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Message-ID: <165272527328.90175.8336008202048685278.stgit@dwillia2-desk3.amr.corp.intel.com>
Date: Mon, 16 May 2022 11:21:46 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: linux-kernel@...r.kernel.org
Cc: Christoph Hellwig <hch@....de>, Jane Chu <jane.chu@...cle.com>,
Borislav Petkov <bp@...e.de>,
Stephen Rothwell <sfr@...b.auug.org.au>, x86@...nel.org,
nvdimm@...ts.linux.dev, linux-fsdevel@...r.kernel.org
Subject: [PATCH v11 2/7] x86/mce: relocate set{clear}_mce_nospec() functions
From: Jane Chu <jane.chu@...cle.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@....de>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Jane Chu <jane.chu@...cle.com>
Acked-by: Borislav Petkov <bp@...e.de>
Cc: Stephen Rothwell <sfr@...b.auug.org.au>
[sfr: gate {set,clear}_mce_nospec() by CONFIG_X86_64]
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
Changes since v10:
- Fix a compile error with 32-bit builds (Stephen)
arch/x86/include/asm/set_memory.h | 52 -------------------------------------
arch/x86/mm/pat/set_memory.c | 50 ++++++++++++++++++++++++++++++++++--
include/linux/set_memory.h | 8 +++---
3 files changed, 52 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..0caf4b0edcbc 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 +1925,52 @@ 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).
+ */
+#ifdef CONFIG_X86_64
+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;
+}
+
+/* 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);
+#endif /* CONFIG_X86_64 */
+
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;
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