diff mbox series

[v33,09/21] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page()

Message ID 20200617220844.57423-10-jarkko.sakkinen@linux.intel.com (mailing list archive)
State Rejected
Headers show
Series Intel SGX foundations | expand

Commit Message

Jarkko Sakkinen June 17, 2020, 10:08 p.m. UTC 
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>
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 | 61 ++++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/sgx/sgx.h  |  3 ++
 2 files changed, 64 insertions(+)

Comments

Borislav Petkov June 25, 2020, 5:06 p.m. UTC | #1 
On Thu, Jun 18, 2020 at 01:08:31AM +0300, Jarkko Sakkinen wrote:
> 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>
> 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 | 61 ++++++++++++++++++++++++++++++++++
>  arch/x86/kernel/cpu/sgx/sgx.h  |  3 ++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index c5831e3db14a..b776d249289f 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -83,6 +83,67 @@ 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);

<---- newline here.

> +	return page;
> +}

Otherwise looks good; nice comments.

Thx.
Jarkko Sakkinen June 25, 2020, 8:55 p.m. UTC | #2 
On Thu, Jun 25, 2020 at 07:06:48PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:31AM +0300, Jarkko Sakkinen wrote:
> > 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>
> > 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 | 61 ++++++++++++++++++++++++++++++++++
> >  arch/x86/kernel/cpu/sgx/sgx.h  |  3 ++
> >  2 files changed, 64 insertions(+)
> > 
> > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> > index c5831e3db14a..b776d249289f 100644
> > --- a/arch/x86/kernel/cpu/sgx/main.c
> > +++ b/arch/x86/kernel/cpu/sgx/main.c
> > @@ -83,6 +83,67 @@ 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);
> 
> <---- newline here.
> 
> > +	return page;
> > +}
> 
> Otherwise looks good; nice comments.

Thanks!

> 
> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette

/Jarko
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index c5831e3db14a..b776d249289f 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -83,6 +83,67 @@  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 6508bfefd6d9..aae6bfb3bc8a 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -50,4 +50,7 @@  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 */