[PATCH 2/6] powerpc: Add enable_ppr kernel parameter to enable PPR save/restore
Haren Myneni
haren at linux.vnet.ibm.com
Sun Sep 9 21:37:51 EST 2012
enable_ppr kernel parameter is used to enable PPR save and restore.
Supported on Power7 and later processors.
By default, CPU_FTR_HAS_PPR is set for POWER7. If this parameter is not
passed, disable CPU_FTR_HAS_PPR.
Signed-off-by: Haren Myneni <haren at us.ibm.com>
---
Documentation/kernel-parameters.txt | 4 ++++
arch/powerpc/include/asm/cputable.h | 6 ++++--
arch/powerpc/kernel/setup_64.c | 14 ++++++++++++++
3 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ad7e2e5..2881e5f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -809,6 +809,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
to discrete, to make X server driver able to add WB
entry later. This parameter enables that.
+ enable_ppr [PPC/PSERIES]
+ Saves user defined PPR when process enters to kernel
+ and restores PPR at exit. But it impacts performance.
+
enable_timer_pin_1 [X86]
Enable PIN 1 of APIC timer
Can be useful to work around chipset bugs
diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index b3c083d..880c469 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -203,6 +203,7 @@ extern const char *powerpc_base_platform;
#define CPU_FTR_POPCNTD LONG_ASM_CONST(0x0800000000000000)
#define CPU_FTR_ICSWX LONG_ASM_CONST(0x1000000000000000)
#define CPU_FTR_VMX_COPY LONG_ASM_CONST(0x2000000000000000)
+#define CPU_FTR_HAS_PPR LONG_ASM_CONST(0x4000000000000000)
#ifndef __ASSEMBLY__
@@ -432,7 +433,8 @@ extern const char *powerpc_base_platform;
CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
CPU_FTR_DSCR | CPU_FTR_SAO | CPU_FTR_ASYM_SMT | \
CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
- CPU_FTR_ICSWX | CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY)
+ CPU_FTR_ICSWX | CPU_FTR_CFAR | CPU_FTR_HVMODE | \
+ CPU_FTR_VMX_COPY | CPU_FTR_HAS_PPR)
#define CPU_FTRS_CELL (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \
@@ -454,7 +456,7 @@ extern const char *powerpc_base_platform;
(CPU_FTRS_POWER3 | CPU_FTRS_RS64 | CPU_FTRS_POWER4 | \
CPU_FTRS_PPC970 | CPU_FTRS_POWER5 | CPU_FTRS_POWER6 | \
CPU_FTRS_POWER7 | CPU_FTRS_CELL | CPU_FTRS_PA6T | \
- CPU_FTR_VSX)
+ CPU_FTR_VSX | CPU_FTR_HAS_PPR)
#endif
#else
enum {
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 389bd4f..e4c1945 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -98,6 +98,8 @@ int dcache_bsize;
int icache_bsize;
int ucache_bsize;
+static u32 enable_ppr = 0;
+
#ifdef CONFIG_SMP
static char *smt_enabled_cmdline;
@@ -357,6 +359,9 @@ void __init setup_system(void)
{
DBG(" -> setup_system()\n");
+ if (cpu_has_feature(CPU_FTR_HAS_PPR) && !enable_ppr)
+ cur_cpu_spec->cpu_features &= ~CPU_FTR_HAS_PPR;
+
/* Apply the CPUs-specific and firmware specific fixups to kernel
* text (nop out sections not relevant to this CPU or this firmware)
*/
@@ -683,6 +688,15 @@ void __init setup_per_cpu_areas(void)
}
#endif
+/* early_ppr kernel parameter to save/restore PPR register */
+static int __init early_ppr_enabled(char *str)
+{
+ enable_ppr = 1;
+
+ return 0;
+}
+
+early_param("enable_ppr", early_ppr_enabled);
#ifdef CONFIG_PPC_INDIRECT_IO
struct ppc_pci_io ppc_pci_io;
--
1.7.10.4
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