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Message-Id: <1431714237-880-4-git-send-email-toshi.kani@hp.com>
Date: Fri, 15 May 2015 12:23:54 -0600
From: Toshi Kani <toshi.kani@...com>
To: bp@...en8.de, akpm@...ux-foundation.org, hpa@...or.com,
tglx@...utronix.de, mingo@...hat.com
Cc: linux-mm@...ck.org, x86@...nel.org, linux-kernel@...r.kernel.org,
dave.hansen@...el.com, Elliott@...com, pebolle@...cali.nl,
mcgrof@...e.com, Toshi Kani <toshi.kani@...com>
Subject: [PATCH v5 3/6] mtrr, x86: Fix MTRR state checks in mtrr_type_lookup()
'mtrr_state.enabled' contains the FE (fixed MTRRs enabled)
and E (MTRRs enabled) flags in MSR_MTRRdefType. Intel SDM,
section 11.11.2.1, defines these flags as follows:
- All MTRRs are disabled when the E flag is clear.
The FE flag has no affect when the E flag is clear.
- The default type is enabled when the E flag is set.
- MTRR variable ranges are enabled when the E flag is set.
- MTRR fixed ranges are enabled when both E and FE flags
are set.
MTRR state checks in __mtrr_type_lookup() do not match with
SDM. Hence, this patch makes the following changes:
- The current code detects MTRRs disabled when both E and
FE flags are clear in mtrr_state.enabled. Fix to detect
MTRRs disabled when the E flag is clear.
- The current code does not check if the FE bit is set in
mtrr_state.enabled when looking into the fixed entries.
Fix to check the FE flag.
- The current code returns the default type when the E flag
is clear in mtrr_state.enabled. However, the default type
is also disabled when the E flag is clear. Fix to remove
the code as this case is handled as MTRR disabled with
the 1st change.
In addition, this patch defines the E and FE flags in
mtrr_state.enabled as follows.
- FE flag: MTRR_STATE_MTRR_FIXED_ENABLED
- E flag: MTRR_STATE_MTRR_ENABLED
print_mtrr_state() and x86_get_mtrr_mem_range() are also updated
accordingly.
Signed-off-by: Toshi Kani <toshi.kani@...com>
---
arch/x86/include/asm/mtrr.h | 4 ++++
arch/x86/kernel/cpu/mtrr/cleanup.c | 3 ++-
arch/x86/kernel/cpu/mtrr/generic.c | 15 ++++++++-------
3 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h
index f768f62..ef92794 100644
--- a/arch/x86/include/asm/mtrr.h
+++ b/arch/x86/include/asm/mtrr.h
@@ -127,4 +127,8 @@ struct mtrr_gentry32 {
_IOW(MTRR_IOCTL_BASE, 9, struct mtrr_sentry32)
#endif /* CONFIG_COMPAT */
+/* Bit fields for enabled in struct mtrr_state_type */
+#define MTRR_STATE_MTRR_FIXED_ENABLED 0x01
+#define MTRR_STATE_MTRR_ENABLED 0x02
+
#endif /* _ASM_X86_MTRR_H */
diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c
index 5f90b85..70d7c93 100644
--- a/arch/x86/kernel/cpu/mtrr/cleanup.c
+++ b/arch/x86/kernel/cpu/mtrr/cleanup.c
@@ -98,7 +98,8 @@ x86_get_mtrr_mem_range(struct range *range, int nr_range,
continue;
base = range_state[i].base_pfn;
if (base < (1<<(20-PAGE_SHIFT)) && mtrr_state.have_fixed &&
- (mtrr_state.enabled & 1)) {
+ (mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED) &&
+ (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) {
/* Var MTRR contains UC entry below 1M? Skip it: */
printk(BIOS_BUG_MSG, i);
if (base + size <= (1<<(20-PAGE_SHIFT)))
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index e202d26..b0599db 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -119,14 +119,16 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat)
if (!mtrr_state_set)
return 0xFF;
- if (!mtrr_state.enabled)
+ if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED))
return 0xFF;
/* Make end inclusive end, instead of exclusive */
end--;
/* Look in fixed ranges. Just return the type as per start */
- if (mtrr_state.have_fixed && (start < 0x100000)) {
+ if ((start < 0x100000) &&
+ (mtrr_state.have_fixed) &&
+ (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) {
int idx;
if (start < 0x80000) {
@@ -149,9 +151,6 @@ 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
*/
- if (!(mtrr_state.enabled & 2))
- return mtrr_state.def_type;
-
prev_match = 0xFF;
for (i = 0; i < num_var_ranges; ++i) {
unsigned short start_state, end_state, inclusive;
@@ -355,7 +354,9 @@ static void __init print_mtrr_state(void)
mtrr_attrib_to_str(mtrr_state.def_type));
if (mtrr_state.have_fixed) {
pr_debug("MTRR fixed ranges %sabled:\n",
- mtrr_state.enabled & 1 ? "en" : "dis");
+ ((mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED) &&
+ (mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) ?
+ "en" : "dis");
print_fixed(0x00000, 0x10000, mtrr_state.fixed_ranges + 0);
for (i = 0; i < 2; ++i)
print_fixed(0x80000 + i * 0x20000, 0x04000,
@@ -368,7 +369,7 @@ static void __init print_mtrr_state(void)
print_fixed_last();
}
pr_debug("MTRR variable ranges %sabled:\n",
- mtrr_state.enabled & 2 ? "en" : "dis");
+ mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED ? "en" : "dis");
high_width = (__ffs64(size_or_mask) - (32 - PAGE_SHIFT) + 3) / 4;
for (i = 0; i < num_var_ranges; ++i) {
--
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