[POWERPC] Implement SLB shadow buffer
This adds a shadow buffer for the SLBs and regsiters it with PHYP.
Only the bolted SLB entries (top 3) are shadowed.
The SLB shadow buffer tells the hypervisor what the kernel needs to
have in the SLB for the kernel to be able to function. The hypervisor
can use this information to speed up partition context switches.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index ac06319..2ef7ea8 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -135,11 +135,13 @@
DEFINE(PACA_STARTPURR, offsetof(struct paca_struct, startpurr));
DEFINE(PACA_USER_TIME, offsetof(struct paca_struct, user_time));
DEFINE(PACA_SYSTEM_TIME, offsetof(struct paca_struct, system_time));
+ DEFINE(PACA_SLBSHADOWPTR, offsetof(struct paca_struct, slb_shadow_ptr));
DEFINE(LPPACASRR0, offsetof(struct lppaca, saved_srr0));
DEFINE(LPPACASRR1, offsetof(struct lppaca, saved_srr1));
DEFINE(LPPACAANYINT, offsetof(struct lppaca, int_dword.any_int));
DEFINE(LPPACADECRINT, offsetof(struct lppaca, int_dword.fields.decr_int));
+ DEFINE(SLBSHADOW_SAVEAREA, offsetof(struct slb_shadow, save_area));
#endif /* CONFIG_PPC64 */
/* RTAS */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 54d9f5c..5baea49 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -323,6 +323,11 @@
* The code which creates the new task context is in 'copy_thread'
* in arch/powerpc/kernel/process.c
*/
+#define SHADOW_SLB_BOLTED_STACK_ESID \
+ (SLBSHADOW_SAVEAREA + 0x10*(SLB_NUM_BOLTED-1))
+#define SHADOW_SLB_BOLTED_STACK_VSID \
+ (SLBSHADOW_SAVEAREA + 0x10*(SLB_NUM_BOLTED-1) + 8)
+
.align 7
_GLOBAL(_switch)
mflr r0
@@ -375,6 +380,14 @@
ld r7,KSP_VSID(r4) /* Get new stack's VSID */
oris r0,r6,(SLB_ESID_V)@h
ori r0,r0,(SLB_NUM_BOLTED-1)@l
+
+ /* Update the last bolted SLB */
+ ld r9,PACA_SLBSHADOWPTR(r13)
+ li r12,0
+ std r12,SHADOW_SLB_BOLTED_STACK_ESID(r9) /* Clear ESID */
+ std r7,SHADOW_SLB_BOLTED_STACK_VSID(r9) /* Save VSID */
+ std r0,SHADOW_SLB_BOLTED_STACK_ESID(r9) /* Save ESID */
+
slbie r6
slbie r6 /* Workaround POWER5 < DD2.1 issue */
slbmte r7,r0
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
index c68741f..55f1a25 100644
--- a/arch/powerpc/kernel/paca.c
+++ b/arch/powerpc/kernel/paca.c
@@ -17,6 +17,7 @@
#include <asm/lppaca.h>
#include <asm/iseries/it_lp_reg_save.h>
#include <asm/paca.h>
+#include <asm/mmu.h>
/* This symbol is provided by the linker - let it fill in the paca
@@ -45,6 +46,17 @@
},
};
+/*
+ * 3 persistent SLBs are registered here. The buffer will be zero
+ * initially, hence will all be invaild until we actually write them.
+ */
+struct slb_shadow slb_shadow[] __cacheline_aligned = {
+ [0 ... (NR_CPUS-1)] = {
+ .persistent = SLB_NUM_BOLTED,
+ .buffer_length = sizeof(struct slb_shadow),
+ },
+};
+
/* The Paca is an array with one entry per processor. Each contains an
* lppaca, which contains the information shared between the
* hypervisor and Linux.
@@ -59,7 +71,8 @@
.lock_token = 0x8000, \
.paca_index = (number), /* Paca Index */ \
.kernel_toc = (unsigned long)(&__toc_start) + 0x8000UL, \
- .hw_cpu_id = 0xffff,
+ .hw_cpu_id = 0xffff, \
+ .slb_shadow_ptr = &slb_shadow[number],
#ifdef CONFIG_PPC_ISERIES
#define PACA_INIT_ISERIES(number) \
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index de0c884..d373391 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -22,6 +22,8 @@
#include <asm/paca.h>
#include <asm/cputable.h>
#include <asm/cacheflush.h>
+#include <asm/smp.h>
+#include <linux/compiler.h>
#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
@@ -50,9 +52,32 @@
return (get_kernel_vsid(ea) << SLB_VSID_SHIFT) | flags;
}
-static inline void create_slbe(unsigned long ea, unsigned long flags,
- unsigned long entry)
+static inline void slb_shadow_update(unsigned long esid, unsigned long vsid,
+ unsigned long entry)
{
+ /*
+ * Clear the ESID first so the entry is not valid while we are
+ * updating it.
+ */
+ get_slb_shadow()->save_area[entry].esid = 0;
+ barrier();
+ get_slb_shadow()->save_area[entry].vsid = vsid;
+ barrier();
+ get_slb_shadow()->save_area[entry].esid = esid;
+
+}
+
+static inline void create_shadowed_slbe(unsigned long ea, unsigned long flags,
+ unsigned long entry)
+{
+ /*
+ * Updating the shadow buffer before writing the SLB ensures
+ * we don't get a stale entry here if we get preempted by PHYP
+ * between these two statements.
+ */
+ slb_shadow_update(mk_esid_data(ea, entry), mk_vsid_data(ea, flags),
+ entry);
+
asm volatile("slbmte %0,%1" :
: "r" (mk_vsid_data(ea, flags)),
"r" (mk_esid_data(ea, entry))
@@ -77,6 +102,10 @@
if ((ksp_esid_data & ESID_MASK) == PAGE_OFFSET)
ksp_esid_data &= ~SLB_ESID_V;
+ /* Only third entry (stack) may change here so only resave that */
+ slb_shadow_update(ksp_esid_data,
+ mk_vsid_data(ksp_esid_data, lflags), 2);
+
/* We need to do this all in asm, so we're sure we don't touch
* the stack between the slbia and rebolting it. */
asm volatile("isync\n"
@@ -209,9 +238,9 @@
asm volatile("isync":::"memory");
asm volatile("slbmte %0,%0"::"r" (0) : "memory");
asm volatile("isync; slbia; isync":::"memory");
- create_slbe(PAGE_OFFSET, lflags, 0);
+ create_shadowed_slbe(PAGE_OFFSET, lflags, 0);
- create_slbe(VMALLOC_START, vflags, 1);
+ create_shadowed_slbe(VMALLOC_START, vflags, 1);
/* We don't bolt the stack for the time being - we're in boot,
* so the stack is in the bolted segment. By the time it goes
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 6cbf142..1820a0b 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -252,18 +252,34 @@
void vpa_init(int cpu)
{
int hwcpu = get_hard_smp_processor_id(cpu);
- unsigned long vpa = __pa(&lppaca[cpu]);
+ unsigned long addr;
long ret;
if (cpu_has_feature(CPU_FTR_ALTIVEC))
lppaca[cpu].vmxregs_in_use = 1;
- ret = register_vpa(hwcpu, vpa);
+ addr = __pa(&lppaca[cpu]);
+ ret = register_vpa(hwcpu, addr);
- if (ret)
+ if (ret) {
printk(KERN_ERR "WARNING: vpa_init: VPA registration for "
"cpu %d (hw %d) of area %lx returns %ld\n",
- cpu, hwcpu, vpa, ret);
+ cpu, hwcpu, addr, ret);
+ return;
+ }
+ /*
+ * PAPR says this feature is SLB-Buffer but firmware never
+ * reports that. All SPLPAR support SLB shadow buffer.
+ */
+ addr = __pa(&slb_shadow[cpu]);
+ if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
+ ret = register_slb_shadow(hwcpu, addr);
+ if (ret)
+ printk(KERN_ERR
+ "WARNING: vpa_init: SLB shadow buffer "
+ "registration for cpu %d (hw %d) of area %lx "
+ "returns %ld\n", cpu, hwcpu, addr, ret);
+ }
}
long pSeries_lpar_hpte_insert(unsigned long hpte_group,
diff --git a/arch/powerpc/platforms/pseries/plpar_wrappers.h b/arch/powerpc/platforms/pseries/plpar_wrappers.h
index ebd15de..3eb7b29 100644
--- a/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ b/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -37,6 +37,16 @@
return vpa_call(0x1, cpu, vpa);
}
+static inline long unregister_slb_shadow(unsigned long cpu, unsigned long vpa)
+{
+ return vpa_call(0x7, cpu, vpa);
+}
+
+static inline long register_slb_shadow(unsigned long cpu, unsigned long vpa)
+{
+ return vpa_call(0x3, cpu, vpa);
+}
+
extern void vpa_init(int cpu);
static inline long plpar_pte_enter(unsigned long flags,
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index de214d8..6ebeecf 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -234,9 +234,17 @@
{
/* Don't risk a hypervisor call if we're crashing */
if (firmware_has_feature(FW_FEATURE_SPLPAR) && !crash_shutdown) {
- unsigned long vpa = __pa(get_lppaca());
+ unsigned long addr;
- if (unregister_vpa(hard_smp_processor_id(), vpa)) {
+ addr = __pa(get_slb_shadow());
+ if (unregister_slb_shadow(hard_smp_processor_id(), addr))
+ printk("SLB shadow buffer deregistration of "
+ "cpu %u (hw_cpu_id %d) failed\n",
+ smp_processor_id(),
+ hard_smp_processor_id());
+
+ addr = __pa(get_lppaca());
+ if (unregister_vpa(hard_smp_processor_id(), addr)) {
printk("VPA deregistration of cpu %u (hw_cpu_id %d) "
"failed\n", smp_processor_id(),
hard_smp_processor_id());