/
-struct sgx_epc_page *sgx_alloc_va_page(void)
+struct sgx_epc_page *sgx_alloc_va_page(struct sgx_va_page *va_page)
{
struct sgx_epc_page *epc_page;
int ret;
- epc_page = sgx_alloc_epc_page(NULL, true);
+ epc_page = sgx_alloc_epc_page(va_page, true);
if (IS_ERR(epc_page))
return ERR_CAST(epc_page);
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index fec43ca65065..3d12dbeae14a 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -111,7 +111,7 @@ void sgx_encl_put_backing(struct sgx_backing *backing, bool do_write);
int sgx_encl_test_and_clear_young(struct mm_struct *mm,
struct sgx_encl_page *page);
-struct sgx_epc_page *sgx_alloc_va_page(void);
+struct sgx_epc_page *sgx_alloc_va_page(struct sgx_va_page *va_page);
unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page);
void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset);
bool sgx_va_page_full(struct sgx_va_page *va_page);
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 83df20e3e633..655ce0bb069d 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -30,7 +30,7 @@ static struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl)
if (!va_page)
return ERR_PTR(-ENOMEM);
- va_page->epc_page = sgx_alloc_va_page();
+ va_page->epc_page = sgx_alloc_va_page(va_page);
if (IS_ERR(va_page->epc_page)) {
err = ERR_CAST(va_page->epc_page);
kfree(va_page);
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 63d3de02bbcc..4a5b51d16133 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -457,7 +457,7 @@ static bool __init sgx_page_reclaimer_init(void)
return true;
}
-static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
+static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(void *private, int nid)
{
struct sgx_numa_node *node = &sgx_numa_nodes[nid];
struct sgx_epc_page *page = NULL;
@@ -471,6 +471,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list);
list_del_init(&page->list);
+ page->private = private;
sgx_nr_free_pages--;
spin_unlock(&node->lock);
@@ -480,6 +481,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
/**
* __sgx_alloc_epc_page() - Allocate an EPC page
+ * @owner: the owner of the EPC page
*
* Iterate through NUMA nodes and reserve ia free EPC page to the caller. Start
* from the NUMA node, where the caller is executing.
@@ -488,14 +490,14 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
* - an EPC page: A borrowed EPC pages were available.
* - NULL: Out of EPC pages.
*/
-struct sgx_epc_page *__sgx_alloc_epc_page(void)
+struct sgx_epc_page *__sgx_alloc_epc_page(void *private)
{
struct sgx_epc_page *page;
int nid_of_current = numa_node_id();
int nid = nid_of_current;
if (node_isset(nid_of_current, sgx_numa_mask)) {
- page = __sgx_alloc_epc_page_from_node(nid_of_current);
+ page = __sgx_alloc_epc_page_from_node(private, nid_of_current);
if (page)
return page;
}
@@ -506,7 +508,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
if (nid == nid_of_current)
break;
- page = __sgx_alloc_epc_page_from_node(nid);
+ page = __sgx_alloc_epc_page_from_node(private, nid);
if (page)
return page;
}
@@ -559,7 +561,7 @@ int sgx_unmark_page_reclaimable(struct sgx_epc_page *page)
/**
* sgx_alloc_epc_page() - Allocate an EPC page
- * @owner: the owner of the EPC page
+ * @private: per-caller private data
* @reclaim: reclaim pages if necessary
*
* Iterate through EPC sections and borrow a free EPC page to the caller. When a
@@ -574,16 +576,14 @@ int sgx_unmark_page_reclaimable(struct sgx_epc_page *page)
* an EPC page,
* -errno on error
*/
-struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
+struct sgx_epc_page *sgx_alloc_epc_page(void *private, bool reclaim)
{
struct sgx_epc_page *page;
for ( ; ; ) {
- page = __sgx_alloc_epc_page();
- if (!IS_ERR(page)) {
- page->owner = owner;
+ page = __sgx_alloc_epc_page(private);
+ if (!IS_ERR(page))
break;
- }
if (list_empty(&sgx_active_page_list))
return ERR_PTR(-ENOMEM);
@@ -624,6 +624,7 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
spin_lock(&node->lock);
+ page->private = NULL;
list_add_tail(&page->list, &node->free_page_list);
sgx_nr_free_pages++;
@@ -652,7 +653,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
for (i = 0; i < nr_pages; i++) {
section->pages[i].section = index;
section->pages[i].flags = 0;
- section->pages[i].owner = NULL;
+ section->pages[i].private = "dirty";
list_add_tail(§ion->pages[i].list, &sgx_dirty_page_list);
}
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 4628acec0009..8b1be10a46f6 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -28,8 +28,12 @@
struct sgx_epc_page {
unsigned int section;
- unsigned int flags;
- struct sgx_encl_page *owner;
+ int flags;
+ union {
+ void *private;
+ struct sgx_encl_page *owner;
+ struct sgx_encl_page *vepc;
+ };
struct list_head list;
};
@@ -77,12 +81,12 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
return section->virt_addr + index * PAGE_SIZE;
}
-struct sgx_epc_page *__sgx_alloc_epc_page(void);
+struct sgx_epc_page *__sgx_alloc_epc_page(void *private);
void sgx_free_epc_page(struct sgx_epc_page *page);
void sgx_mark_page_reclaimable(struct sgx_epc_page *page);
int sgx_unmark_page_reclaimable(struct sgx_epc_page *page);
-struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim);
+struct sgx_epc_page *sgx_alloc_epc_page(void *private, bool reclaim);
#ifdef CONFIG_X86_SGX_KVM
int __init sgx_vepc_init(void);
--
2.31.1
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