spufs: switchable spu contexts

diff -urN linux-2.6.13-rc6.fix/arch/ppc64/kernel/spu_base.c linux-2.6.13-rc6/arch/ppc64/kernel/spu_base.c
@@ -62,7 +62,9 @@
 static void spu_restart_dma(struct spu *spu)
 {
 	struct spu_priv2 __iomem *priv2 = spu->priv2;
-	out_be64(&priv2->mfc_control_RW, MFC_CNTL_RESTART_DMA_COMMAND);
+
+	if (!test_bit(SPU_CONTEXT_SWITCH_PENDING_nr, &spu->flags))
+		out_be64(&priv2->mfc_control_RW, MFC_CNTL_RESTART_DMA_COMMAND);
 }
 
 static int __spu_trap_data_seg(struct spu *spu, unsigned long ea)

@@ -72,6 +74,11 @@
 
 	pr_debug("%s\n", __FUNCTION__);
 
+	if (test_bit(SPU_CONTEXT_SWITCH_ACTIVE_nr, &spu->flags)) {
+		printk("%s: invalid access during switch!\n", __func__);
+		return 1;
+	}
+
 	if (REGION_ID(ea) != USER_REGION_ID) {
 		pr_debug("invalid region access at %016lx\n", ea);
 		return 1;

@@ -98,6 +105,7 @@
 	return 0;
 }	
 
+extern int hash_page(unsigned long ea, unsigned long access, unsigned long trap); //XXX
 static int __spu_trap_data_map(struct spu *spu, unsigned long ea)
 {
 	unsigned long dsisr;

@@ -107,8 +115,21 @@
 	priv1 = spu->priv1;
 	dsisr = in_be64(&priv1->mfc_dsisr_RW);
 
-	wake_up(&spu->stop_wq);
+	/* Handle kernel space hash faults immediately.
+	   User hash faults need to be deferred to process context. */
+	if ((dsisr & MFC_DSISR_PTE_NOT_FOUND)
+	    && REGION_ID(ea) != USER_REGION_ID
+	    && hash_page(ea, _PAGE_PRESENT, 0x300) == 0) {
+		spu_restart_dma(spu);
+		return 0;
+	}
+
+	if (test_bit(SPU_CONTEXT_SWITCH_ACTIVE_nr, &spu->flags)) {
+		printk("%s: invalid access during switch!\n", __func__);
+		return 1;
+	}
 
+	wake_up(&spu->stop_wq);
 	return 0;
 }
 

@@ -378,7 +399,6 @@
 }
 EXPORT_SYMBOL(spu_free);
 
-extern int hash_page(unsigned long ea, unsigned long access, unsigned long trap); //XXX
 static int spu_handle_mm_fault(struct spu *spu)
 {
 	struct spu_priv1 __iomem *priv1;

@@ -646,6 +666,7 @@
 	spu->slb_replace = 0;
 	spu->mm = NULL;
 	spu->class_0_pending = 0;
+	spu->flags = 0UL;
 	spin_lock_init(&spu->register_lock);
 
 	out_be64(&spu->priv1->mfc_sdr_RW, mfspr(SPRN_SDR1));

diff -urN linux-2.6.13-rc6.fix/fs/spufs/context.c linux-2.6.13-rc6/fs/spufs/context.c
@@ -22,6 +22,7 @@
 
 #include <linux/slab.h>
 #include <asm/spu.h>
+#include <asm/spu_csa.h>
 #include "spufs.h"
 
 struct spu_context *alloc_spu_context(void)

@@ -30,9 +31,25 @@
 	ctx = kmalloc(sizeof *ctx, GFP_KERNEL);
 	if (!ctx)
 		goto out;
+	/* Future enhancement: do not call spu_alloc()
+	 * here.  This step should be deferred until
+	 * spu_run()!!
+	 *
+	 * More work needs to be done to read(),
+	 * write(), mmap(), etc., so that operations
+	 * are performed on CSA when the context is
+	 * not currently being run.  In this way we
+	 * can support arbitrarily large number of
+	 * entries in /spu, allow state queries, etc.
+	 */
 	ctx->spu = spu_alloc();
 	if (!ctx->spu)
 		goto out_free;
+	spu_init_csa(&ctx->csa);
+	if (!ctx->csa.lscsa) {
+		spu_free(ctx->spu);
+		goto out_free;
+	}
 	init_rwsem(&ctx->backing_sema);
 	spin_lock_init(&ctx->mmio_lock);
 	kref_init(&ctx->kref);

@@ -50,6 +67,7 @@
 	ctx = container_of(kref, struct spu_context, kref);
 	if (ctx->spu)
 		spu_free(ctx->spu);
+	spu_fini_csa(&ctx->csa);
 	kfree(ctx);
 }
 

diff -urN linux-2.6.13-rc6.fix/fs/spufs/spufs.h linux-2.6.13-rc6/fs/spufs/spufs.h
@@ -28,6 +28,7 @@
 #include <linux/fs.h>
 
 #include <asm/spu.h>
+#include <asm/spu_csa.h>
 
 /* The magic number for our file system */
 enum {

@@ -36,6 +37,7 @@
 
 struct spu_context {
 	struct spu *spu;		  /* pointer to a physical SPU */
+	struct spu_state csa;		  /* SPU context save area. */
 	struct rw_semaphore backing_sema; /* protects the above */
 	spinlock_t mmio_lock;		  /* protects mmio access */
 

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