[IA64] Multiple outstanding ptc.g instruction support

According to SDM2.2, Itanium supports multiple outstanding ptc.g instructions.
But current kernel function ia64_global_tlb_purge() uses a spinlock to serialize
ptc.g instructions issued by multiple processors. This serialization might have
scalability issue on a big SMP machine where many processors could purge TLB
in parallel.

The patch fixes this problem by issuing multiple ptc.g instructions in
ia64_global_tlb_purge(). It also adds support for the "PALO" table to get
a platform view of the max number of outstanding ptc.g instructions (which
may be different from the processor view found from PAL_VM_SUMMARY).

PALO specification can be found at: http://www.dig64.org/home/DIG64_PALO_R1_0.pdf

spinaphore implementation by Matthew Wilcox.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

2 files changed, 50 insertions, 2 deletions

diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index 728d7247a1a..003cd09b073 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -37,6 +37,7 @@
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/mca.h>
+#include <asm/tlbflush.h>
 
 #define EFI_DEBUG	0
 
@@ -403,6 +404,41 @@ efi_get_pal_addr (void)
 	return NULL;
 }
 
+
+static u8 __init palo_checksum(u8 *buffer, u32 length)
+{
+	u8 sum = 0;
+	u8 *end = buffer + length;
+
+	while (buffer < end)
+		sum = (u8) (sum + *(buffer++));
+
+	return sum;
+}
+
+/*
+ * Parse and handle PALO table which is published at:
+ * http://www.dig64.org/home/DIG64_PALO_R1_0.pdf
+ */
+static void __init handle_palo(unsigned long palo_phys)
+{
+	struct palo_table *palo = __va(palo_phys);
+	u8  checksum;
+
+	if (strncmp(palo->signature, PALO_SIG, sizeof(PALO_SIG) - 1)) {
+		printk(KERN_INFO "PALO signature incorrect.\n");
+		return;
+	}
+
+	checksum = palo_checksum((u8 *)palo, palo->length);
+	if (checksum) {
+		printk(KERN_INFO "PALO checksum incorrect.\n");
+		return;
+	}
+
+	setup_ptcg_sem(palo->max_tlb_purges, 1);
+}
+
 void
 efi_map_pal_code (void)
 {
@@ -432,6 +468,7 @@ efi_init (void)
 	u64 efi_desc_size;
 	char *cp, vendor[100] = "unknown";
 	int i;
+	unsigned long palo_phys;
 
 	/*
 	 * It's too early to be able to use the standard kernel command line
@@ -496,6 +533,8 @@ efi_init (void)
 	efi.hcdp       = EFI_INVALID_TABLE_ADDR;
 	efi.uga        = EFI_INVALID_TABLE_ADDR;
 
+	palo_phys      = EFI_INVALID_TABLE_ADDR;
+
 	for (i = 0; i < (int) efi.systab->nr_tables; i++) {
 		if (efi_guidcmp(config_tables[i].guid, MPS_TABLE_GUID) == 0) {
 			efi.mps = config_tables[i].table;
@@ -515,10 +554,17 @@ efi_init (void)
 		} else if (efi_guidcmp(config_tables[i].guid, HCDP_TABLE_GUID) == 0) {
 			efi.hcdp = config_tables[i].table;
 			printk(" HCDP=0x%lx", config_tables[i].table);
+		} else if (efi_guidcmp(config_tables[i].guid,
+			 PROCESSOR_ABSTRACTION_LAYER_OVERWRITE_GUID) == 0) {
+			palo_phys = config_tables[i].table;
+			printk(" PALO=0x%lx", config_tables[i].table);
 		}
 	}
 	printk("\n");
 
+	if (palo_phys != EFI_INVALID_TABLE_ADDR)
+		handle_palo(palo_phys);
+
 	runtime = __va(efi.systab->runtime);
 	efi.get_time = phys_get_time;
 	efi.set_time = phys_set_time;
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 4aa9eaea76c..1cbd26340d8 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -59,6 +59,7 @@
 #include <asm/setup.h>
 #include <asm/smp.h>
 #include <asm/system.h>
+#include <asm/tlbflush.h>
 #include <asm/unistd.h>
 #include <asm/hpsim.h>
 
@@ -946,9 +947,10 @@ cpu_init (void)
 #endif
 
 	/* set ia64_ctx.max_rid to the maximum RID that is supported by all CPUs: */
-	if (ia64_pal_vm_summary(NULL, &vmi) == 0)
+	if (ia64_pal_vm_summary(NULL, &vmi) == 0) {
 		max_ctx = (1U << (vmi.pal_vm_info_2_s.rid_size - 3)) - 1;
-	else {
+		setup_ptcg_sem(vmi.pal_vm_info_2_s.max_purges, 0);
+	} else {
 		printk(KERN_WARNING "cpu_init: PAL VM summary failed, assuming 18 RID bits\n");
 		max_ctx = (1U << 15) - 1;	/* use architected minimum */
 	}