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Subject: [PATCH v10 2/7] x86/mce: relocate set{clear}_mce_nospec() functions
From:   Dan Williams <dan.j.williams@intel.com>
To:     linux-kernel@vger.kernel.org
Cc:     Christoph Hellwig <hch@lst.de>, Jane Chu <jane.chu@oracle.com>,
        Borislav Petkov <bp@suse.de>, x86@kernel.org,
        nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org
Date:   Fri, 13 May 2022 14:41:18 -0700
Message-ID: <165247798860.4117683.4554602198740624216.stgit@dwillia2-desk3.amr.corp.intel.com>
In-Reply-To: <20220422224508.440670-3-jane.chu@oracle.com>
References: <20220422224508.440670-3-jane.chu@oracle.com>
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From: Jane Chu <jane.chu@oracle.com>

Relocate the twin mce functions to arch/x86/mm/pat/set_memory.c
file where they belong.

While at it, fixup a function name in a comment.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
Changes since v9:
- fixup a 0day report: "no previous prototype for 'set_mce_nospec'",
  include linux/set_memory.h in set_memory.c.

 arch/x86/include/asm/set_memory.h |   52 -------------------------------------
 arch/x86/mm/pat/set_memory.c      |   51 +++++++++++++++++++++++++++++++++++-
 include/linux/set_memory.h        |    8 +++---
 3 files changed, 53 insertions(+), 58 deletions(-)

diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 78ca53512486..b45c4d27fd46 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -86,56 +86,4 @@ bool kernel_page_present(struct page *page);
 
 extern int kernel_set_to_readonly;
 
-#ifdef CONFIG_X86_64
-/*
- * Prevent speculative access to the page by either unmapping
- * it (if we do not require access to any part of the page) or
- * marking it uncacheable (if we want to try to retrieve data
- * from non-poisoned lines in the page).
- */
-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 (arch_is_platform_page(pfn << PAGE_SHIFT))
-		return 0;
-	/*
-	 * We would like to just call:
-	 *      set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1);
-	 * but doing that would radically increase the odds of a
-	 * speculative access to the poison page because we'd have
-	 * the virtual address of the kernel 1:1 mapping sitting
-	 * around in registers.
-	 * Instead we get tricky.  We create a non-canonical address
-	 * that looks just like the one we want, but has bit 63 flipped.
-	 * This relies on set_memory_XX() properly sanitizing any __pa()
-	 * results with __PHYSICAL_MASK or PTE_PFN_MASK.
-	 */
-	decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63));
-
-	if (unmap)
-		rc = set_memory_np(decoy_addr, 1);
-	else
-		rc = set_memory_uc(decoy_addr, 1);
-	if (rc)
-		pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn);
-	return rc;
-}
-#define set_mce_nospec set_mce_nospec
-
-/* Restore full speculative operation to the pfn. */
-static inline int clear_mce_nospec(unsigned long pfn)
-{
-	return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1);
-}
-#define clear_mce_nospec clear_mce_nospec
-#else
-/*
- * Few people would run a 32-bit kernel on a machine that supports
- * recoverable errors because they have too much memory to boot 32-bit.
- */
-#endif
-
 #endif /* _ASM_X86_SET_MEMORY_H */
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index abf5ed76e4b7..8297cf82c613 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -19,6 +19,7 @@
 #include <linux/vmstat.h>
 #include <linux/kernel.h>
 #include <linux/cc_platform.h>
+#include <linux/set_memory.h>
 
 #include <asm/e820/api.h>
 #include <asm/processor.h>
@@ -29,7 +30,6 @@
 #include <asm/pgalloc.h>
 #include <asm/proto.h>
 #include <asm/memtype.h>
-#include <asm/set_memory.h>
 #include <asm/hyperv-tlfs.h>
 #include <asm/mshyperv.h>
 
@@ -1816,7 +1816,7 @@ static inline int cpa_clear_pages_array(struct page **pages, int numpages,
 }
 
 /*
- * _set_memory_prot is an internal helper for callers that have been passed
+ * __set_memory_prot is an internal helper for callers that have been passed
  * a pgprot_t value from upper layers and a reservation has already been taken.
  * If you want to set the pgprot to a specific page protocol, use the
  * set_memory_xx() functions.
@@ -1925,6 +1925,53 @@ int set_memory_wb(unsigned long addr, int numpages)
 }
 EXPORT_SYMBOL(set_memory_wb);
 
+/*
+ * Prevent speculative access to the page by either unmapping
+ * it (if we do not require access to any part of the page) or
+ * marking it uncacheable (if we want to try to retrieve data
+ * from non-poisoned lines in the page).
+ */
+int set_mce_nospec(unsigned long pfn, bool unmap)
+{
+	unsigned long decoy_addr;
+	int rc;
+
+	if (!IS_ENABLED(CONFIG_64BIT))
+		return 0;
+
+	/* SGX pages are not in the 1:1 map */
+	if (arch_is_platform_page(pfn << PAGE_SHIFT))
+		return 0;
+	/*
+	 * We would like to just call:
+	 *      set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1);
+	 * but doing that would radically increase the odds of a
+	 * speculative access to the poison page because we'd have
+	 * the virtual address of the kernel 1:1 mapping sitting
+	 * around in registers.
+	 * Instead we get tricky.  We create a non-canonical address
+	 * that looks just like the one we want, but has bit 63 flipped.
+	 * This relies on set_memory_XX() properly sanitizing any __pa()
+	 * results with __PHYSICAL_MASK or PTE_PFN_MASK.
+	 */
+	decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63));
+
+	if (unmap)
+		rc = set_memory_np(decoy_addr, 1);
+	else
+		rc = set_memory_uc(decoy_addr, 1);
+	if (rc)
+		pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn);
+	return rc;
+}
+
+/* Restore full speculative operation to the pfn. */
+int clear_mce_nospec(unsigned long pfn)
+{
+	return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1);
+}
+EXPORT_SYMBOL_GPL(clear_mce_nospec);
+
 int set_memory_x(unsigned long addr, int numpages)
 {
 	if (!(__supported_pte_mask & _PAGE_NX))
diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
index f36be5166c19..683a6c3f7179 100644
--- a/include/linux/set_memory.h
+++ b/include/linux/set_memory.h
@@ -42,14 +42,14 @@ static inline bool can_set_direct_map(void)
 #endif
 #endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */
 
-#ifndef set_mce_nospec
+#ifdef CONFIG_X86_64
+int set_mce_nospec(unsigned long pfn, bool unmap);
+int clear_mce_nospec(unsigned long pfn);
+#else
 static inline int set_mce_nospec(unsigned long pfn, bool unmap)
 {
 	return 0;
 }
-#endif
-
-#ifndef clear_mce_nospec
 static inline int clear_mce_nospec(unsigned long pfn)
 {
 	return 0;