linux-kernel - [RFC PATCH v2 03/10] x86/sgx: Save enclave pointer for VA page

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Message-Id: <20220315010300.10199-4-cathy.zhang@intel.com>
Date:   Tue, 15 Mar 2022 09:02:53 +0800
From:   Cathy Zhang <cathy.zhang@...el.com>
To:     linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     dave.hansen@...el.com, ashok.raj@...el.com, cathy.zhang@...el.com
Subject: [RFC PATCH v2 03/10] x86/sgx: Save enclave pointer for VA page

Tearing down all enclaves is required by SGX SVN update, which
involves running the ENCLS[EREMOVE] instruction on every EPC
page. This (tearing down all enclaves) should be coordinated
with any enclaves that may be in the process of existing and thus
already be running ENCLS[EREMOVE] as part of enclave release.

In support of this coordination, it is required to know which enclave
owns each in-use EPC page. It is already possible to locate the
owning enclave of SECS and regular pages but not for VA pages.

Save the enclave pointer for each VA page to support locating its
owning enclave.

Note: to track 2T EPC memory, this scheme of tracking will use
additional 8M memory.

Signed-off-by: Cathy Zhang <cathy.zhang@...el.com>
---
 arch/x86/kernel/cpu/sgx/encl.h  | 1 +
 arch/x86/kernel/cpu/sgx/ioctl.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index 1807a7f55065..e6f14c45ad49 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -77,6 +77,7 @@ struct sgx_va_page {
 	struct sgx_epc_page *epc_page;
 	DECLARE_BITMAP(slots, SGX_VA_SLOT_COUNT);
 	struct list_head list;
+	struct sgx_encl *encl;
 };

 struct sgx_backing {
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 9eb429aeb319..0f7b3e24fb94 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -30,6 +30,7 @@ struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl)
 		if (!va_page)
 			return ERR_PTR(-ENOMEM);

+		va_page->encl = encl;
 		va_page->epc_page = sgx_alloc_va_page(va_page);
 		if (IS_ERR(va_page->epc_page)) {
 			err = ERR_CAST(va_page->epc_page);
-- 
2.17.1