Re: [PATCH 03/25] x86/sgx: Wipe out EREMOVE from sgx_free_epc_page()
From: Sean Christopherson <seanjc@google.com>
Date: 2021-03-01 22:13:44
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lkml
On Mon, Mar 01, 2021, Kai Huang wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 7449ef33f081..a7dc86e87a09 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c@@ -381,6 +381,26 @@ const struct vm_operations_struct sgx_vm_ops = { .access = sgx_vma_access, }; +static void sgx_encl_free_epc_page(struct sgx_epc_page *epc_page) +{ + int ret; + + WARN_ON_ONCE(epc_page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED); + + ret = __eremove(sgx_get_epc_virt_addr(epc_page)); + if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret)) {
This can be ENCLS_WARN, especially if you're printing a separate error message about leaking the page. That being said, I'm not sure a seperate error message is a good idea. If other stuff gets dumped to the kernel log between the WARN and the pr_err_once(), it may not be clear to admins that the two events are directly connected. It's even possible the prints could come from two different CPUs. Why not dump a short blurb in the WARN itself? The error message can be thrown in a define if the line length is too obnoxious (it's ~109 chars if embedded directly). #define EREMOVE_ERROR_MESSAGE \ "EREMOVE returned %d (0x%x). EPC page leaked, reboot recommended." if (WARN_ONCE(ret, EREMOVE_ERROR_MESSAGE, ret, ret))
+ /*
+ * Give a message to remind EPC page is leaked, and requires
+ * machine reboot to get leaked pages back. This can be improved
+ * in the future by adding stats of leaked pages, etc.
+ */
+ pr_err_once("EPC page is leaked. Require machine reboot to get leaked pages back.\n");
+ return;
+ }
+
+ sgx_free_epc_page(epc_page);
+}
+
/**
* sgx_encl_release - Destroy an enclave instance
* @kref: address of a kref inside &sgx_encl