linux-kernel - [RFC PATCH 3/4] x86/sgx: Hook sgx_memory

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Date:   Tue,  8 Jun 2021 14:40:37 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Dave Hansen <dave.hansen@...el.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Tony Luck <tony.luck@...el.com>
Subject: [RFC PATCH 3/4] x86/sgx: Hook sgx_memory_failure() into mainline code

Add a call inside memory_failure() to check if the address is an SGX
EPC page and handle it.

Note the SGX EPC pages do not have a "struct page" entry, so the hook
goes in at the same point as the device mapping hook.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 include/linux/mm.h  | 9 +++++++++
 mm/memory-failure.c | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c274f75efcf9..8ad4c513d4cc 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3248,5 +3248,14 @@ static inline int seal_check_future_write(int seals, struct vm_area_struct *vma)
 	return 0;
 }
 
+#ifdef CONFIG_X86_SGX
+int sgx_memory_failure(unsigned long pfn, int flags);
+#else
+static inline int sgx_memory_failure(unsigned long pfn, int flags)
+{
+	return -ENXIO;
+}
+#endif
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 85ad98c00fd9..c2ade18fd8d5 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1413,6 +1413,10 @@ int memory_failure(unsigned long pfn, int flags)
 
 	p = pfn_to_online_page(pfn);
 	if (!p) {
+		res = sgx_memory_failure(pfn, flags);
+		if (res == 0)
+			return 0;
+
 		if (pfn_valid(pfn)) {
 			pgmap = get_dev_pagemap(pfn, NULL);
 			if (pgmap)
-- 
2.29.2