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x86/mce: relocate set{clear}_mce_nospec() functions
Relocate the twin mce functions to arch/x86/mm/pat/set_memory.c
file where they belong.

Signed-off-by: Jane Chu <jane.chu@oracle.com>
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jchu314atgithub authored and intel-lab-lkp committed Mar 19, 2022
1 parent 9ff6c99 commit 71b9b09
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Showing 3 changed files with 53 additions and 56 deletions.
52 changes: 0 additions & 52 deletions arch/x86/include/asm/set_memory.h
Expand Up @@ -88,56 +88,4 @@ void notify_range_enc_status_changed(unsigned long vaddr, int npages, bool enc);

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 */
48 changes: 48 additions & 0 deletions arch/x86/mm/pat/set_memory.c
Expand Up @@ -1925,6 +1925,54 @@ int set_memory_wb(unsigned long addr, int numpages)
}
EXPORT_SYMBOL(set_memory_wb);

#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).
*/
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;
}
EXPORT_SYMBOL(set_mce_nospec);

/* 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(clear_mce_nospec);

#endif

int set_memory_x(unsigned long addr, int numpages)
{
if (!(__supported_pte_mask & _PAGE_NX))
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9 changes: 5 additions & 4 deletions include/linux/set_memory.h
Expand Up @@ -42,20 +42,21 @@ 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;
}
#endif


#ifndef CONFIG_ARCH_HAS_MEM_ENCRYPT
static inline int set_memory_encrypted(unsigned long addr, int numpages)
{
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