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x86/mm/mtrr: Use symbolic define as a retval for disabled MTRRs

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mtrr_type_lookup() returns verbatim 0xFF when MTRRs are
disabled. This patch defines MTRR_TYPE_INVALID to clarify the
meaning of this value, and documents its usage.

Document the return values of the kernel virtual address mapping
helpers pud_set_huge(), pmd_set_huge, pud_clear_huge() and
pmd_clear_huge().

There is no functional change in this patch.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Elliott@hp.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@intel.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: pebolle@tiscali.nl
Link: http://lkml.kernel.org/r/1431714237-880-5-git-send-email-toshi.kani@hp.com
Link: http://lkml.kernel.org/r/1432628901-18044-5-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Toshi Kani 2015-05-26 10:28:07 +02:00 committed by Ingo Molnar
parent 9b3aca6208
commit 3d3ca416d9
4 changed files with 47 additions and 19 deletions
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2
arch/x86/include/asm/mtrr.h
View File

@ -55,7 +55,7 @@ static inline u8 mtrr_type_lookup(u64 addr, u64 end)
/*
* Return no-MTRRs:
*/
return 0xff;
return MTRR_TYPE_INVALID;
}
#define mtrr_save_fixed_ranges(arg) do {} while (0)
#define mtrr_save_state() do {} while (0)

8
arch/x86/include/uapi/asm/mtrr.h
View File

@ -103,7 +103,7 @@ struct mtrr_state_type {
#define MTRRIOC_GET_PAGE_ENTRY _IOWR(MTRR_IOCTL_BASE, 8, struct mtrr_gentry)
#define MTRRIOC_KILL_PAGE_ENTRY _IOW(MTRR_IOCTL_BASE, 9, struct mtrr_sentry)
/* These are the region types */
/* MTRR memory types, which are defined in SDM */
#define MTRR_TYPE_UNCACHABLE 0
#define MTRR_TYPE_WRCOMB 1
/*#define MTRR_TYPE_ 2*/
@ -113,5 +113,11 @@ struct mtrr_state_type {
#define MTRR_TYPE_WRBACK 6
#define MTRR_NUM_TYPES 7
/*
* Invalid MTRR memory type. mtrr_type_lookup() returns this value when
* MTRRs are disabled. Note, this value is allocated from the reserved
* values (0x7-0xff) of the MTRR memory types.
*/
#define MTRR_TYPE_INVALID 0xff
#endif /* _UAPI_ASM_X86_MTRR_H */

14
arch/x86/kernel/cpu/mtrr/generic.c
View File

@ -104,7 +104,7 @@ static int check_type_overlap(u8 *prev, u8 *curr)
/*
* Error/Semi-error returns:
* 0xFF - when MTRR is not enabled
* MTRR_TYPE_INVALID - when MTRR is not enabled
* *repeat == 1 implies [start:end] spanned across MTRR range and type returned
* corresponds only to [start:*partial_end].
* Caller has to lookup again for [*partial_end:end].
@ -117,10 +117,10 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
*repeat = 0;
if (!mtrr_state_set)
return 0xFF;
return MTRR_TYPE_INVALID;
if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED))
return 0xFF;
return MTRR_TYPE_INVALID;
/* Make end inclusive end, instead of exclusive */
end--;
@ -151,7 +151,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
* Look of multiple ranges matching this address and pick type
* as per MTRR precedence
*/
prev_match = 0xFF;
prev_match = MTRR_TYPE_INVALID;
for (i = 0; i < num_var_ranges; ++i) {
unsigned short start_state, end_state, inclusive;
@ -206,7 +206,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
continue;
curr_match = mtrr_state.var_ranges[i].base_lo & 0xff;
if (prev_match == 0xFF) {
if (prev_match == MTRR_TYPE_INVALID) {
prev_match = curr_match;
continue;
}
@ -220,7 +220,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
return MTRR_TYPE_WRBACK;
}
if (prev_match != 0xFF)
if (prev_match != MTRR_TYPE_INVALID)
return prev_match;
return mtrr_state.def_type;
@ -229,7 +229,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
/*
* Returns the effective MTRR type for the region
* Error return:
* 0xFF - when MTRR is not enabled
* MTRR_TYPE_INVALID - when MTRR is not enabled
*/
u8 mtrr_type_lookup(u64 start, u64 end)
{

42
arch/x86/mm/pgtable.c
View File

@ -563,16 +563,22 @@ void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys,
}
#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
/**
* pud_set_huge - setup kernel PUD mapping
*
* MTRR can override PAT memory types with 4KiB granularity. Therefore,
* this function does not set up a huge page when the range is covered
* by a non-WB type of MTRR. MTRR_TYPE_INVALID indicates that MTRR are
* disabled.
*
* Returns 1 on success and 0 on failure.
*/
int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
{
u8 mtrr;
/*
* Do not use a huge page when the range is covered by non-WB type
* of MTRRs.
*/
mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE);
if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF))
if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != MTRR_TYPE_INVALID))
return 0;
prot = pgprot_4k_2_large(prot);
@ -584,16 +590,22 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
return 1;
}
/**
* pmd_set_huge - setup kernel PMD mapping
*
* MTRR can override PAT memory types with 4KiB granularity. Therefore,
* this function does not set up a huge page when the range is covered
* by a non-WB type of MTRR. MTRR_TYPE_INVALID indicates that MTRR are
* disabled.
*
* Returns 1 on success and 0 on failure.
*/
int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
{
u8 mtrr;
/*
* Do not use a huge page when the range is covered by non-WB type
* of MTRRs.
*/
mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE);
if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF))
if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != MTRR_TYPE_INVALID))
return 0;
prot = pgprot_4k_2_large(prot);
@ -605,6 +617,11 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
return 1;
}
/**
* pud_clear_huge - clear kernel PUD mapping when it is set
*
* Returns 1 on success and 0 on failure (no PUD map is found).
*/
int pud_clear_huge(pud_t *pud)
{
if (pud_large(*pud)) {
@ -615,6 +632,11 @@ int pud_clear_huge(pud_t *pud)
return 0;
}
/**
* pmd_clear_huge - clear kernel PMD mapping when it is set
*
* Returns 1 on success and 0 on failure (no PMD map is found).
*/
int pmd_clear_huge(pmd_t *pmd)
{
if (pmd_large(*pmd)) {