linux-kernel - [PATCH v2 5/6] x86/sgx: Hook sgx_memory

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Date:   Mon, 19 Jul 2021 11:20:08 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...el.com>,
        Dave Hansen <dave.hansen@...el.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Tony Luck <tony.luck@...el.com>
Subject: [PATCH v2 5/6] 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.

Pull the call to acquire the mutex earlier so the SGX errors are also
protected.

Make set_mce_nospec() skip SGX pages when trying to adjust
the 1:1 map.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/include/asm/set_memory.h |  4 ++++
 include/linux/mm.h                | 15 +++++++++++++++
 mm/memory-failure.c               | 19 +++++++++++++------
 3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 43fa081a1adb..801af8f30c83 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -2,6 +2,7 @@
 #ifndef _ASM_X86_SET_MEMORY_H
 #define _ASM_X86_SET_MEMORY_H
 
+#include <linux/mm.h>
 #include <asm/page.h>
 #include <asm-generic/set_memory.h>
 
@@ -98,6 +99,9 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
 	unsigned long decoy_addr;
 	int rc;
 
+	/* SGX pages are not in the 1:1 map */
+	if (sgx_is_epc_page(pfn << PAGE_SHIFT))
+		return 0;
 	/*
 	 * We would like to just call:
 	 *      set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7ca22e6e694a..2ff599bcf8c2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3283,5 +3283,20 @@ 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);
+bool sgx_is_epc_page(u64 paddr);
+#else
+static inline int sgx_memory_failure(unsigned long pfn, int flags)
+{
+	return -ENXIO;
+}
+
+static inline bool sgx_is_epc_page(u64 paddr)
+{
+	return false;
+}
+#endif
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index eefd823deb67..3ce6b6aabf0f 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1626,21 +1626,28 @@ int memory_failure(unsigned long pfn, int flags)
 	if (!sysctl_memory_failure_recovery)
 		panic("Memory failure on page %lx", pfn);
 
+	mutex_lock(&mf_mutex);
+
 	p = pfn_to_online_page(pfn);
 	if (!p) {
+		res = sgx_memory_failure(pfn, flags);
+		if (res == 0)
+			goto unlock_mutex;
+
 		if (pfn_valid(pfn)) {
 			pgmap = get_dev_pagemap(pfn, NULL);
-			if (pgmap)
-				return memory_failure_dev_pagemap(pfn, flags,
-								  pgmap);
+			if (pgmap) {
+				res = memory_failure_dev_pagemap(pfn, flags,
+								 pgmap);
+				goto unlock_mutex;
+			}
 		}
 		pr_err("Memory failure: %#lx: memory outside kernel control\n",
 			pfn);
-		return -ENXIO;
+		res = -ENXIO;
+		goto unlock_mutex;
 	}
 
-	mutex_lock(&mf_mutex);
-
 try_again:
 	if (PageHuge(p)) {
 		res = memory_failure_hugetlb(pfn, flags);
-- 
2.29.2