linux-kernel - [PATCH 1/2] x86: sgx_vepc: extract sgx_vepc_remove

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Date:   Mon, 13 Sep 2021 09:11:52 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     x86@...nel.org, linux-sgx@...r.kernel.org, jarkko@...nel.org,
        dave.hansen@...ux.intel.com, yang.zhong@...el.com
Subject: [PATCH 1/2] x86: sgx_vepc: extract sgx_vepc_remove_page

Windows expects all pages to be in uninitialized state on startup.
In order to implement this, we will need a ioctl that performs
EREMOVE on all pages mapped by a /dev/sgx_vepc file descriptor:
other possibilities, such as closing and reopening the device,
are racy.

Start the implementation by pulling the EREMOVE into a separate
function.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kernel/cpu/sgx/virt.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
index 64511c4a5200..59b9c13121cd 100644
--- a/arch/x86/kernel/cpu/sgx/virt.c
+++ b/arch/x86/kernel/cpu/sgx/virt.c
@@ -111,7 +111,7 @@ static int sgx_vepc_mmap(struct file *file, struct vm_area_struct *vma)
 	return 0;
 }
 
-static int sgx_vepc_free_page(struct sgx_epc_page *epc_page)
+static int sgx_vepc_remove_page(struct sgx_epc_page *epc_page)
 {
 	int ret;
 
@@ -140,11 +140,17 @@ static int sgx_vepc_free_page(struct sgx_epc_page *epc_page)
 		 */
 		WARN_ONCE(ret != SGX_CHILD_PRESENT, EREMOVE_ERROR_MESSAGE,
 			  ret, ret);
-		return ret;
 	}
+	return ret;
+}
 
-	sgx_free_epc_page(epc_page);
+static int sgx_vepc_free_page(struct sgx_epc_page *epc_page)
+{
+	int ret = sgx_vepc_remove_page(epc_page);
+	if (ret)
+		return ret;
 
+	sgx_free_epc_page(epc_page);
 	return 0;
 }
 
-- 
2.27.0