lkml.org 
[lkml]   [2020]   [Sep]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v38 09/24] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page()
Date
Add __sgx_alloc_epc_page(), which iterates through EPC sections and borrows
a page structure that is not used by anyone else. When a page is no longer
needed it must be released with sgx_free_epc_page(). This function
implicitly calls ENCLS[EREMOVE], which will return the page to the
uninitialized state (i.e. not required from caller part).

Acked-by: Jethro Beekman <jethro@fortanix.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
arch/x86/kernel/cpu/sgx/main.c | 62 ++++++++++++++++++++++++++++++++++
arch/x86/kernel/cpu/sgx/sgx.h | 3 ++
2 files changed, 65 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index c5831e3db14a..97c6895fb6c9 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -83,6 +83,68 @@ static bool __init sgx_page_reclaimer_init(void)
return true;
}

+static struct sgx_epc_page *__sgx_alloc_epc_page_from_section(struct sgx_epc_section *section)
+{
+ struct sgx_epc_page *page;
+
+ if (list_empty(&section->page_list))
+ return NULL;
+
+ page = list_first_entry(&section->page_list, struct sgx_epc_page, list);
+ list_del_init(&page->list);
+
+ return page;
+}
+
+/**
+ * __sgx_alloc_epc_page() - Allocate an EPC page
+ *
+ * Iterate through EPC sections and borrow a free EPC page to the caller. When a
+ * page is no longer needed it must be released with sgx_free_epc_page().
+ *
+ * Return:
+ * an EPC page,
+ * -errno on error
+ */
+struct sgx_epc_page *__sgx_alloc_epc_page(void)
+{
+ struct sgx_epc_section *section;
+ struct sgx_epc_page *page;
+ int i;
+
+ for (i = 0; i < sgx_nr_epc_sections; i++) {
+ section = &sgx_epc_sections[i];
+ spin_lock(&section->lock);
+ page = __sgx_alloc_epc_page_from_section(section);
+ spin_unlock(&section->lock);
+
+ if (page)
+ return page;
+ }
+
+ return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * sgx_free_epc_page() - Free an EPC page
+ * @page: an EPC page
+ *
+ * Call EREMOVE for an EPC page and insert it back to the list of free pages.
+ */
+void sgx_free_epc_page(struct sgx_epc_page *page)
+{
+ struct sgx_epc_section *section = sgx_get_epc_section(page);
+ int ret;
+
+ ret = __eremove(sgx_get_epc_addr(page));
+ if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret))
+ return;
+
+ spin_lock(&section->lock);
+ list_add_tail(&page->list, &section->page_list);
+ spin_unlock(&section->lock);
+}
+
static void __init sgx_free_epc_section(struct sgx_epc_section *section)
{
struct sgx_epc_page *page;
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index dff4f5f16d09..fce756c3434b 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -49,4 +49,7 @@ static inline void *sgx_get_epc_addr(struct sgx_epc_page *page)
return section->va + (page->desc & PAGE_MASK) - section->pa;
}

+struct sgx_epc_page *__sgx_alloc_epc_page(void);
+void sgx_free_epc_page(struct sgx_epc_page *page);
+
#endif /* _X86_SGX_H */
--
2.25.1
\
 
 \ /
  Last update: 2020-09-16 02:55    [W:0.239 / U:0.184 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site